Django uses request and response objects to pass state through the system.
When a page is requested, Django creates an HttpRequest object that
contains metadata about the request. Then Django loads the appropriate view,
passing the HttpRequest as the first argument to the view function.
Each view is responsible for returning an HttpResponse object.
This document explains the APIs for HttpRequest and
HttpResponse objects, which are defined in the django.http
module.
HttpRequest objects¶All attributes should be considered read-only, unless stated otherwise.
A string representing the scheme of the request (http or https
usually).
The raw HTTP request body as a bytestring. This is useful for processing
data in different ways than conventional HTML forms: binary images,
XML payload etc. For processing conventional form data, use
HttpRequest.POST.
You can also read from an HttpRequest using a file-like interface with
HttpRequest.read() or HttpRequest.readline(). Accessing
the body attribute after reading the request with either of these I/O
stream methods will produce a RawPostDataException.
A string representing the full path to the requested page, not including the scheme, domain, or query string.
Example: "/music/bands/the_beatles/"
Under some web server configurations, the portion of the URL after the
host name is split up into a script prefix portion and a path info
portion. The path_info attribute always contains the path info portion
of the path, no matter what web server is being used. Using this instead
of path can make your code easier to move between
test and deployment servers.
For example, if the WSGIScriptAlias for your application is set to
"/minfo", then path might be "/minfo/music/bands/the_beatles/"
and path_info would be "/music/bands/the_beatles/".
A string representing the HTTP method used in the request. This is guaranteed to be uppercase. For example:
if request.method == "GET":
do_something()
elif request.method == "POST":
do_something_else()
A string representing the current encoding used to decode form submission
data (or None, which means the DEFAULT_CHARSET setting is
used). You can write to this attribute to change the encoding used when
accessing the form data. Any subsequent attribute accesses (such as reading
from GET or POST) will use the new encoding value.
Useful if you know the form data is not in the DEFAULT_CHARSET
encoding.
A string representing the MIME type of the request, parsed from the
CONTENT_TYPE header.
A dictionary of key/value parameters included in the CONTENT_TYPE
header.
A dictionary-like object containing all given HTTP GET parameters. See the
QueryDict documentation below.
A dictionary-like object containing all given HTTP POST parameters,
providing that the request contains form data. See the
QueryDict documentation below. If you need to access raw or
non-form data posted in the request, access this through the
HttpRequest.body attribute instead.
It’s possible that a request can come in via POST with an empty POST
dictionary – if, say, a form is requested via the POST HTTP method but
does not include form data. Therefore, you shouldn’t use if request.POST
to check for use of the POST method; instead, use if request.method ==
"POST" (see HttpRequest.method).
POST does not include file-upload information. See FILES.
A dictionary containing all cookies. Keys and values are strings.
A dictionary-like object containing all uploaded files. Each key in
FILES is the name from the <input type="file" name="">. Each
value in FILES is an UploadedFile.
See Managing files for more information.
FILES will only contain data if the request method was POST and the
<form> that posted to the request had enctype="multipart/form-data".
Otherwise, FILES will be a blank dictionary-like object.
A dictionary containing all available HTTP headers. Available headers depend on the client and server, but here are some examples:
CONTENT_LENGTH – The length of the request body (as a string).
CONTENT_TYPE – The MIME type of the request body.
HTTP_ACCEPT – Acceptable content types for the response.
HTTP_ACCEPT_ENCODING – Acceptable encodings for the response.
HTTP_ACCEPT_LANGUAGE – Acceptable languages for the response.
HTTP_HOST – The HTTP Host header sent by the client.
HTTP_REFERER – The referring page, if any.
HTTP_USER_AGENT – The client’s user-agent string.
QUERY_STRING – The query string, as a single (unparsed) string.
REMOTE_ADDR – The IP address of the client.
REMOTE_HOST – The hostname of the client.
REMOTE_USER – The user authenticated by the web server, if any.
REQUEST_METHOD – A string such as "GET" or "POST".
SERVER_NAME – The hostname of the server.
