API ¶

New in version 8.0: confirmation_prompt can be a custom string.

Changelog

New in version 7.0: Added the show_choices parameter.

New in version 6.0: Added unicode support for cmd.exe on Windows.

New in version 4.0: Added the err parameter.

click.confirm(text, default=False, abort=False, prompt_suffix=': ', show_default=True, err=False)¶

Prompts for confirmation (yes/no question).

If the user aborts the input by sending a interrupt signal this function will catch it and raise a Abort exception.

Parameters

text (str) – the question to ask.
default (Optional[bool]) – The default value to use when no input is given. If None, repeat until input is given.
abort (bool) – if this is set to True a negative answer aborts the exception by raising Abort.
prompt_suffix (str) – a suffix that should be added to the prompt.
show_default (bool) – shows or hides the default value in the prompt.
err (bool) – if set to true the file defaults to stderr instead of stdout, the same as with echo.

Return type

bool

Changed in version 8.0: Repeat until input is given if default is None.

Changelog

New in version 4.0: Added the err parameter.

click.progressbar(iterable=None, length=None, label=None, show_eta=True, show_percent=None, show_pos=False, item_show_func=None, fill_char='#', empty_char='-', bar_template='%(label)s [%(bar)s] %(info)s', info_sep=' ', width=36, file=None, color=None, update_min_steps=1)¶

This function creates an iterable context manager that can be used to iterate over something while showing a progress bar. It will either iterate over the iterable or length items (that are counted up). While iteration happens, this function will print a rendered progress bar to the given file (defaults to stdout) and will attempt to calculate remaining time and more. By default, this progress bar will not be rendered if the file is not a terminal.

The context manager creates the progress bar. When the context manager is entered the progress bar is already created. With every iteration over the progress bar, the iterable passed to the bar is advanced and the bar is updated. When the context manager exits, a newline is printed and the progress bar is finalized on screen.

Note: The progress bar is currently designed for use cases where the total progress can be expected to take at least several seconds. Because of this, the ProgressBar class object won’t display progress that is considered too fast, and progress where the time between steps is less than a second.

No printing must happen or the progress bar will be unintentionally destroyed.

Example usage:

with progressbar(items) as bar:
    for item in bar:
        do_something_with(item)

Alternatively, if no iterable is specified, one can manually update the progress bar through the update() method instead of directly iterating over the progress bar. The update method accepts the number of steps to increment the bar with:

with progressbar(length=chunks.total_bytes) as bar:
    for chunk in chunks:
        process_chunk(chunk)
        bar.update(chunks.bytes)

The update() method also takes an optional value specifying the current_item at the new position. This is useful when used together with item_show_func to customize the output for each manual step:

with click.progressbar(
    length=total_size,
    label='Unzipping archive',
    item_show_func=lambda a: a.filename
) as bar:
    for archive in zip_file:
        archive.extract()
        bar.update(archive.size, archive)

Parameters

iterable (Optional[Iterable[click.termui.V]]) – an iterable to iterate over. If not provided the length is required.
length (Optional[int]) – the number of items to iterate over. By default the progressbar will attempt to ask the iterator about its length, which might or might not work. If an iterable is also provided this parameter can be used to override the length. If an iterable is not provided the progress bar will iterate over a range of that length.
label (Optional[str]) – the label to show next to the progress bar.
show_eta (bool) – enables or disables the estimated time display. This is automatically disabled if the length cannot be determined.
show_percent (Optional[bool]) – enables or disables the percentage display. The default is True if the iterable has a length or False if not.
show_pos (bool) – enables or disables the absolute position display. The default is False.
item_show_func (Optional[Callable[[Optional[click.termui.V]], Optional[str]]]) – A function called with the current item which can return a string to show next to the progress bar. If the function returns None nothing is shown. The current item can be None, such as when entering and exiting the bar.
fill_char (str) – the character to use to show the filled part of the progress bar.
empty_char (str) – the character to use to show the non-filled part of the progress bar.
bar_template (str) – the format string to use as template for the bar. The parameters in it are label for the label, bar for the progress bar and info for the info section.
info_sep (str) – the separator between multiple info items (eta etc.)
width (int) – the width of the progress bar in characters, 0 means full terminal width
file (Optional[TextIO]) – The file to write to. If this is not a terminal then only the label is printed.
color (Optional[bool]) – controls if the terminal supports ANSI colors or not. The default is autodetection. This is only needed if ANSI codes are included anywhere in the progress bar output which is not the case by default.
update_min_steps (int) – Render only when this many updates have completed. This allows tuning for very fast iterators.

Return type

ProgressBar[V]

Changed in version 8.0: Output is shown even if execution time is less than 0.5 seconds.

Changed in version 8.0: item_show_func shows the current item, not the previous one.

Changed in version 8.0: Labels are echoed if the output is not a TTY. Reverts a change in 7.0 that removed all output.

New in version 8.0: Added the update_min_steps parameter.

Changelog

Changed in version 4.0: Added the color parameter. Added the update method to the object.

New in version 2.0.

click.clear()¶

Clears the terminal screen. This will have the effect of clearing the whole visible space of the terminal and moving the cursor to the top left. This does not do anything if not connected to a terminal.

Changelog

New in version 2.0.

Return type: None

click.style(text, fg=None, bg=None, bold=None, dim=None, underline=None, overline=None, italic=None, blink=None, reverse=None, strikethrough=None, reset=True)¶

Styles a text with ANSI styles and returns the new string. By default the styling is self contained which means that at the end of the string a reset code is issued. This can be prevented by passing reset=False.

Examples:

click.echo(click.style('Hello World!', fg='green'))
click.echo(click.style('ATTENTION!', blink=True))
click.echo(click.style('Some things', reverse=True, fg='cyan'))
click.echo(click.style('More colors', fg=(255, 12, 128), bg=117))

Supported color names:

black (might be a gray)
red
green
yellow (might be an orange)
blue
magenta
cyan
white (might be light gray)
bright_black
bright_red
bright_green
bright_yellow
bright_blue
bright_magenta
bright_cyan
bright_white
reset (reset the color code only)

If the terminal supports it, color may also be specified as:

An integer in the interval [0, 255]. The terminal must support 8-bit/256-color mode.
An RGB tuple of three integers in [0, 255]. The terminal must support 24-bit/true-color mode.

See https://en.wikipedia.org/wiki/ANSI_color and https://gist.github.com/XVilka/8346728 for more information.

Parameters

text (Any) – the string to style with ansi codes.
fg (Optional[Union[int, Tuple[int, int, int], str]]) – if provided this will become the foreground color.
bg (Optional[Union[int, Tuple[int, int, int], str]]) – if provided this will become the background color.
bold (Optional[bool]) – if provided this will enable or disable bold mode.
dim (Optional[bool]) – if provided this will enable or disable dim mode. This is badly supported.
underline (Optional[bool]) – if provided this will enable or disable underline.
overline (Optional[bool]) – if provided this will enable or disable overline.
italic (Optional[bool]) – if provided this will enable or disable italic.
blink (Optional[bool]) – if provided this will enable or disable blinking.
reverse (Optional[bool]) – if provided this will enable or disable inverse rendering (foreground becomes background and the other way round).
strikethrough (Optional[bool]) – if provided this will enable or disable striking through text.
reset (bool) – by default a reset-all code is added at the end of the string which means that styles do not carry over. This can be disabled to compose styles.

Return type

Changed in version 8.0: A non-string message is converted to a string.

Changed in version 8.0: Added support for 256 and RGB color codes.

Changed in version 8.0: Added the strikethrough, italic, and overline parameters.

Changelog

Changed in version 7.0: Added support for bright colors.

New in version 2.0.

click.unstyle(text)¶

Removes ANSI styling information from a string. Usually it’s not necessary to use this function as Click’s echo function will automatically remove styling if necessary.

Changelog

New in version 2.0.

Parameters: text (str) – the text to remove style information from.
Return type: str

click.secho(message=None, file=None, nl=True, err=False, color=None, **styles)¶

This function combines echo() and style() into one call. As such the following two calls are the same:

click.secho('Hello World!', fg='green')
click.echo(click.style('Hello World!', fg='green'))

All keyword arguments are forwarded to the underlying functions depending on which one they go with.

