Django2.0手册:Request and response objects



Quick overview¶

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¶

class HttpRequest[source]

Attributes¶

All attributes should be considered read-only, unless stated otherwise.

HttpRequest.scheme

A string representing the scheme of the request (http or https
usually).

HttpRequest.body

The raw HTTP request body as a byte string. 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. See
HttpRequest.read().

HttpRequest.path

A string representing the full path to the requested page, not including
the scheme or domain.

Example: "/music/bands/the_beatles/"

HttpRequest.path_info

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/".

HttpRequest.method

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()
HttpRequest.encoding

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.

HttpRequest.content_type

A string representing the MIME type of the request, parsed from the
CONTENT_TYPE header.

HttpRequest.content_params

A dictionary of key/value parameters included in the CONTENT_TYPE
header.

HttpRequest.GET

A dictionary-like object containing all given HTTP GET parameters. See the
QueryDict documentation below.

HttpRequest.POST

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.

HttpRequest.COOKIES

A dictionary containing all cookies. Keys and values are strings.

HttpRequest.FILES

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.

HttpRequest.META

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.resolver_match

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).

Attributes set by application code¶

Django doesn’t set these attributes itself but makes use of them if set by your
application.

HttpRequest.current_app

The url template tag will use its value as the current_app
argument to reverse().

HttpRequest.urlconf

This will be used as the root URLconf for the current request, overriding
the ROOT_URLCONF setting. See
Django 如何处理一个请求 for details.

urlconf can be set to None to revert any changes made by previous
middleware and return to using the ROOT_URLCONF.

Attributes set by middleware¶

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.

HttpRequest.session

From the SessionMiddleware: A
readable and writable, dictionary-like object that represents the current
session.

HttpRequest.site

From the CurrentSiteMiddleware:
An instance of Site or
RequestSite as returned by
get_current_site()
representing the current site.

HttpRequest.user

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.

Methods¶

HttpRequest.get_host()[source]

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"

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:

from django.utils.deprecation import MiddlewareMixin

class MultipleProxyMiddleware(MiddlewareMixin):
    FORWARDED_FOR_FIELDS = [
        'HTTP_X_FORWARDED_FOR',
        'HTTP_X_FORWARDED_HOST',
        'HTTP_X_FORWARDED_SERVER',
    ]

    def process_request(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()

This middleware should be positioned before any other middleware that
relies on the value of get_host() — for instance,
CommonMiddleware or
CsrfViewMiddleware.

HttpRequest.get_port()[source]

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.

HttpRequest.get_full_path()[source]

Returns the path, plus an appended query string, if applicable.

Example: "/music/bands/the_beatles/?print=true"

HttpRequest.build_absolute_uri(location)[source]

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.

Example: "https://example.com/music/bands/the_beatles/?print=true"

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.

HttpRequest.is_secure()[source]

Returns True if the request is secure; that is, if it was made with
HTTPS.

HttpRequest.is_ajax()[source]

Returns True if the request was made via an XMLHttpRequest, by
checking the HTTP_X_REQUESTED_WITH header for the string
'XMLHttpRequest'. Most modern JavaScript libraries send this header.
If you write your own XMLHttpRequest call (on the browser side), you’ll
have to set this header manually if you want is_ajax() to work.

If a response varies on whether or not it’s requested via AJAX and you are
using some form of caching like Django’s cache middleware, you should decorate the view with
vary_on_headers('X-Requested-With') so that the responses are
properly cached.

HttpRequest.read(size=None)[source]
HttpRequest.readline()[source]
HttpRequest.readlines()[source]
HttpRequest.__iter__()[source]

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¶

class QueryDict[source]

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().

Methods¶

QueryDict implements all the standard dictionary methods because it’s
a subclass of dictionary. Exceptions are outlined here:

QueryDict.__init__(query_string=None, mutable=False, encoding=None)[source]

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.

classmethod QueryDict.fromkeys(iterable, value=”, mutable=False, encoding=None)[source]
New in Django 1.11.

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']}>
QueryDict.__getitem__(key)

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.)

QueryDict.__setitem__(key, value)[source]

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()).

QueryDict.__contains__(key)

Returns True if the given key is set. This lets you do, e.g., if "foo"
in request.GET
.

QueryDict.get(key, default=None)

Uses the same logic as __getitem__(), with a hook for returning a
default value if the key doesn’t exist.

QueryDict.setdefault(key, default=None)[source]

Like dict.setdefault(), except it uses __setitem__() internally.

QueryDict.update(other_dict)

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'
QueryDict.items()

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')]
QueryDict.values()

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:

QueryDict.copy()[source]

Returns a copy of the object using copy.deepcopy(). This copy will
be mutable even if the original was not.

QueryDict.getlist(key, default=None)

Returns a list of the data with the requested key. Returns an empty list if
the key doesn’t exist and a default value wasn’t provided. It’s guaranteed
to return a list unless the default value provided isn’t a list.

QueryDict.setlist(key, list_)[source]

Sets the given key to list_ (unlike __setitem__()).

QueryDict.appendlist(key, item)[source]

Appends an item to the internal list associated with key.

QueryDict.setlistdefault(key, default_list=None)[source]

Like setdefault(), except it takes a list of values instead of a
single value.

QueryDict.lists()

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'])]
QueryDict.pop(key)[source]

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']
QueryDict.popitem()[source]

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'])
QueryDict.dict()

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'}
QueryDict.urlencode(safe=None)[source]

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¶

class HttpResponse[source]

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.