SERVER_PORT – The port of the server (as a string).
With the exception of CONTENT_LENGTH and CONTENT_TYPE, as given
above, any HTTP headers in the request are converted to META keys by
converting all characters to uppercase, replacing any hyphens with
underscores and adding an HTTP_ prefix to the name. So, for example, a
header called X-Bender would be mapped to the META key
HTTP_X_BENDER.
Note that runserver strips all headers with underscores in the
name, so you won’t see them in META. This prevents header-spoofing
based on ambiguity between underscores and dashes both being normalizing to
underscores in WSGI environment variables. It matches the behavior of
web servers like Nginx and Apache 2.4+.
HttpRequest.headers is a simpler way to access all HTTP-prefixed
headers, plus CONTENT_LENGTH and CONTENT_TYPE.
A case insensitive, dict-like object that provides access to all
HTTP-prefixed headers (plus Content-Length and Content-Type) from
the request.
The name of each header is stylized with title-casing (e.g. User-Agent)
when it’s displayed. You can access headers case-insensitively:
>>> request.headers
{'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6', ...}
>>> "User-Agent" in request.headers
True
>>> "user-agent" in request.headers
True
>>> request.headers["User-Agent"]
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6)
>>> request.headers["user-agent"]
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6)
>>> request.headers.get("User-Agent")
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6)
>>> request.headers.get("user-agent")
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6)
For use in, for example, Django templates, headers can also be looked up using underscores in place of hyphens:
{{ request.headers.user_agent }}
An instance of ResolverMatch representing the
resolved URL. This attribute is only set after URL resolving took place,
which means it’s available in all views but not in middleware which are
executed before URL resolving takes place (you can use it in
process_view() though).
Django doesn’t set these attributes itself but makes use of them if set by your application.
The url template tag will use its value as the current_app
argument to reverse().
This will be used as the root URLconf for the current request, overriding
the ROOT_URLCONF setting. See
How Django processes a request for details.
urlconf can be set to None to revert any changes made by previous
middleware and return to using the ROOT_URLCONF.
This will be used instead of DEFAULT_EXCEPTION_REPORTER_FILTER
for the current request. See Custom error reports for details.
This will be used instead of DEFAULT_EXCEPTION_REPORTER for the
current request. See Custom error reports for details.
Some of the middleware included in Django’s contrib apps set attributes on the
request. If you don’t see the attribute on a request, be sure the appropriate
middleware class is listed in MIDDLEWARE.
From the SessionMiddleware: A
readable and writable, dictionary-like object that represents the current
session.
From the CurrentSiteMiddleware:
An instance of Site or
RequestSite as returned by
get_current_site()
representing the current site.
From the AuthenticationMiddleware:
An instance of AUTH_USER_MODEL representing the currently
logged-in user. If the user isn’t currently logged in, user will be set
to an instance of AnonymousUser. You
can tell them apart with
is_authenticated, like so:
if request.user.is_authenticated:
... # Do something for logged-in users.
else:
... # Do something for anonymous users.
Returns the originating host of the request using information from the
HTTP_X_FORWARDED_HOST (if USE_X_FORWARDED_HOST is enabled)
and HTTP_HOST headers, in that order. If they don’t provide a value,
the method uses a combination of SERVER_NAME and SERVER_PORT as
detailed in PEP 3333.
Example: "127.0.0.1:8000"
Raises django.core.exceptions.DisallowedHost if the host is not in
ALLOWED_HOSTS or the domain name is invalid according to
RFC 1034/1035.
Note
The get_host() method fails when the host is
behind multiple proxies. One solution is to use middleware to rewrite
the proxy headers, as in the following example:
class MultipleProxyMiddleware:
FORWARDED_FOR_FIELDS = [
"HTTP_X_FORWARDED_FOR",
"HTTP_X_FORWARDED_HOST",
"HTTP_X_FORWARDED_SERVER",
]
def __init__(self, get_response):
self.get_response = get_response
def __call__(self, request):
"""
Rewrites the proxy headers so that only the most
recent proxy is used.