Non-string types will be converted to str. However, bytes are passed directly to echo() without applying style. If you want to style bytes that represent text, call bytes.decode() first.

Changed in version 8.0: A non-string message is converted to a string. Bytes are passed through without style applied.

Changelog

New in version 2.0.

Parameters

message (Optional[Any]) –
file (Optional[IO]) –
nl (bool) –
err (bool) –
color (Optional[bool]) –
styles (Any) –

Return type

None

click.edit(text=None, editor=None, env=None, require_save=True, extension='.txt', filename=None)¶

Edits the given text in the defined editor. If an editor is given (should be the full path to the executable but the regular operating system search path is used for finding the executable) it overrides the detected editor. Optionally, some environment variables can be used. If the editor is closed without changes, None is returned. In case a file is edited directly the return value is always None and require_save and extension are ignored.

If the editor cannot be opened a UsageError is raised.

Note for Windows: to simplify cross-platform usage, the newlines are automatically converted from POSIX to Windows and vice versa. As such, the message here will have \n as newline markers.

Parameters

text (Optional[AnyStr]) – the text to edit.
editor (Optional[str]) – optionally the editor to use. Defaults to automatic detection.
env (Optional[Mapping[str, str]]) – environment variables to forward to the editor.
require_save (bool) – if this is true, then not saving in the editor will make the return value become None.
extension (str) – the extension to tell the editor about. This defaults to .txt but changing this might change syntax highlighting.
filename (Optional[str]) – if provided it will edit this file instead of the provided text contents. It will not use a temporary file as an indirection in that case.

Return type

Optional[AnyStr]

click.launch(url, wait=False, locate=False)¶

This function launches the given URL (or filename) in the default viewer application for this file type. If this is an executable, it might launch the executable in a new session. The return value is the exit code of the launched application. Usually, 0 indicates success.

Examples:

click.launch('https://click.palletsprojects.com/')
click.launch('/my/downloaded/file', locate=True)

Changelog

New in version 2.0.

Parameters

url (str) – URL or filename of the thing to launch.
wait (bool) – Wait for the program to exit before returning. This only works if the launched program blocks. In particular, xdg-open on Linux does not block.
locate (bool) – if this is set to True then instead of launching the application associated with the URL it will attempt to launch a file manager with the file located. This might have weird effects if the URL does not point to the filesystem.

Return type

int

click.getchar(echo=False)¶

Fetches a single character from the terminal and returns it. This will always return a unicode character and under certain rare circumstances this might return more than one character. The situations which more than one character is returned is when for whatever reason multiple characters end up in the terminal buffer or standard input was not actually a terminal.

Note that this will always read from the terminal, even if something is piped into the standard input.

Note for Windows: in rare cases when typing non-ASCII characters, this function might wait for a second character and then return both at once. This is because certain Unicode characters look like special-key markers.

Changelog

New in version 2.0.

Parameters: echo (bool) – if set to True, the character read will also show up on the terminal. The default is to not show it.
Return type: str

click.pause(info=None, err=False)¶

This command stops execution and waits for the user to press any key to continue. This is similar to the Windows batch “pause” command. If the program is not run through a terminal, this command will instead do nothing.

Changelog

New in version 4.0: Added the err parameter.

New in version 2.0.

Parameters

info (Optional[str]) – The message to print before pausing. Defaults to "Press any key to continue...".
err (bool) – if set to message goes to stderr instead of stdout, the same as with echo.

Return type

None

click.get_terminal_size()¶

Returns the current size of the terminal as tuple in the form (width, height) in columns and rows.

Deprecated since version 8.0: Will be removed in Click 8.1. Use shutil.get_terminal_size() instead.

Return type: os.terminal_size

click.get_binary_stream(name)¶

Returns a system stream for byte processing.

Parameters: name (te.Literal['stdin', 'stdout', 'stderr']) – the name of the stream to open. Valid names are 'stdin', 'stdout' and 'stderr'
Return type: BinaryIO

click.get_text_stream(name, encoding=None, errors='strict')¶

Returns a system stream for text processing. This usually returns a wrapped stream around a binary stream returned from get_binary_stream() but it also can take shortcuts for already correctly configured streams.

Parameters

name (te.Literal['stdin', 'stdout', 'stderr']) – the name of the stream to open. Valid names are 'stdin', 'stdout' and 'stderr'
encoding (Optional[str]) – overrides the detected default encoding.
errors (Optional[str]) – overrides the default error mode.

Return type

TextIO

click.open_file(filename, mode='r', encoding=None, errors='strict', lazy=False, atomic=False)¶

Open a file, with extra behavior to handle '-' to indicate a standard stream, lazy open on write, and atomic write. Similar to the behavior of the File param type.

If '-' is given to open stdout or stdin, the stream is wrapped so that using it in a context manager will not close it. This makes it possible to use the function without accidentally closing a standard stream:

with open_file(filename) as f:
    ...

Parameters

filename (str) – The name of the file to open, or '-' for stdin/stdout.
mode (str) – The mode in which to open the file.
encoding (Optional[str]) – The encoding to decode or encode a file opened in text mode.
errors (Optional[str]) – The error handling mode.
lazy (bool) – Wait to open the file until it is accessed. For read mode, the file is temporarily opened to raise access errors early, then closed until it is read again.
atomic (bool) – Write to a temporary file and replace the given file on close.

Return type

IO

Changelog

New in version 3.0.

click.get_app_dir(app_name, roaming=True, force_posix=False)¶

Returns the config folder for the application. The default behavior is to return whatever is most appropriate for the operating system.

To give you an idea, for an app called "Foo Bar", something like the following folders could be returned:

Mac OS X:: ~/Library/Application Support/Foo Bar
Mac OS X (POSIX):: ~/.foo-bar
Unix:: ~/.config/foo-bar
Unix (POSIX):: ~/.foo-bar
Windows (roaming):: C:\Users\<user>\AppData\Roaming\Foo Bar
Windows (not roaming):: C:\Users\<user>\AppData\Local\Foo Bar

Changelog

New in version 2.0.

Parameters

app_name (str) – the application name. This should be properly capitalized and can contain whitespace.
roaming (bool) – controls if the folder should be roaming or not on Windows. Has no affect otherwise.
force_posix (bool) – if this is set to True then on any POSIX system the folder will be stored in the home folder with a leading dot instead of the XDG config home or darwin’s application support folder.

Return type

click.format_filename(filename, shorten=False)¶

Formats a filename for user display. The main purpose of this function is to ensure that the filename can be displayed at all. This will decode the filename to unicode if necessary in a way that it will not fail. Optionally, it can shorten the filename to not include the full path to the filename.

Parameters

filename (Union[str, bytes, os.PathLike]) – formats a filename for UI display. This will also convert the filename into unicode without failing.
shorten (bool) – this optionally shortens the filename to strip of the path that leads up to it.

Return type

Commands¶

class click.BaseCommand(name, context_settings=None)¶

The base command implements the minimal API contract of commands. Most code will never use this as it does not implement a lot of useful functionality but it can act as the direct subclass of alternative parsing methods that do not depend on the Click parser.

For instance, this can be used to bridge Click and other systems like argparse or docopt.

Because base commands do not implement a lot of the API that other parts of Click take for granted, they are not supported for all operations. For instance, they cannot be used with the decorators usually and they have no built-in callback system.

Changelog

Changed in version 2.0: Added the context_settings parameter.

Parameters

name (Optional[str]) – the name of the command to use unless a group overrides it.
context_settings (Optional[Dict[str, Any]]) – an optional dictionary with defaults that are passed to the context object.

Return type

None

allow_extra_args = False¶: the default for the Context.allow_extra_args flag.

allow_interspersed_args = True¶: the default for the Context.allow_interspersed_args flag.

context_class¶: alias of click.core.Context

context_settings: Dict[str, Any]¶: an optional dictionary with defaults passed to the context.

ignore_unknown_options = False¶: the default for the Context.ignore_unknown_options flag.

invoke(ctx)¶

Given a context, this invokes the command. The default implementation is raising a not implemented error.