Usage¶

Passing strings

Typical usage is to pass the contents of the page, as a string, 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")

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>")

Passing iterators

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.

Setting header fields

To set or remove a header field in your response, treat it like a dictionary:

>>> response = HttpResponse()
>>> response['Age'] = 120
>>> del response['Age']

Note that unlike a dictionary, del doesn’t raise KeyError if the header
field doesn’t exist.

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

Telling the browser to treat the response as a file attachment

To tell the browser to treat the response as a file attachment, use the
content_type argument and set the Content-Disposition header. For example,
this is how you might return a Microsoft Excel spreadsheet:

>>> response = HttpResponse(my_data, content_type='application/vnd.ms-excel')
>>> response['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.

Attributes¶

HttpResponse.content

A bytestring representing the content, encoded from a string if necessary.

HttpResponse.charset

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.

HttpResponse.status_code

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.

HttpResponse.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.

HttpResponse.streaming

This is always False.

This attribute exists so middleware can treat streaming responses
differently from regular responses.

HttpResponse.closed

True if the response has been closed.

Methods¶

HttpResponse.__init__(content=”, content_type=None, status=200, reason=None, charset=None)[source]

Instantiates an HttpResponse object with the given page content and
content type.

content should be an iterator or a string. If it’s an
iterator, it should return strings, and those strings will be
joined together to form the content of the response. If it is not
an iterator or a string, it will be converted to a string when
accessed.

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 the DEFAULT_CONTENT_TYPE and
DEFAULT_CHARSET settings, by default: “text/html; charset=utf-8“.

status is the HTTP status code for the response.

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.

HttpResponse.__setitem__(header, value)

Sets the given header name to the given value. Both header and
value should be strings.

HttpResponse.__delitem__(header)

Deletes the header with the given name. Fails silently if the header
doesn’t exist. Case-insensitive.

HttpResponse.__getitem__(header)

Returns the value for the given header name. Case-insensitive.

HttpResponse.has_header(header)

Returns True or False based on a case-insensitive check for a
header with the given name.

HttpResponse.setdefault(header, value)

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 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.

  • 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 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 is not part of the RFC 2109 standard for cookies,
    and it isn’t honored consistently by all browsers. However,
    when it is honored, it can be a useful way to mitigate the
    risk of a client-side script from accessing the protected cookie
    data.

Warning

Both RFC 2109 and RFC 6265 state 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.

HttpResponse.write(content)[source]

This method makes an HttpResponse instance a file-like object.

HttpResponse.flush()

This method makes an HttpResponse instance a file-like object.

HttpResponse.tell()[source]

This method makes an HttpResponse instance a file-like object.

HttpResponse.getvalue()[source]

Returns the value of HttpResponse.content. This method makes
an HttpResponse instance a stream-like object.

HttpResponse.readable()

Always False. This method makes an HttpResponse instance a
stream-like object.

HttpResponse.seekable()

Always False. This method makes an HttpResponse instance a
stream-like object.

HttpResponse.writable()[source]

Always True. This method makes an HttpResponse instance a
stream-like object.

HttpResponse.writelines(lines)[source]

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.

class HttpResponseRedirect[source]

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.

url

This read-only attribute represents the URL the response will redirect
to (equivalent to the Location response header).

class HttpResponsePermanentRedirect[source]

Like HttpResponseRedirect, but it returns a permanent redirect
(HTTP status code 301) instead of a “found” redirect (status code 302).

class HttpResponseNotModified[source]

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).

class HttpResponseBadRequest[source]

Acts just like HttpResponse but uses a 400 status code.

class HttpResponseNotFound[source]

Acts just like HttpResponse but uses a 404 status code.

class HttpResponseForbidden[source]

Acts just like HttpResponse but uses a 403 status code.

class HttpResponseNotAllowed[source]

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']).

class HttpResponseGone[source]

Acts just like HttpResponse but uses a 410 status code.

class HttpResponseServerError[source]

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.

JsonResponse objects¶

class JsonResponse(data, encoder=DjangoJSONEncoder, safe=True, json_dumps_params=None, **kwargs)[source]

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.

Usage¶

Typical usage could look like:

>>> from django.http import JsonResponse
>>> response = JsonResponse({'foo': 'bar'})
>>> response.content
b'{"foo": "bar"}'

Serializing non-dictionary objects

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.

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.

Changing the default JSON encoder

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¶

class StreamingHttpResponse[source]

The StreamingHttpResponse class is used to stream a response from
Django to the browser. You might want to do this if generating the response
takes too long or uses too much memory. For instance, it’s useful for
generating large CSV files.

Performance considerations

Django 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 should perform expensive tasks outside of the
request-response cycle, rather than resorting to a streamed response.

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 strings as content.
  • You cannot access its content, except by iterating the response object
    itself. This should only occur when the response is returned to the client.
  • It has no content attribute. Instead, it has a
    streaming_content attribute.
  • You cannot use the file-like object tell() or write() methods.
    Doing so will raise an exception.

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.

Attributes¶

StreamingHttpResponse.streaming_content

An iterator of strings representing the content.

StreamingHttpResponse.status_code

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.

StreamingHttpResponse.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.

StreamingHttpResponse.streaming

This is always True.

FileResponse objects¶

class FileResponse[source]

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.

FileResponse expects 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.