"""
for field in self.FORWARDED_FOR_FIELDS:
if field in request.META:
if "," in request.META[field]:
parts = request.META[field].split(",")
request.META[field] = parts[-1].strip()
return self.get_response(request)
This middleware should be positioned before any other middleware that
relies on the value of get_host() – for instance,
CommonMiddleware or
CsrfViewMiddleware.
Returns the originating port of the request using information from the
HTTP_X_FORWARDED_PORT (if USE_X_FORWARDED_PORT is enabled)
and SERVER_PORT META variables, in that order.
Returns the path, plus an appended query string, if applicable.
Example: "/music/bands/the_beatles/?print=true"
Like get_full_path(), but uses path_info instead of
path.
Example: "/minfo/music/bands/the_beatles/?print=true"
Returns the absolute URI form of location. If no location is provided,
the location will be set to request.get_full_path().
If the location is already an absolute URI, it will not be altered. Otherwise the absolute URI is built using the server variables available in this request. For example:
>>> request.build_absolute_uri()
'https://example.com/music/bands/the_beatles/?print=true'
>>> request.build_absolute_uri('/bands/')
'https://example.com/bands/'
>>> request.build_absolute_uri('https://example2.com/bands/')
'https://example2.com/bands/'
Note
Mixing HTTP and HTTPS on the same site is discouraged, therefore
build_absolute_uri() will always generate an
absolute URI with the same scheme the current request has. If you need
to redirect users to HTTPS, it’s best to let your web server redirect
all HTTP traffic to HTTPS.
Returns a cookie value for a signed cookie, or raises a
django.core.signing.BadSignature exception if the signature is
no longer valid. If you provide the default argument the exception
will be suppressed and that default value will be returned instead.
The optional salt argument can be used to provide extra protection
against brute force attacks on your secret key. If supplied, the
max_age argument will be checked against the signed timestamp
attached to the cookie value to ensure the cookie is not older than
max_age seconds.
For example:
>>> request.get_signed_cookie("name")
'Tony'
>>> request.get_signed_cookie("name", salt="name-salt")
'Tony' # assuming cookie was set using the same salt
>>> request.get_signed_cookie("nonexistent-cookie")
KeyError: 'nonexistent-cookie'
>>> request.get_signed_cookie("nonexistent-cookie", False)
False
>>> request.get_signed_cookie("cookie-that-was-tampered-with")
BadSignature: ...
>>> request.get_signed_cookie("name", max_age=60)
SignatureExpired: Signature age 1677.3839159 > 60 seconds
>>> request.get_signed_cookie("name", False, max_age=60)
False
See cryptographic signing for more information.
Returns True if the request is secure; that is, if it was made with
HTTPS.
Returns True if the request Accept header matches the mime_type
argument:
>>> request.accepts("text/html")
True
Most browsers send Accept: */* by default, so this would return
True for all content types. Setting an explicit Accept header in
API requests can be useful for returning a different content type for those
consumers only. See Content negotiation example of using
accepts() to return different content to API consumers.
If a response varies depending on the content of the Accept header and
you are using some form of caching like Django’s cache middleware, you should decorate the view with
vary_on_headers('Accept') so that the responses are
properly cached.
Methods implementing a file-like interface for reading from an
HttpRequest instance. This makes it possible to consume an incoming
request in a streaming fashion. A common use-case would be to process a
big XML payload with an iterative parser without constructing a whole
XML tree in memory.
Given this standard interface, an HttpRequest instance can be
passed directly to an XML parser such as
ElementTree:
import xml.etree.ElementTree as ET
for element in ET.iterparse(request):
process(element)
QueryDict objects¶In an HttpRequest object, the GET and
POST attributes are instances of django.http.QueryDict,
a dictionary-like class customized to deal with multiple values for the same
key. This is necessary because some HTML form elements, notably
<select multiple>, pass multiple values for the same key.
The QueryDicts at request.POST and request.GET will be immutable
when accessed in a normal request/response cycle. To get a mutable version you
need to use QueryDict.copy().