Parameters: ctx (click.core.Context) –
Return type: Any

main(args: Optional[Sequence[str]] = None, prog_name: Optional[str] = None, complete_var: Optional[str] = None, standalone_mode: te.Literal[True] = True, **extra: Any) → te.NoReturn¶

main(args: Optional[Sequence[str]] = None, prog_name: Optional[str] = None, complete_var: Optional[str] = None, standalone_mode: bool = True, **extra: Any) → Any

This is the way to invoke a script with all the bells and whistles as a command line application. This will always terminate the application after a call. If this is not wanted, SystemExit needs to be caught.

This method is also available by directly calling the instance of a Command.

Parameters

args – the arguments that should be used for parsing. If not provided, sys.argv[1:] is used.
prog_name – the program name that should be used. By default the program name is constructed by taking the file name from sys.argv[0].
complete_var – the environment variable that controls the bash completion support. The default is "_<prog_name>_COMPLETE" with prog_name in uppercase.
standalone_mode – the default behavior is to invoke the script in standalone mode. Click will then handle exceptions and convert them into error messages and the function will never return but shut down the interpreter. If this is set to False they will be propagated to the caller and the return value of this function is the return value of invoke().
windows_expand_args – Expand glob patterns, user dir, and env vars in command line args on Windows.
extra – extra keyword arguments are forwarded to the context constructor. See Context for more information.

Changed in version 8.0.1: Added the windows_expand_args parameter to allow disabling command line arg expansion on Windows.

Changed in version 8.0: When taking arguments from sys.argv on Windows, glob patterns, user dir, and env vars are expanded.

Changelog

Changed in version 3.0: Added the standalone_mode parameter.

make_context(info_name, args, parent=None, **extra)¶

This function when given an info name and arguments will kick off the parsing and create a new Context. It does not invoke the actual command callback though.

To quickly customize the context class used without overriding this method, set the context_class attribute.

Parameters

info_name (Optional[str]) – the info name for this invocation. Generally this is the most descriptive name for the script or command. For the toplevel script it’s usually the name of the script, for commands below it it’s the name of the command.
args (List[str]) – the arguments to parse as list of strings.
parent (Optional[click.core.Context]) – the parent context if available.
extra (Any) – extra keyword arguments forwarded to the context constructor.

Return type

click.core.Context

Changed in version 8.0: Added the context_class attribute.

name¶: the name the command thinks it has. Upon registering a command on a Group the group will default the command name with this information. You should instead use the Context's info_name attribute.

parse_args(ctx, args)¶

Given a context and a list of arguments this creates the parser and parses the arguments, then modifies the context as necessary. This is automatically invoked by make_context().

Parameters

ctx (click.core.Context) –
args (List[str]) –

Return type

List[str]

shell_complete(ctx, incomplete)¶

Return a list of completions for the incomplete value. Looks at the names of chained multi-commands.

Any command could be part of a chained multi-command, so sibling commands are valid at any point during command completion. Other command classes will return more completions.

Parameters

ctx (click.core.Context) – Invocation context for this command.
incomplete (str) – Value being completed. May be empty.

Return type

New in version 8.0.

to_info_dict(ctx)¶

Gather information that could be useful for a tool generating user-facing documentation. This traverses the entire structure below this command.

Use click.Context.to_info_dict() to traverse the entire CLI structure.

Parameters: ctx (click.core.Context) – A Context representing this command.
Return type: Dict[str, Any]

New in version 8.0.

class click.Command(name, context_settings=None, callback=None, params=None, help=None, epilog=None, short_help=None, options_metavar='[OPTIONS]', add_help_option=True, no_args_is_help=False, hidden=False, deprecated=False)¶

Commands are the basic building block of command line interfaces in Click. A basic command handles command line parsing and might dispatch more parsing to commands nested below it.

Changed in version 8.0: Added repr showing the command name

Changelog

Changed in version 7.1: Added the no_args_is_help parameter.

Changed in version 2.0: Added the context_settings parameter.

Parameters

name (Optional[str]) – the name of the command to use unless a group overrides it.
context_settings (Dict[str, Any]) – an optional dictionary with defaults that are passed to the context object.
callback (Optional[Callable[[...], Any]]) – the callback to invoke. This is optional.
params (Optional[List[Parameter]]) – the parameters to register with this command. This can be either Option or Argument objects.
help (Optional[str]) – the help string to use for this command.
epilog (Optional[str]) – like the help string but it’s printed at the end of the help page after everything else.
short_help (Optional[str]) – the short help to use for this command. This is shown on the command listing of the parent command.
add_help_option (bool) – by default each command registers a --help option. This can be disabled by this parameter.
no_args_is_help (bool) – this controls what happens if no arguments are provided. This option is disabled by default. If enabled this will add --help as argument if no arguments are passed
hidden (bool) – hide this command from help outputs.
deprecated (bool) – issues a message indicating that the command is deprecated.
options_metavar (Optional[str]) –

Return type

None

callback¶: the callback to execute when the command fires. This might be None in which case nothing happens.

collect_usage_pieces(ctx)¶

Returns all the pieces that go into the usage line and returns it as a list of strings.

Parameters: ctx (click.core.Context) –
Return type: List[str]

format_epilog(ctx, formatter)¶

Writes the epilog into the formatter if it exists.

Parameters

ctx (click.core.Context) –
formatter (click.formatting.HelpFormatter) –

Return type

None

format_help(ctx, formatter)¶

Writes the help into the formatter if it exists.

This is a low-level method called by get_help().

This calls the following methods:

format_usage()
format_help_text()
format_options()
format_epilog()

Parameters

ctx (click.core.Context) –
formatter (click.formatting.HelpFormatter) –

Return type

None

format_help_text(ctx, formatter)¶

Writes the help text to the formatter if it exists.

Parameters

ctx (click.core.Context) –
formatter (click.formatting.HelpFormatter) –

Return type

None

format_options(ctx, formatter)¶

Writes all the options into the formatter if they exist.

Parameters

ctx (click.core.Context) –
formatter (click.formatting.HelpFormatter) –

Return type

None

format_usage(ctx, formatter)¶

Writes the usage line into the formatter.

This is a low-level method called by get_usage().

Parameters

ctx (click.core.Context) –
formatter (click.formatting.HelpFormatter) –

Return type

None

get_help(ctx)¶

Formats the help into a string and returns it.

Calls format_help() internally.

Parameters: ctx (click.core.Context) –
Return type: str

get_help_option(ctx)¶

Returns the help option object.

Parameters: ctx (click.core.Context) –
Return type: Optional[click.core.Option]

get_help_option_names(ctx)¶

Returns the names for the help option.

Parameters: ctx (click.core.Context) –
Return type: List[str]

get_short_help_str(limit=45)¶

Gets short help for the command or makes it by shortening the long help string.

Parameters: limit (int) –
Return type: str

get_usage(ctx)¶

Formats the usage line into a string and returns it.

Calls format_usage() internally.

Parameters: ctx (click.core.Context) –
Return type: str

invoke(ctx)¶

Given a context, this invokes the attached callback (if it exists) in the right way.

Parameters: ctx (click.core.Context) –
Return type: Any

make_parser(ctx)¶

Creates the underlying option parser for this command.

Parameters: ctx (click.core.Context) –
Return type: click.parser.OptionParser

params: List[click.core.Parameter]¶: the list of parameters for this command in the order they should show up in the help page and execute. Eager parameters will automatically be handled before non eager ones.

parse_args(ctx, args)¶

Given a context and a list of arguments this creates the parser and parses the arguments, then modifies the context as necessary. This is automatically invoked by make_context().

Parameters

ctx (click.core.Context) –
args (List[str]) –

Return type

List[str]

shell_complete(ctx, incomplete)¶

Return a list of completions for the incomplete value. Looks at the names of options and chained multi-commands.

Parameters

ctx (click.core.Context) – Invocation context for this command.
incomplete (str) – Value being completed. May be empty.

Return type

Optional[click.core.Command]

New in version 8.0.

to_info_dict(ctx)¶

Gather information that could be useful for a tool generating user-facing documentation. This traverses the entire structure below this command.

Use click.Context.to_info_dict() to traverse the entire CLI structure.