QueryDict implements all the standard dictionary methods because it’s
a subclass of dictionary. Exceptions are outlined here:
Instantiates a QueryDict object based on query_string.
>>> QueryDict('a=1&a=2&c=3')
<QueryDict: {'a': ['1', '2'], 'c': ['3']}>
If query_string is not passed in, the resulting QueryDict will be
empty (it will have no keys or values).
Most QueryDicts you encounter, and in particular those at
request.POST and request.GET, will be immutable. If you are
instantiating one yourself, you can make it mutable by passing
mutable=True to its __init__().
Strings for setting both keys and values will be converted from encoding
to str. If encoding is not set, it defaults to
DEFAULT_CHARSET.
Creates a new QueryDict with keys from iterable and each value
equal to value. For example:
>>> QueryDict.fromkeys(["a", "a", "b"], value="val")
<QueryDict: {'a': ['val', 'val'], 'b': ['val']}>
Returns the value for the given key. If the key has more than one value,
it returns the last value. Raises
django.utils.datastructures.MultiValueDictKeyError if the key does not
exist. (This is a subclass of Python’s standard KeyError, so you can
stick to catching KeyError.)
Sets the given key to [value] (a list whose single element is
value). Note that this, as other dictionary functions that have side
effects, can only be called on a mutable QueryDict (such as one that
was created via QueryDict.copy()).
Returns True if the given key is set. This lets you do, e.g., if "foo"
in request.GET.
Uses the same logic as __getitem__(), with a hook for returning a
default value if the key doesn’t exist.
Like dict.setdefault(), except it uses __setitem__() internally.
Takes either a QueryDict or a dictionary. Like dict.update(),
except it appends to the current dictionary items rather than replacing
them. For example:
>>> q = QueryDict("a=1", mutable=True)
>>> q.update({"a": "2"})
>>> q.getlist("a")
['1', '2']
>>> q["a"] # returns the last
'2'
Like dict.items(), except this uses the same last-value logic as
__getitem__() and returns an iterator object instead of a view object.
For example:
>>> q = QueryDict("a=1&a=2&a=3")
>>> list(q.items())
[('a', '3')]
Like dict.values(), except this uses the same last-value logic as
__getitem__() and returns an iterator instead of a view object. For
example:
>>> q = QueryDict("a=1&a=2&a=3")
>>> list(q.values())
['3']
In addition, QueryDict has the following methods:
Returns a copy of the object using copy.deepcopy(). This copy will
be mutable even if the original was not.
Returns a list of the data with the requested key. Returns an empty list if
the key doesn’t exist and default is None. It’s guaranteed to
return a list unless the default value provided isn’t a list.
Sets the given key to list_ (unlike __setitem__()).
Appends an item to the internal list associated with key.
Like setdefault(), except it takes a list of values instead of a
single value.
Like items(), except it includes all values, as a list, for each
member of the dictionary. For example:
>>> q = QueryDict("a=1&a=2&a=3")
>>> q.lists()
[('a', ['1', '2', '3'])]
Returns a list of values for the given key and removes them from the
dictionary. Raises KeyError if the key does not exist. For example:
>>> q = QueryDict("a=1&a=2&a=3", mutable=True)
>>> q.pop("a")
['1', '2', '3']
Removes an arbitrary member of the dictionary (since there’s no concept
of ordering), and returns a two value tuple containing the key and a list
of all values for the key. Raises KeyError when called on an empty
dictionary. For example:
>>> q = QueryDict("a=1&a=2&a=3", mutable=True)
>>> q.popitem()
('a', ['1', '2', '3'])
Returns a dict representation of QueryDict. For every (key, list)
pair in QueryDict, dict will have (key, item), where item is one
element of the list, using the same logic as QueryDict.__getitem__():
>>> q = QueryDict("a=1&a=3&a=5")
>>> q.dict()
{'a': '5'}
Returns a string of the data in query string format. For example:
>>> q = QueryDict("a=2&b=3&b=5")
>>> q.urlencode()
'a=2&b=3&b=5'
Use the safe parameter to pass characters which don’t require encoding.