Parameters: ctx (click.core.Context) – A Context representing this command.
Return type: Dict[str, Any]

New in version 8.0.

class click.MultiCommand(name=None, invoke_without_command=False, no_args_is_help=None, subcommand_metavar=None, chain=False, result_callback=None, **attrs)¶

A multi command is the basic implementation of a command that dispatches to subcommands. The most common version is the Group.

Parameters

invoke_without_command (bool) – this controls how the multi command itself is invoked. By default it’s only invoked if a subcommand is provided.
no_args_is_help (Optional[bool]) – this controls what happens if no arguments are provided. This option is enabled by default if invoke_without_command is disabled or disabled if it’s enabled. If enabled this will add --help as argument if no arguments are passed.
subcommand_metavar (Optional[str]) – the string that is used in the documentation to indicate the subcommand place.
chain (bool) – if this is set to True chaining of multiple subcommands is enabled. This restricts the form of commands in that they cannot have optional arguments but it allows multiple commands to be chained together.
result_callback (Optional[Callable[[...], Any]]) – The result callback to attach to this multi command. This can be set or changed later with the result_callback() decorator.
name (Optional[str]) –
attrs (Any) –

Return type

None

collect_usage_pieces(ctx)¶

Returns all the pieces that go into the usage line and returns it as a list of strings.

Parameters: ctx (click.core.Context) –
Return type: List[str]

format_commands(ctx, formatter)¶

Extra format methods for multi methods that adds all the commands after the options.

Parameters

ctx (click.core.Context) –
formatter (click.formatting.HelpFormatter) –

Return type

None

format_options(ctx, formatter)¶

Writes all the options into the formatter if they exist.

Parameters

ctx (click.core.Context) –
formatter (click.formatting.HelpFormatter) –

Return type

None

get_command(ctx, cmd_name)¶

Given a context and a command name, this returns a Command object if it exists or returns None.

Parameters

ctx (click.core.Context) –
cmd_name (str) –

Return type

invoke(ctx)¶

Given a context, this invokes the attached callback (if it exists) in the right way.

Parameters: ctx (click.core.Context) –
Return type: Any

list_commands(ctx)¶

Returns a list of subcommand names in the order they should appear.

Parameters: ctx (click.core.Context) –
Return type: List[str]

parse_args(ctx, args)¶

Given a context and a list of arguments this creates the parser and parses the arguments, then modifies the context as necessary. This is automatically invoked by make_context().

Parameters

ctx (click.core.Context) –
args (List[str]) –

Return type

List[str]

result_callback(replace=False)¶

Adds a result callback to the command. By default if a result callback is already registered this will chain them but this can be disabled with the replace parameter. The result callback is invoked with the return value of the subcommand (or the list of return values from all subcommands if chaining is enabled) as well as the parameters as they would be passed to the main callback.

Example:

@click.group()
@click.option('-i', '--input', default=23)
def cli(input):
    return 42

@cli.result_callback()
def process_result(result, input):
    return result + input

Parameters: replace (bool) – if set to True an already existing result callback will be removed.
Return type: Callable[[click.core.F], click.core.F]

Changed in version 8.0: Renamed from resultcallback.

Changelog

New in version 3.0.

shell_complete(ctx, incomplete)¶

Return a list of completions for the incomplete value. Looks at the names of options, subcommands, and chained multi-commands.

Parameters

ctx (click.core.Context) – Invocation context for this command.
incomplete (str) – Value being completed. May be empty.

Return type

Optional[click.core.Command]

New in version 8.0.

to_info_dict(ctx)¶

Gather information that could be useful for a tool generating user-facing documentation. This traverses the entire structure below this command.

Use click.Context.to_info_dict() to traverse the entire CLI structure.

Parameters: ctx (click.core.Context) – A Context representing this command.
Return type: Dict[str, Any]

New in version 8.0.

class click.Group(name=None, commands=None, **attrs)¶

A group allows a command to have subcommands attached. This is the most common way to implement nesting in Click.

Parameters

name (Optional[str]) – The name of the group command.
commands (Optional[Union[Dict[str, click.core.Command], Sequence[click.core.Command]]]) – A dict mapping names to Command objects. Can also be a list of Command, which will use Command.name to create the dict.
attrs (Any) – Other command arguments described in MultiCommand, Command, and BaseCommand.

Return type

None

Changed in version 8.0: The commmands argument can be a list of command objects.

add_command(cmd, name=None)¶

Registers another Command with this group. If the name is not provided, the name of the command is used.

Parameters

cmd (click.core.Command) –
name (Optional[str]) –

Return type

None

command(*args, **kwargs)¶

A shortcut decorator for declaring and attaching a command to the group. This takes the same arguments as command() and immediately registers the created command with this group by calling add_command().

To customize the command class used, set the command_class attribute.

Changed in version 8.0: Added the command_class attribute.

Parameters

args (Any) –
kwargs (Any) –

Return type

Callable[[Callable[[…], Any]], click.core.Command]

command_class: Optional[Type[click.core.Command]] = None¶: If set, this is used by the group’s command() decorator as the default Command class. This is useful to make all subcommands use a custom command class.

New in version 8.0.

commands: Dict[str, click.core.Command]¶: The registered subcommands by their exported names.

get_command(ctx, cmd_name)¶

Given a context and a command name, this returns a Command object if it exists or returns None.

Parameters

ctx (click.core.Context) –
cmd_name (str) –

Return type

group(*args, **kwargs)¶

A shortcut decorator for declaring and attaching a group to the group. This takes the same arguments as group() and immediately registers the created group with this group by calling add_command().

To customize the group class used, set the group_class attribute.

Changed in version 8.0: Added the group_class attribute.

Parameters

args (Any) –
kwargs (Any) –

Return type

Callable[[Callable[[…], Any]], click.core.Group]

group_class: Optional[Union[Type[click.core.Group], Type[type]]] = None¶

If set, this is used by the group’s group() decorator as the default Group class. This is useful to make all subgroups use a custom group class.

If set to the special value type (literally group_class = type), this group’s class will be used as the default class. This makes a custom group class continue to make custom groups.

New in version 8.0.

list_commands(ctx)¶

Returns a list of subcommand names in the order they should appear.

Parameters: ctx (click.core.Context) –
Return type: List[str]

class click.CommandCollection(name=None, sources=None, **attrs)¶

A command collection is a multi command that merges multiple multi commands together into one. This is a straightforward implementation that accepts a list of different multi commands as sources and provides all the commands for each of them.

Parameters

name (Optional[str]) –
sources (Optional[List[click.core.MultiCommand]]) –
attrs (Any) –

Return type

None

add_source(multi_cmd)¶

Adds a new multi command to the chain dispatcher.

Parameters: multi_cmd (click.core.MultiCommand) –
Return type: None

get_command(ctx, cmd_name)¶

Given a context and a command name, this returns a Command object if it exists or returns None.

Parameters

ctx (click.core.Context) –
cmd_name (str) –

Return type

Optional[click.core.Command]

list_commands(ctx)¶

Returns a list of subcommand names in the order they should appear.

Parameters: ctx (click.core.Context) –
Return type: List[str]

sources: List[click.core.MultiCommand]¶: The list of registered multi commands.

Parameters¶

class click.Parameter(param_decls=None, type=None, required=False, default=None, callback=None, nargs=None, multiple=False, metavar=None, expose_value=True, is_eager=False, envvar=None, shell_complete=None, autocompletion=None)¶

A parameter to a command comes in two versions: they are either Options or Arguments. Other subclasses are currently not supported by design as some of the internals for parsing are intentionally not finalized.

Some settings are supported by both options and arguments.