For example:
>>> q = QueryDict(mutable=True)
>>> q["next"] = "/a&b/"
>>> q.urlencode(safe="/")
'next=/a%26b/'
HttpResponse objects¶In contrast to HttpRequest objects, which are created automatically by
Django, HttpResponse objects are your responsibility. Each view you
write is responsible for instantiating, populating, and returning an
HttpResponse.
The HttpResponse class lives in the django.http module.
Typical usage is to pass the contents of the page, as a string, bytestring,
or memoryview, to the HttpResponse constructor:
>>> from django.http import HttpResponse
>>> response = HttpResponse("Here's the text of the web page.")
>>> response = HttpResponse("Text only, please.", content_type="text/plain")
>>> response = HttpResponse(b"Bytestrings are also accepted.")
>>> response = HttpResponse(memoryview(b"Memoryview as well."))
But if you want to add content incrementally, you can use response as a
file-like object:
>>> response = HttpResponse()
>>> response.write("<p>Here's the text of the web page.</p>")
>>> response.write("<p>Here's another paragraph.</p>")
Finally, you can pass HttpResponse an iterator rather than strings.
HttpResponse will consume the iterator immediately, store its content as a
string, and discard it. Objects with a close() method such as files and
generators are immediately closed.
If you need the response to be streamed from the iterator to the client, you
must use the StreamingHttpResponse class instead.
To set or remove a header field in your response, use
HttpResponse.headers:
>>> response = HttpResponse()
>>> response.headers["Age"] = 120
>>> del response.headers["Age"]
You can also manipulate headers by treating your response like a dictionary:
>>> response = HttpResponse()
>>> response["Age"] = 120
>>> del response["Age"]
This proxies to HttpResponse.headers, and is the original interface offered
by HttpResponse.
When using this interface, unlike a dictionary, del doesn’t raise
KeyError if the header field doesn’t exist.
You can also set headers on instantiation:
>>> response = HttpResponse(headers={"Age": 120})
For setting the Cache-Control and Vary header fields, it is recommended
to use the patch_cache_control() and
patch_vary_headers() methods from
django.utils.cache, since these fields can have multiple, comma-separated
values. The “patch” methods ensure that other values, e.g. added by a
middleware, are not removed.
HTTP header fields cannot contain newlines. An attempt to set a header field
containing a newline character (CR or LF) will raise BadHeaderError
To tell the browser to treat the response as a file attachment, set the
Content-Type and Content-Disposition headers. For example, this is how
you might return a Microsoft Excel spreadsheet:
>>> response = HttpResponse(
... my_data,
... headers={
... "Content-Type": "application/vnd.ms-excel",
... "Content-Disposition": 'attachment; filename="foo.xls"',
... },
... )
There’s nothing Django-specific about the Content-Disposition header, but
it’s easy to forget the syntax, so we’ve included it here.
A bytestring representing the content, encoded from a string if necessary.
A http.cookies.SimpleCookie object holding the cookies included
in the response.
A case insensitive, dict-like object that provides an interface to all
HTTP headers on the response, except a Set-Cookie header. See
Setting header fields and HttpResponse.cookies.
A string denoting the charset in which the response will be encoded. If not
given at HttpResponse instantiation time, it will be extracted from
content_type and if that is unsuccessful, the
DEFAULT_CHARSET setting will be used.
The HTTP status code for the response.
Unless reason_phrase is explicitly set, modifying the value of
status_code outside the constructor will also modify the value of
reason_phrase.
The HTTP reason phrase for the response. It uses the HTTP standard’s default reason phrases.
Unless explicitly set, reason_phrase is determined by the value of
status_code.
This is always False.
This attribute exists so middleware can treat streaming responses differently from regular responses.
True if the response has been closed.