Parameters

param_decls (Optional[Sequence[str]]) – the parameter declarations for this option or argument. This is a list of flags or argument names.
type (Optional[Union[click.types.ParamType, Any]]) – the type that should be used. Either a ParamType or a Python type. The later is converted into the former automatically if supported.
required (bool) – controls if this is optional or not.
default (Optional[Union[Any, Callable[[], Any]]]) – the default value if omitted. This can also be a callable, in which case it’s invoked when the default is needed without any arguments.
callback (Optional[Callable[[click.core.Context, Parameter, Any], Any]]) – A function to further process or validate the value after type conversion. It is called as f(ctx, param, value) and must return the value. It is called for all sources, including prompts.
nargs (Optional[int]) – the number of arguments to match. If not 1 the return value is a tuple instead of single value. The default for nargs is 1 (except if the type is a tuple, then it’s the arity of the tuple). If nargs=-1, all remaining parameters are collected.
metavar (Optional[str]) – how the value is represented in the help page.
expose_value (bool) – if this is True then the value is passed onwards to the command callback and stored on the context, otherwise it’s skipped.
is_eager (bool) – eager values are processed before non eager ones. This should not be set for arguments or it will inverse the order of processing.
envvar (Optional[Union[Sequence[str], str]]) – a string or list of strings that are environment variables that should be checked.
shell_complete (Optional[Callable[[click.core.Context, Parameter, str], Union[List[CompletionItem], List[str]]]]) – A function that returns custom shell completions. Used instead of the param’s type completion if given. Takes ctx, param, incomplete and must return a list of CompletionItem or a list of strings.
multiple (bool) –
autocompletion (Optional[Callable[[click.core.Context, List[str], str], List[Union[Tuple[str, str], str]]]]) –

Return type

None

Changed in version 8.0: process_value validates required parameters and bounded nargs, and invokes the parameter callback before returning the value. This allows the callback to validate prompts. full_process_value is removed.

Changed in version 8.0: autocompletion is renamed to shell_complete and has new semantics described above. The old name is deprecated and will be removed in 8.1, until then it will be wrapped to match the new requirements.

Changed in version 8.0: For multiple=True, nargs>1, the default must be a list of tuples.

Changed in version 8.0: Setting a default is no longer required for nargs>1, it will default to None. multiple=True or nargs=-1 will default to ().

Changelog

Changed in version 7.1: Empty environment variables are ignored rather than taking the empty string value. This makes it possible for scripts to clear variables if they can’t unset them.

Changed in version 2.0: Changed signature for parameter callback to also be passed the parameter. The old callback format will still work, but it will raise a warning to give you a chance to migrate the code easier.

get_default(ctx: click.core.Context, call: te.Literal[True] = True) → Optional[Any]¶

get_default(ctx: click.core.Context, call: bool = True) → Optional[Union[Any, Callable[[], Any]]]

Get the default for the parameter. Tries Context.lookup_default() first, then the local default.

Parameters

ctx – Current context.
call – If the default is a callable, call it. Disable to return the callable instead.

Changed in version 8.0.2: Type casting is no longer performed when getting a default.

Changed in version 8.0.1: Type casting can fail in resilient parsing mode. Invalid defaults will not prevent showing help text.

Changed in version 8.0: Looks at ctx.default_map first.

Changed in version 8.0: Added the call parameter.

get_error_hint(ctx)¶

Get a stringified version of the param for use in error messages to indicate which param caused the error.

Parameters: ctx (click.core.Context) –
Return type: str

property human_readable_name: str¶: Returns the human readable name of this parameter. This is the same as the name for options, but the metavar for arguments.

shell_complete(ctx, incomplete)¶

Return a list of completions for the incomplete value. If a shell_complete function was given during init, it is used. Otherwise, the type shell_complete() function is used.

Parameters

ctx (click.core.Context) – Invocation context for this command.
incomplete (str) – Value being completed. May be empty.

Return type

New in version 8.0.

to_info_dict()¶

Gather information that could be useful for a tool generating user-facing documentation.

Use click.Context.to_info_dict() to traverse the entire CLI structure.

New in version 8.0.

Return type: Dict[str, Any]

type_cast_value(ctx, value)¶

Convert and validate a value against the option’s type, multiple, and nargs.

Parameters

ctx (click.core.Context) –
value (Any) –

Return type

class click.Option(param_decls=None, show_default=False, prompt=False, confirmation_prompt=False, prompt_required=True, hide_input=False, is_flag=None, flag_value=None, multiple=False, count=False, allow_from_autoenv=True, type=None, help=None, hidden=False, show_choices=True, show_envvar=False, **attrs)¶

Options are usually optional values on the command line and have some extra features that arguments don’t have.

All other parameters are passed onwards to the parameter constructor.

Parameters

show_default (Union[bool, str]) – controls if the default value should be shown on the help page. Normally, defaults are not shown. If this value is a string, it shows the string instead of the value. This is particularly useful for dynamic options.
show_envvar (bool) – controls if an environment variable should be shown on the help page. Normally, environment variables are not shown.
prompt (Union[bool, str]) – if set to True or a non empty string then the user will be prompted for input. If set to True the prompt will be the option name capitalized.
confirmation_prompt (Union[bool, str]) – Prompt a second time to confirm the value if it was prompted for. Can be set to a string instead of True to customize the message.
prompt_required (bool) – If set to False, the user will be prompted for input only when the option was specified as a flag without a value.
hide_input (bool) – if this is True then the input on the prompt will be hidden from the user. This is useful for password input.
is_flag (Optional[bool]) – forces this option to act as a flag. The default is auto detection.
flag_value (Optional[Any]) – which value should be used for this flag if it’s enabled. This is set to a boolean automatically if the option string contains a slash to mark two options.
multiple (bool) – if this is set to True then the argument is accepted multiple times and recorded. This is similar to nargs in how it works but supports arbitrary number of arguments.
count (bool) – this flag makes an option increment an integer.
allow_from_autoenv (bool) – if this is enabled then the value of this parameter will be pulled from an environment variable in case a prefix is defined on the context.
help (Optional[str]) – the help string.
hidden (bool) – hide this option from help outputs.
param_decls (Optional[Sequence[str]]) –
type (Optional[Union[click.types.ParamType, Any]]) –
show_choices (bool) –
attrs (Any) –

Return type

None

Changed in version 8.0.1: type is detected from flag_value if given.

class click.Argument(param_decls, required=None, **attrs)¶

Arguments are positional parameters to a command. They generally provide fewer features than options but can have infinite nargs and are required by default.

All parameters are passed onwards to the parameter constructor.

Parameters

param_decls (Sequence[str]) –
required (Optional[bool]) –
attrs (Any) –

Return type

None

Context¶

class click.Context(command, parent=None, info_name=None, obj=None, auto_envvar_prefix=None, default_map=None, terminal_width=None, max_content_width=None, resilient_parsing=False, allow_extra_args=None, allow_interspersed_args=None, ignore_unknown_options=None, help_option_names=None, token_normalize_func=None, color=None, show_default=None)¶

The context is a special internal object that holds state relevant for the script execution at every single level. It’s normally invisible to commands unless they opt-in to getting access to it.

The context is useful as it can pass internal objects around and can control special execution features such as reading data from environment variables.

A context can be used as context manager in which case it will call close() on teardown.

Parameters

command (Command) – the command class for this context.
parent (Optional[Context]) – the parent context.
info_name (Optional[str]) – the info name for this invocation. Generally this is the most descriptive name for the script or command. For the toplevel script it is usually the name of the script, for commands below it it’s the name of the script.
obj (Optional[Any]) – an arbitrary object of user data.
auto_envvar_prefix (Optional[str]) – the prefix to use for automatic environment variables. If this is None then reading from environment variables is disabled. This does not affect manually set environment variables which are always read.
default_map (Optional[Dict[str, Any]]) – a dictionary (like object) with default values for parameters.
terminal_width (Optional[int]) – the width of the terminal. The default is inherit from parent context. If no context defines the terminal width then auto detection will be applied.
max_content_width (Optional[int]) – the maximum width for content rendered by Click (this currently only affects help pages). This defaults to 80 characters if not overridden. In other words: even if the terminal is larger than that, Click will not format things wider than 80 characters by default. In addition to that, formatters might add some safety mapping on the right.
resilient_parsing (bool) – if this flag is enabled then Click will parse without any interactivity or callback invocation. Default values will also be ignored. This is useful for implementing things such as completion support.
allow_extra_args (Optional[bool]) – if this is set to True then extra arguments at the end will not raise an error and will be kept on the context. The default is to inherit from the command.
allow_interspersed_args (Optional[bool]) – if this is set to False then options and arguments cannot be mixed. The default is to inherit from the command.
ignore_unknown_options (Optional[bool]) – instructs click to ignore options it does not know and keeps them for later processing.
help_option_names (Optional[List[str]]) – optionally a list of strings that define how the default help parameter is named. The default is ['--help'].
token_normalize_func (Optional[Callable[[str], str]]) – an optional function that is used to normalize tokens (options, choices, etc.). This for instance can be used to implement case insensitive behavior.
color (Optional[bool]) – controls if the terminal supports ANSI colors or not. The default is autodetection. This is only needed if ANSI codes are used in texts that Click prints which is by default not the case. This for instance would affect help output.
show_default (Optional[bool]) – Show defaults for all options. If not set, defaults to the value from a parent context. Overrides an option’s show_default argument.