Instantiates an HttpResponse object with the given page content,
content type, and headers.
content is most commonly an iterator, bytestring, memoryview,
or string. Other types will be converted to a bytestring by encoding their
string representation. Iterators should return strings or bytestrings and
those will be joined together to form the content of the response.
content_type is the MIME type optionally completed by a character set
encoding and is used to fill the HTTP Content-Type header. If not
specified, it is formed by 'text/html' and the
DEFAULT_CHARSET settings, by default:
"text/html; charset=utf-8".
status is the HTTP status code for the
response. You can use Python’s http.HTTPStatus for meaningful
aliases, such as HTTPStatus.NO_CONTENT.
reason is the HTTP response phrase. If not provided, a default phrase
will be used.
charset is the charset in which the response will be encoded. If not
given it will be extracted from content_type, and if that
is unsuccessful, the DEFAULT_CHARSET setting will be used.
headers is a dict of HTTP headers for the response.
Sets the given header name to the given value. Both header and
value should be strings.
Deletes the header with the given name. Fails silently if the header doesn’t exist. Case-insensitive.
Returns the value for the given header name. Case-insensitive.
Returns the value for the given header, or an alternate if the header
doesn’t exist.
Returns True or False based on a case-insensitive check for a
header with the given name.
Acts like dict.items() for HTTP headers on the response.
Sets a header unless it has already been set.
Sets a cookie. The parameters are the same as in the
Morsel cookie object in the Python standard library.
max_age should be a timedelta object, an integer
number of seconds, or None (default) if the cookie should last only
as long as the client’s browser session. If expires is not specified,
it will be calculated.
Support for timedelta objects was added.
expires should either be a string in the format
"Wdy, DD-Mon-YY HH:MM:SS GMT" or a datetime.datetime object
in UTC. If expires is a datetime object, the max_age
will be calculated.
Use domain if you want to set a cross-domain cookie. For example,
domain="example.com" will set a cookie that is readable by the
domains www.example.com, blog.example.com, etc. Otherwise, a cookie will
only be readable by the domain that set it.
Use secure=True if you want the cookie to be only sent to the server
when a request is made with the https scheme.
Use httponly=True if you want to prevent client-side
JavaScript from having access to the cookie.
HttpOnly is a flag included in a Set-Cookie HTTP response header. It’s part of the RFC 6265 standard for cookies and can be a useful way to mitigate the risk of a client-side script accessing the protected cookie data.
Use samesite='Strict' or samesite='Lax' to tell the browser not
to send this cookie when performing a cross-origin request. SameSite
isn’t supported by all browsers, so it’s not a replacement for Django’s
CSRF protection, but rather a defense in depth measure.
Use samesite='None' (string) to explicitly state that this cookie is
sent with all same-site and cross-site requests.
Warning
RFC 6265 states that user agents should support cookies of at least 4096 bytes. For many browsers this is also the maximum size. Django will not raise an exception if there’s an attempt to store a cookie of more than 4096 bytes, but many browsers will not set the cookie correctly.
Like set_cookie(), but
cryptographic signing the cookie before setting
it. Use in conjunction with HttpRequest.get_signed_cookie().
You can use the optional salt argument for added key strength, but
you will need to remember to pass it to the corresponding
HttpRequest.get_signed_cookie() call.
Deletes the cookie with the given key. Fails silently if the key doesn’t exist.
Due to the way cookies work, path and domain should be the same
values you used in set_cookie() – otherwise the cookie may not be
deleted.
This method is called at the end of the request directly by the WSGI server.
This method makes an HttpResponse instance a file-like object.
This method makes an HttpResponse instance a file-like object.
This method makes an HttpResponse instance a file-like object.
Returns the value of HttpResponse.content. This method makes
an HttpResponse instance a stream-like object.
Always False. This method makes an HttpResponse instance a
stream-like object.
Always False. This method makes an HttpResponse instance a
stream-like object.
Always True. This method makes an HttpResponse instance a
stream-like object.
Writes a list of lines to the response. Line separators are not added. This
method makes an HttpResponse instance a stream-like object.
HttpResponse subclasses¶Django includes a number of HttpResponse subclasses that handle different
types of HTTP responses. Like HttpResponse, these subclasses live in
django.http.