Return type

None

Changed in version 8.0: The show_default parameter defaults to the value from the parent context.

Changelog

Changed in version 7.1: Added the show_default parameter.

Changed in version 4.0: Added the color, ignore_unknown_options, and max_content_width parameters.

Changed in version 3.0: Added the allow_extra_args and allow_interspersed_args parameters.

Changed in version 2.0: Added the resilient_parsing, help_option_names, and token_normalize_func parameters.

abort()¶

Aborts the script.

Return type: te.NoReturn

allow_extra_args¶: Indicates if the context allows extra args or if it should fail on parsing.

Changelog

New in version 3.0.

allow_interspersed_args: bool¶: Indicates if the context allows mixing of arguments and options or not.

Changelog

New in version 3.0.

args: List[str]¶: the leftover arguments.

call_on_close(f)¶

Register a function to be called when the context tears down.

This can be used to close resources opened during the script execution. Resources that support Python’s context manager protocol which would be used in a with statement should be registered with with_resource() instead.

Parameters: f (Callable[[...], Any]) – The function to execute on teardown.
Return type: Callable[[…], Any]

close()¶

Invoke all close callbacks registered with call_on_close(), and exit all context managers entered with with_resource().

Return type: None

color: Optional[bool]¶: Controls if styling output is wanted or not.

command¶: the Command for this context.

property command_path: str¶: The computed command path. This is used for the usage information on the help page. It’s automatically created by combining the info names of the chain of contexts to the root.

ensure_object(object_type)¶

Like find_object() but sets the innermost object to a new instance of object_type if it does not exist.

Parameters: object_type (Type[click.core.V]) –
Return type: click.core.V

exit(code=0)¶

Exits the application with a given exit code.

Parameters: code (int) –
Return type: te.NoReturn

fail(message)¶

Aborts the execution of the program with a specific error message.

Parameters: message (str) – the error message to fail with.
Return type: te.NoReturn

find_object(object_type)¶

Finds the closest object of a given type.

Parameters: object_type (Type[click.core.V]) –
Return type: Optional[click.core.V]

find_root()¶

Finds the outermost context.

Return type: click.core.Context

formatter_class¶: alias of click.formatting.HelpFormatter

forward(_Context__cmd, *args, **kwargs)¶

Similar to invoke() but fills in default keyword arguments from the current context if the other command expects it. This cannot invoke callbacks directly, only other commands.

Changed in version 8.0: All kwargs are tracked in params so they will be passed if forward is called at multiple levels.

Parameters

_Context__cmd (click.core.Command) –
args (Any) –
kwargs (Any) –

Return type

get_help()¶

Helper method to get formatted help page for the current context and command.

Return type: str

get_parameter_source(name)¶

Get the source of a parameter. This indicates the location from which the value of the parameter was obtained.

This can be useful for determining when a user specified a value on the command line that is the same as the default value. It will be DEFAULT only if the value was actually taken from the default.

Parameters: name (str) – The name of the parameter.
Return type: ParameterSource

Changed in version 8.0: Returns None if the parameter was not provided from any source.

get_usage()¶

Helper method to get formatted usage string for the current context and command.

Return type: str

help_option_names: List[str]¶: The names for the help options.

ignore_unknown_options: bool¶: Instructs click to ignore options that a command does not understand and will store it on the context for later processing. This is primarily useful for situations where you want to call into external programs. Generally this pattern is strongly discouraged because it’s not possibly to losslessly forward all arguments.

Changelog

New in version 4.0.

info_name¶: the descriptive information name

invoke(_Context__callback, *args, **kwargs)¶

Invokes a command callback in exactly the way it expects. There are two ways to invoke this method:

the first argument can be a callback and all other arguments and keyword arguments are forwarded directly to the function.
the first argument is a click command object. In that case all arguments are forwarded as well but proper click parameters (options and click arguments) must be keyword arguments and Click will fill in defaults.

Note that before Click 3.2 keyword arguments were not properly filled in against the intention of this code and no context was created. For more information about this change and why it was done in a bugfix release see Upgrading to 3.2.

Changed in version 8.0: All kwargs are tracked in params so they will be passed if forward() is called at multiple levels.

Parameters

_Context__callback (Union[click.core.Command, Callable[[...], Any]]) –
args (Any) –
kwargs (Any) –

Return type

invoked_subcommand: Optional[str]¶

This flag indicates if a subcommand is going to be executed. A group callback can use this information to figure out if it’s being executed directly or because the execution flow passes onwards to a subcommand. By default it’s None, but it can be the name of the subcommand to execute.

If chaining is enabled this will be set to '*' in case any commands are executed. It is however not possible to figure out which ones. If you require this knowledge you should use a result_callback().

lookup_default(name: str, call: te.Literal[True] = True) → Optional[Any]¶

lookup_default(name: str, call: te.Literal[False] = True) → Optional[Union[Any, Callable[[], Any]]]

Get the default for a parameter from default_map.

Parameters

name – Name of the parameter.
call – If the default is a callable, call it. Disable to return the callable instead.

Changed in version 8.0: Added the call parameter.

make_formatter()¶

Creates the HelpFormatter for the help and usage output.

To quickly customize the formatter class used without overriding this method, set the formatter_class attribute.

Changed in version 8.0: Added the formatter_class attribute.

Return type: click.formatting.HelpFormatter

max_content_width: Optional[int]¶: The maximum width of formatted content (None implies a sensible default which is 80 for most things).

property meta: Dict[str, Any]¶

This is a dictionary which is shared with all the contexts that are nested. It exists so that click utilities can store some state here if they need to. It is however the responsibility of that code to manage this dictionary well.

The keys are supposed to be unique dotted strings. For instance module paths are a good choice for it. What is stored in there is irrelevant for the operation of click. However what is important is that code that places data here adheres to the general semantics of the system.

Example usage:

LANG_KEY = f'{__name__}.lang'

def set_language(value):
    ctx = get_current_context()
    ctx.meta[LANG_KEY] = value

def get_language():
    return get_current_context().meta.get(LANG_KEY, 'en_US')

Changelog

New in version 5.0.

obj: Any¶: the user object stored.

params: Dict[str, Any]¶: Map of parameter names to their parsed values. Parameters with expose_value=False are not stored.

parent¶: the parent context or None if none exists.

protected_args: List[str]¶: protected arguments. These are arguments that are prepended to args when certain parsing scenarios are encountered but must be never propagated to another arguments. This is used to implement nested parsing.

resilient_parsing: bool¶: Indicates if resilient parsing is enabled. In that case Click will do its best to not cause any failures and default values will be ignored. Useful for completion.

scope(cleanup=True)¶

This helper method can be used with the context object to promote it to the current thread local (see get_current_context()). The default behavior of this is to invoke the cleanup functions which can be disabled by setting cleanup to False. The cleanup functions are typically used for things such as closing file handles.

If the cleanup is intended the context object can also be directly used as a context manager.

Example usage:

with ctx.scope():
    assert get_current_context() is ctx

This is equivalent:

with ctx:
    assert get_current_context() is ctx

Changelog

New in version 5.0.

Parameters: cleanup (bool) – controls if the cleanup functions should be run or not. The default is to run these functions. In some situations the context only wants to be temporarily pushed in which case this can be disabled. Nested pushes automatically defer the cleanup.
Return type: Iterator[click.core.Context]

set_parameter_source(name, source)¶

Set the source of a parameter. This indicates the location from which the value of the parameter was obtained.

Parameters

name (str) – The name of the parameter.
source (click.core.ParameterSource) – A member of ParameterSource.

Return type

None

show_default: Optional[bool]¶: Show option default values when formatting help text.

terminal_width: Optional[int]¶: The width of the terminal (None is autodetection).

to_info_dict()¶

Gather information that could be useful for a tool generating user-facing documentation. This traverses the entire CLI structure.

with Context(cli) as ctx:
    info = ctx.to_info_dict()

New in version 8.0.

Return type: Dict[str, Any]

token_normalize_func: Optional[Callable[[str], str]]¶: An optional normalization function for tokens. This is options, choices, commands etc.

with_resource(context_manager)¶

Register a resource as if it were used in a with statement. The resource will be cleaned up when the context is popped.

Uses contextlib.ExitStack.enter_context(). It calls the resource’s __enter__() method and returns the result. When the context is popped, it closes the stack, which calls the resource’s __exit__() method.

To register a cleanup function for something that isn’t a context manager, use call_on_close(). Or use something from contextlib to turn it into a context manager first.

@click.group()
@click.option("--name")
@click.pass_context
def cli(ctx):
    ctx.obj = ctx.with_resource(connect_db(name))

Parameters: context_manager (ContextManager[click.core.V]) – The context manager to enter.
Returns: Whatever context_manager.__enter__() returns.
Return type: click.core.V

New in version 8.0.

click.get_current_context(silent: te.Literal[False] = False) → Context¶

click.get_current_context(silent: bool = False) → t.Optional['Context']

Returns the current click context. This can be used as a way to access the current context object from anywhere. This is a more implicit alternative to the pass_context() decorator. This function is primarily useful for helpers such as echo() which might be interested in changing its behavior based on the current context.

To push the current context, Context.scope() can be used.

Changelog

New in version 5.0.

Parameters: silent – if set to True the return value is None if no context is available. The default behavior is to raise a RuntimeError.

class click.core.ParameterSource(value)¶

This is an Enum that indicates the source of a parameter’s value.

Use click.Context.get_parameter_source() to get the source for a parameter by name.

Changed in version 8.0: Use Enum and drop the validate method.

Changed in version 8.0: Added the PROMPT value.

COMMANDLINE = 1¶: The value was provided by the command line args.

ENVIRONMENT = 2¶: The value was provided with an environment variable.

DEFAULT = 3¶: Used the default specified by the parameter.

DEFAULT_MAP = 4¶: Used a default provided by Context.default_map.

PROMPT = 5¶: Used a prompt to confirm a default or provide a value.

Types¶

click.STRING = STRING¶

Parameters

value (Any) –
param (Optional[Parameter]) –
ctx (Optional[Context]) –

Return type

click.INT = INT¶

Parameters

value (Any) –
param (Optional[Parameter]) –
ctx (Optional[Context]) –

Return type

click.FLOAT = FLOAT¶

Parameters

value (Any) –
param (Optional[Parameter]) –
ctx (Optional[Context]) –

Return type

click.BOOL = BOOL¶

Parameters

value (Any) –
param (Optional[Parameter]) –
ctx (Optional[Context]) –

Return type

click.UUID = UUID¶

Parameters

value (Any) –
param (Optional[Parameter]) –
ctx (Optional[Context]) –

Return type

click.UNPROCESSED = UNPROCESSED¶

Parameters

value (Any) –
param (Optional[Parameter]) –
ctx (Optional[Context]) –

Return type

class click.File(mode='r', encoding=None, errors='strict', lazy=None, atomic=False)¶

Declares a parameter to be a file for reading or writing. The file is automatically closed once the context tears down (after the command finished working).

Files can be opened for reading or writing. The special value - indicates stdin or stdout depending on the mode.

By default, the file is opened for reading text data, but it can also be opened in binary mode or for writing. The encoding parameter can be used to force a specific encoding.

The lazy flag controls if the file should be opened immediately or upon first IO. The default is to be non-lazy for standard input and output streams as well as files opened for reading, lazy otherwise. When opening a file lazily for reading, it is still opened temporarily for validation, but will not be held open until first IO. lazy is mainly useful when opening for writing to avoid creating the file until it is needed.

Starting with Click 2.0, files can also be opened atomically in which case all writes go into a separate file in the same folder and upon completion the file will be moved over to the original location. This is useful if a file regularly read by other users is modified.

See File Arguments for more information.

Parameters

mode (str) –
encoding (Optional[str]) –
errors (Optional[str]) –
lazy (Optional[bool]) –
atomic (bool) –

Return type

None

class click.Path(exists=False, file_okay=True, dir_okay=True, writable=False, readable=True, resolve_path=False, allow_dash=False, path_type=None)¶

The Path type is similar to the File type, but returns the filename instead of an open file. Various checks can be enabled to validate the type of file and permissions.

Parameters

exists (bool) – The file or directory needs to exist for the value to be valid. If this is not set to True, and the file does not exist, then all further checks are silently skipped.
file_okay (bool) – Allow a file as a value.
dir_okay (bool) – Allow a directory as a value.
writable (bool) – The file or directory must be writable.
readable (bool) – The file or directory must be readable.
resolve_path (bool) – Make the value absolute and resolve any symlinks. A ~ is not expanded, as this is supposed to be done by the shell only.
allow_dash (bool) – Allow a single dash as a value, which indicates a standard stream (but does not open it). Use open_file() to handle opening this value.
path_type (Optional[Type]) – Convert the incoming path value to this type. If None, keep Python’s default, which is str. Useful to convert to pathlib.Path.

Changed in version 8.0: Allow passing type=pathlib.Path.

Changelog

Changed in version 6.0: Added the allow_dash parameter.

class click.Choice(choices, case_sensitive=True)¶

The choice type allows a value to be checked against a fixed set of supported values. All of these values have to be strings.

You should only pass a list or tuple of choices. Other iterables (like generators) may lead to surprising results.

The resulting value will always be one of the originally passed choices regardless of case_sensitive or any ctx.token_normalize_func being specified.

See Choice Options for an example.

Parameters

case_sensitive (bool) – Set to false to make choices case insensitive. Defaults to true.
choices (Sequence[str]) –

Return type

None

class click.IntRange(min=None, max=None, min_open=False, max_open=False, clamp=False)¶

Restrict an click.INT value to a range of accepted values. See Range Options.

If min or max are not passed, any value is accepted in that direction. If min_open or max_open are enabled, the corresponding boundary is not included in the range.

If clamp is enabled, a value outside the range is clamped to the boundary instead of failing.

Changed in version 8.0: Added the min_open and max_open parameters.

Parameters

min (Optional[float]) –
max (Optional[float]) –
min_open (bool) –
max_open (bool) –
clamp (bool) –

Return type

None

class click.FloatRange(min=None, max=None, min_open=False, max_open=False, clamp=False)¶

Restrict a click.FLOAT value to a range of accepted values. See Range Options.

If min or max are not passed, any value is accepted in that direction. If min_open or max_open are enabled, the corresponding boundary is not included in the range.

If clamp is enabled, a value outside the range is clamped to the boundary instead of failing. This is not supported if either boundary is marked open.

Changed in version 8.0: Added the min_open and max_open parameters.

Parameters

min (Optional[float]) –
max (Optional[float]) –
min_open (bool) –
max_open (bool) –
clamp (bool) –

Return type

None

class click.DateTime(formats=None)¶

The DateTime type converts date strings into datetime objects.

The format strings which are checked are configurable, but default to some common (non-timezone aware) ISO 8601 formats.

When specifying DateTime formats, you should only pass a list or a tuple. Other iterables, like generators, may lead to surprising results.

The format strings are processed using datetime.strptime, and this consequently defines the format strings which are allowed.

Parsing is tried using each format, in order, and the first format which parses successfully is used.

Parameters: formats (Optional[Sequence[str]]) – A list or tuple of date format strings, in the order in which they should be tried. Defaults to '%Y-%m-%d', '%Y-%m-%dT%H:%M:%S', '%Y-%m-%d %H:%M:%S'.

class click.Tuple(types)¶

The default behavior of Click is to apply a type on a value directly. This works well in most cases, except for when nargs is set to a fixed count and different types should be used for different items. In this case the Tuple type can be used. This type can only be used if nargs is set to a fixed number.