The first argument to the constructor is required – the path to redirect
to. This can be a fully qualified URL
(e.g. 'https://www.yahoo.com/search/'), an absolute path with no domain
(e.g. '/search/'), or even a relative path (e.g. 'search/'). In that
last case, the client browser will reconstruct the full URL itself
according to the current path. See HttpResponse for other optional
constructor arguments. Note that this returns an HTTP status code 302.
This read-only attribute represents the URL the response will redirect
to (equivalent to the Location response header).
Like HttpResponseRedirect, but it returns a permanent redirect
(HTTP status code 301) instead of a “found” redirect (status code 302).
The constructor doesn’t take any arguments and no content should be added to this response. Use this to designate that a page hasn’t been modified since the user’s last request (status code 304).
Acts just like HttpResponse but uses a 400 status code.
Acts just like HttpResponse but uses a 404 status code.
Acts just like HttpResponse but uses a 403 status code.
Like HttpResponse, but uses a 405 status code. The first argument
to the constructor is required: a list of permitted methods (e.g.
['GET', 'POST']).
Acts just like HttpResponse but uses a 410 status code.
Acts just like HttpResponse but uses a 500 status code.
Note
If a custom subclass of HttpResponse implements a render
method, Django will treat it as emulating a
SimpleTemplateResponse, and the
render method must itself return a valid response object.
If you find yourself needing a response class that Django doesn’t provide, you
can create it with the help of http.HTTPStatus. For example:
from http import HTTPStatus
from django.http import HttpResponse
class HttpResponseNoContent(HttpResponse):
status_code = HTTPStatus.NO_CONTENT
JsonResponse objects¶An HttpResponse subclass that helps to create a JSON-encoded
response. It inherits most behavior from its superclass with a couple
differences:
Its default Content-Type header is set to application/json.
The first parameter, data, should be a dict instance. If the
safe parameter is set to False (see below) it can be any
JSON-serializable object.
The encoder, which defaults to
django.core.serializers.json.DjangoJSONEncoder, will be used to
serialize the data. See JSON serialization for more details about this serializer.
The safe boolean parameter defaults to True. If it’s set to
False, any object can be passed for serialization (otherwise only
dict instances are allowed). If safe is True and a non-dict
object is passed as the first argument, a TypeError will be raised.
The json_dumps_params parameter is a dictionary of keyword arguments
to pass to the json.dumps() call used to generate the response.
Typical usage could look like:
>>> from django.http import JsonResponse
>>> response = JsonResponse({"foo": "bar"})
>>> response.content
b'{"foo": "bar"}'
In order to serialize objects other than dict you must set the safe
parameter to False:
>>> response = JsonResponse([1, 2, 3], safe=False)
Without passing safe=False, a TypeError will be raised.
Note that an API based on dict objects is more extensible, flexible, and
makes it easier to maintain forwards compatibility. Therefore, you should avoid
using non-dict objects in JSON-encoded response.
Warning
Before the 5th edition of ECMAScript it was possible to
poison the JavaScript Array constructor. For this reason, Django does
not allow passing non-dict objects to the
JsonResponse constructor by default. However, most
modern browsers implement ECMAScript 5 which removes this attack vector.
Therefore it is possible to disable this security precaution.
If you need to use a different JSON encoder class you can pass the encoder
parameter to the constructor method:
>>> response = JsonResponse(data, encoder=MyJSONEncoder)
StreamingHttpResponse objects¶The StreamingHttpResponse class is used to stream a response from
Django to the browser.
Advanced usage
StreamingHttpResponse is somewhat advanced, in that it is
important to know whether you’ll be serving your application synchronously
under WSGI or asynchronously under ASGI, and adjust your usage
appropriately.
Please read these notes with care.
An example usage of StreamingHttpResponse under WSGI is streaming
content when generating the response would take too long or uses too much
memory. For instance, it’s useful for generating large CSV files.
There are performance considerations when doing this, though. Django, under WSGI, is designed for short-lived requests. Streaming responses will tie a worker process for the entire duration of the response. This may result in poor performance.
Generally speaking, you would perform expensive tasks outside of the request-response cycle, rather than resorting to a streamed response.
When serving under ASGI, however, a StreamingHttpResponse need not
stop other requests from being served whilst waiting for I/O. This opens up
the possibility of long-lived requests for streaming content and implementing
patterns such as long-polling, and server-sent events.
Even under ASGI note, StreamingHttpResponse should only be used in
situations where it is absolutely required that the whole content isn’t
iterated before transferring the data to the client. Because the content can’t
be accessed, many middleware can’t function normally. For example the ETag
and Content-Length headers can’t be generated for streaming responses.
The StreamingHttpResponse is not a subclass of HttpResponse,
because it features a slightly different API. However, it is almost identical,
with the following notable differences:
It should be given an iterator that yields bytestrings, memoryview,
or strings as content. When serving under WSGI, this should be a sync
iterator. When serving under ASGI, then it should be an async iterator.
You cannot access its content, except by iterating the response object itself. This should only occur when the response is returned to the client: you should not iterate the response yourself.
Under WSGI the response will be iterated synchronously. Under ASGI the response will be iterated asynchronously. (This is why the iterator type must match the protocol you’re using.)
To avoid a crash, an incorrect iterator type will be mapped to the correct
type during iteration, and a warning will be raised, but in order to do this
the iterator must be fully-consumed, which defeats the purpose of using a
StreamingHttpResponse at all.
It has no content attribute. Instead, it has a
streaming_content attribute. This can be used
in middleware to wrap the response iterable, but should not be consumed.
You cannot use the file-like object tell() or write() methods.
Doing so will raise an exception.
The HttpResponseBase base class is common between
HttpResponse and StreamingHttpResponse.
Support for asynchronous iteration was added.
An iterator of the response content, bytestring encoded according to
HttpResponse.charset.
The HTTP status code for the response.
Unless reason_phrase is explicitly set, modifying the value of
status_code outside the constructor will also modify the value of
reason_phrase.
The HTTP reason phrase for the response. It uses the HTTP standard’s default reason phrases.
Unless explicitly set, reason_phrase is determined by the value of
status_code.
This is always True.
Boolean indicating whether StreamingHttpResponse.streaming_content
is an asynchronous iterator or not.
This is useful for middleware needing to wrap
StreamingHttpResponse.streaming_content.
FileResponse objects¶FileResponse is a subclass of StreamingHttpResponse
optimized for binary files. It uses wsgi.file_wrapper if provided by the wsgi
server, otherwise it streams the file out in small chunks.
If as_attachment=True, the Content-Disposition header is set to
attachment, which asks the browser to offer the file to the user as a
download. Otherwise, a Content-Disposition header with a value of
inline (the browser default) will be set only if a filename is
available.
If open_file doesn’t have a name or if the name of open_file isn’t
appropriate, provide a custom file name using the filename parameter.
Note that if you pass a file-like object like io.BytesIO, it’s your
task to seek() it before passing it to FileResponse.
The Content-Length header is automatically set when it can be guessed
from the content of open_file.
The Content-Type header is automatically set when it can be guessed
from the filename, or the name of open_file.
FileResponse accepts any file-like object with binary content, for example
a file open in binary mode like so:
>>> from django.http import FileResponse
>>> response = FileResponse(open("myfile.png", "rb"))
The file will be closed automatically, so don’t open it with a context manager.
Use under ASGI
Python’s file API is synchronous. This means that the file must be fully consumed in order to be served under ASGI.
In order to stream a file asynchronously you need to use a third-party package that provides an asynchronous file API, such as aiofiles.
This method is automatically called during the response initialization and
set various headers (Content-Length, Content-Type, and
Content-Disposition) depending on open_file.
HttpResponseBase class¶The HttpResponseBase class is common to all Django responses.
It should not be used to create responses directly, but it can be
useful for type-checking.
Dec 25, 2023