For more information see Tuples as Multi Value Options.

This can be selected by using a Python tuple literal as a type.

Parameters: types (Sequence[Union[Type, click.types.ParamType]]) – a list of types that should be used for the tuple items.
Return type: None

class click.ParamType¶

Represents the type of a parameter. Validates and converts values from the command line or Python into the correct type.

To implement a custom type, subclass and implement at least the following:

The name class attribute must be set.
Calling an instance of the type with None must return None. This is already implemented by default.
convert() must convert string values to the correct type.
convert() must accept values that are already the correct type.
It must be able to convert a value if the ctx and param arguments are None. This can occur when converting prompt input.

convert(value, param, ctx)¶

Convert the value to the correct type. This is not called if the value is None (the missing value).

This must accept string values from the command line, as well as values that are already the correct type. It may also convert other compatible types.

The param and ctx arguments may be None in certain situations, such as when converting prompt input.

If the value cannot be converted, call fail() with a descriptive message.

Parameters

value (Any) – The value to convert.
param (Optional[Parameter]) – The parameter that is using this type to convert its value. May be None.
ctx (Optional[Context]) – The current context that arrived at this value. May be None.

Return type

envvar_list_splitter: ClassVar[Optional[str]] = None¶: if a list of this type is expected and the value is pulled from a string environment variable, this is what splits it up. None means any whitespace. For all parameters the general rule is that whitespace splits them up. The exception are paths and files which are split by os.path.pathsep by default (“:” on Unix and “;” on Windows).

fail(message, param=None, ctx=None)¶

Helper method to fail with an invalid value message.

Parameters

message (str) –
param (Optional[Parameter]) –
ctx (Optional[Context]) –

Return type

t.NoReturn

get_metavar(param)¶

Returns the metavar default for this param if it provides one.

Parameters: param (Parameter) –
Return type: Optional[str]

get_missing_message(param)¶

Optionally might return extra information about a missing parameter.

Changelog

New in version 2.0.

Parameters: param (Parameter) –
Return type: Optional[str]

name: str¶: the descriptive name of this type

shell_complete(ctx, param, incomplete)¶

Return a list of CompletionItem objects for the incomplete value. Most types do not provide completions, but some do, and this allows custom types to provide custom completions as well.

Parameters

ctx (Context) – Invocation context for this command.
param (Parameter) – The parameter that is requesting completion.
incomplete (str) – Value being completed. May be empty.

Return type

New in version 8.0.

split_envvar_value(rv)¶

Given a value from an environment variable this splits it up into small chunks depending on the defined envvar list splitter.

If the splitter is set to None, which means that whitespace splits, then leading and trailing whitespace is ignored. Otherwise, leading and trailing splitters usually lead to empty items being included.

Parameters: rv (str) –
Return type: Sequence[str]

to_info_dict()¶

Gather information that could be useful for a tool generating user-facing documentation.

Use click.Context.to_info_dict() to traverse the entire CLI structure.

New in version 8.0.

Return type: Dict[str, Any]

Exceptions¶

exception click.ClickException(message)¶

An exception that Click can handle and show to the user.

Parameters: message (str) –
Return type: None

exception click.Abort¶: An internal signalling exception that signals Click to abort.

exception click.UsageError(message, ctx=None)¶

An internal exception that signals a usage error. This typically aborts any further handling.

Parameters

message (str) – the error message to display.
ctx (Optional[Context]) – optionally the context that caused this error. Click will fill in the context automatically in some situations.

Return type

None

exception click.BadParameter(message, ctx=None, param=None, param_hint=None)¶

An exception that formats out a standardized error message for a bad parameter. This is useful when thrown from a callback or type as Click will attach contextual information to it (for instance, which parameter it is).

Changelog

New in version 2.0.

Parameters

param (Optional[Parameter]) – the parameter object that caused this error. This can be left out, and Click will attach this info itself if possible.
param_hint (Optional[str]) – a string that shows up as parameter name. This can be used as alternative to param in cases where custom validation should happen. If it is a string it’s used as such, if it’s a list then each item is quoted and separated.
message (str) –
ctx (Optional[Context]) –

Return type

None

exception click.FileError(filename, hint=None)¶

Raised if a file cannot be opened.

Parameters

filename (str) –
hint (Optional[str]) –

Return type

None

exception click.NoSuchOption(option_name, message=None, possibilities=None, ctx=None)¶

Raised if click attempted to handle an option that does not exist.

Changelog

New in version 4.0.

Parameters

option_name (str) –
message (Optional[str]) –
possibilities (Optional[Sequence[str]]) –
ctx (Optional[Context]) –

Return type

None

exception click.BadOptionUsage(option_name, message, ctx=None)¶

Raised if an option is generally supplied but the use of the option was incorrect. This is for instance raised if the number of arguments for an option is not correct.

Changelog

New in version 4.0.

Parameters

option_name (str) – the name of the option being used incorrectly.
message (str) –
ctx (Optional[Context]) –

Return type

None

exception click.BadArgumentUsage(message, ctx=None)¶

Raised if an argument is generally supplied but the use of the argument was incorrect. This is for instance raised if the number of values for an argument is not correct.

Changelog

New in version 6.0.

Parameters

message (str) –
ctx (Optional[Context]) –

Return type

None

Formatting¶

class click.HelpFormatter(indent_increment=2, width=None, max_width=None)¶

This class helps with formatting text-based help pages. It’s usually just needed for very special internal cases, but it’s also exposed so that developers can write their own fancy outputs.

At present, it always writes into memory.

Parameters

indent_increment (int) – the additional increment for each level.
width (Optional[int]) – the width for the text. This defaults to the terminal width clamped to a maximum of 78.
max_width (Optional[int]) –

Return type

None

dedent()¶

Decreases the indentation.

Return type: None

getvalue()¶

Returns the buffer contents.

Return type: str

indent()¶

Increases the indentation.

Return type: None

indentation()¶

A context manager that increases the indentation.

Return type: Iterator[None]

section(name)¶

Helpful context manager that writes a paragraph, a heading, and the indents.

Parameters: name (str) – the section name that is written as heading.
Return type: Iterator[None]

write(string)¶

Writes a unicode string into the internal buffer.

Parameters: string (str) –
Return type: None

write_dl(rows, col_max=30, col_spacing=2)¶

Writes a definition list into the buffer. This is how options and commands are usually formatted.

Parameters

rows (Sequence[Tuple[str, str]]) – a list of two item tuples for the terms and values.
col_max (int) – the maximum width of the first column.
col_spacing (int) – the number of spaces between the first and second column.

Return type

None

write_heading(heading)¶

Writes a heading into the buffer.

Parameters: heading (str) –
Return type: None

write_paragraph()¶

Writes a paragraph into the buffer.

Return type: None

write_text(text)¶

Writes re-indented text into the buffer. This rewraps and preserves paragraphs.

Parameters: text (str) –
Return type: None

write_usage(prog, args='', prefix=None)¶

Writes a usage line into the buffer.

Parameters

prog (str) – the program name.
args (str) – whitespace separated list of arguments.
prefix (Optional[str]) – The prefix for the first line. Defaults to "Usage: ".

Return type

None

click.wrap_text(text, width=78, initial_indent='', subsequent_indent='', preserve_paragraphs=False)¶

A helper function that intelligently wraps text. By default, it assumes that it operates on a single paragraph of text but if the preserve_paragraphs parameter is provided it will intelligently handle paragraphs (defined by two empty lines).

If paragraphs are handled, a paragraph can be prefixed with an empty line containing the \b character (\x08) to indicate that no rewrapping should happen in that block.

Parameters

text (str) – the text that should be rewrapped.
width (int) – the maximum width for the text.
initial_indent (str) – the initial indent that should be placed on the first line as a string.
subsequent_indent (str) – the indent string that should be placed on each consecutive line.
preserve_paragraphs (bool) – if this flag is set then the wrapping will intelligently handle paragraphs.

Return type