Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
Browse files

Added docs/request_response.txt

git-svn-id: http://code.djangoproject.com/svn/django/trunk@592 bcc190cf-cafb-0310-a4f2-bffc1f526a37
  • Loading branch information...
commit b483f66efefca1029d6ac8b9836f9db844ced05f 1 parent af8b7ff
@adrianholovaty adrianholovaty authored
Showing with 312 additions and 0 deletions.
  1. +312 −0 docs/request_response.txt
View
312 docs/request_response.txt
@@ -0,0 +1,312 @@
+============================
+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.
+
+HttpRequest objects
+===================
+
+Attributes
+----------
+
+All attributes except ``session`` should be considered read-only.
+
+``path``
+ A string representing the full path to the requested page, not including
+ the domain.
+
+ Example: ``"/music/bands/the_beatles/"``
+
+``GET``
+ A dictionary-like object containing all given HTTP GET parameters. See the
+ ``MultiValueDict`` documentation below.
+
+``POST``
+ A dictionary-like object containing all given HTTP POST parameters. See the
+ ``MultiValueDict`` documentation below.
+
+``REQUEST``
+ For convenience, a dictionary-like object that searches ``POST`` first,
+ then ``GET``. Inspired by PHP's ``$_REQUEST``.
+
+ For example, if ``GET = {"name": "john"}`` and ``POST = {"age": '34'}``,
+ ``REQUEST["name"]`` would be ``"john"``, and ``REQUEST["age"]`` would be
+ ``"34"``.
+
+ It's strongly suggested that you use ``GET`` and ``POST`` instead of
+ ``REQUEST``, because the former are more explicit.
+
+``COOKIES``
+ A standard Python dictionary containing all cookies. Keys and values are
+ strings.
+
+``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 a standard Python dictionary with the following three
+ keys:
+
+ * ``filename`` -- The name of the uploaded file, as a Python string.
+ * ``content-type`` -- The content type of the uploaded file.
+ * ``content`` -- The raw content of the uploaded file.
+
+ Note that ``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.
+
+``META``
+ A standard Python dictionary containing all available HTTP headers.
+ Available headers depend on the client and server, but here are some
+ examples:
+
+ * ``CONTENT_LENGTH``
+ * ``CONTENT_TYPE``
+ * ``HTTP_ACCEPT_ENCODING``
+ * ``HTTP_ACCEPT_LANGUAGE``
+ * ``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.
+ * ``REQUEST_METHOD`` -- A string such as ``"GET"`` or ``"POST"``.
+ * ``SERVER_NAME`` -- The hostname of the server.
+ * ``SERVER_PORT`` -- The port of the server.
+
+``user``
+ A ``django.models.auth.users.User`` object representing the currently
+ logged-in user. If the user isn't currently logged in, ``user`` will be set
+ to an instance of ``django.parts.auth.anonymoususers.AnonymousUser``. You
+ can tell them apart with ``is_anonymous()``, like so::
+
+ if request.user.is_anonymous():
+ # Do something for anonymous users.
+ else:
+ # Do something for logged-in users.
+
+``session``
+ A readable-and-writable, dictionary-like object that represents the current
+ session. This is only available if your Django installation has session
+ support activated. See the `session documentation`_ for full details.
+
+ .. _`session documentation`: http://www.djangoproject.com/documentation/sessions/
+
+``raw_post_data``
+ The raw HTTP POST data. This is only useful for advanced processing. Use
+ ``POST`` instead.
+
+Methods
+-------
+
+``get_full_path()``
+ Returns the ``path``, plus an appended query string, if applicable.
+
+ Example: ``"/music/bands/the_beatles/?print=true"``
+
+MultiValueDict objects
+----------------------
+
+In an ``HttpRequest`` object, the ``GET`` and ``POST`` attributes are instances
+of ``django.utils.datastructures.MultiValueDict``. ``MultiValueDict`` is 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.
+
+``MultiValueDict`` implements the following standard dictionary methods:
+
+ * ``__repr__()``
+
+ * ``__getitem__(key)`` -- Returns the value for the given key. If the key
+ has more than one value, ``__getitem__()`` returns the last value.
+
+ * ``__setitem__(key, value)`` -- Sets the given key to ``[value]``
+ (a Python list whose single element is ``value``).
+
+ * ``__len__()``
+
+ * ``get(key, default)`` -- Uses the same logic as ``__getitem__()`` above,
+ with a hook for returning a default value if the key doesn't exist.
+
+ * ``has_key(key)``
+
+ * ``items()``
+
+ * ``keys()``
+
+ * ``update(other_dict)``
+
+In addition, it has the following methods:
+
+ * ``copy()`` -- Returns a copy of the object, using ``copy.deepcopy()``
+ from the Python standard library.
+
+ * ``getlist(key)`` -- Returns the data with the requested key, as a Python
+ list. Returns an empty list if the key doesn't exist.
+
+ * ``setlist(key, list_)`` -- Sets the given key to ``list_`` (unlike
+ ``__setitem__()``).
+
+ * ``appendlist(key, item)`` -- Appends an item to the internal list
+ associated with key.
+
+Examples
+--------
+
+Here's an example HTML form and how Django would treat the input::
+
+ <form action="/foo/bar/" method="post">
+ <input type="text" name="your_name" />
+ <select multiple="multiple" name="bands">
+ <option value="beatles">The Beatles</option>
+ <option value="who">The Who</option>
+ <option value="zombies">The Zombies</option>
+ </select>
+ <input type="submit" />
+ </form>
+
+If the user enters ``"John Smith"`` in the ``your_name`` field and selects both
+"The Beatles" and "The Zombies" in the multiple select box, here's what
+Django's request object would have::
+
+ >>> request.GET
+ {}
+ >>> request.POST
+ {'your_name': ['John Smith'], 'bands': ['beatles', 'zombies']}
+ >>> request.POST['your_name']
+ 'John Smith'
+ >>> request.POST['bands']
+ 'zombies'
+ >>> request.POST.getlist('bands')
+ ['beatles', 'zombies']
+ >>> request.POST.get('your_name', 'Adrian')
+ 'John Smith'
+ >>> request.POST.get('nonexistent_field', 'Nowhere Man')
+ 'Nowhere Man'
+
+Implementation notes
+--------------------
+
+The ``GET``, ``POST``, ``COOKIES``, ``FILES``, ``META``, ``REQUEST``,
+``raw_post_data`` and ``user`` attributes are all lazily loaded. That means
+Django doesn't spend resources calculating the values of those attributes until
+your code requests them.
+
+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 at ``django.utils.httpwrappers.HttpResponse``.
+
+Usage
+-----
+
+Typical usage is to pass the contents of the page, as a string, to the
+``HttpResponse`` constructor::
+
+ >>> response = HttpResponse("Here's the text of the Web page.")
+ >>> response = HttpResponse("Text only, please.", mimetype="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>")
+
+You can add and delete headers using dictionary syntax::
+
+ >>> response = HttpResponse()
+ >>> response['X-DJANGO'] = "It's the best."
+ >>> del response['X-PHP']
+ >>> response['X-DJANGO']
+ "It's the best."
+
+Note that ``del`` doesn't raise ``KeyError`` if the header doesn't exist.
+
+Methods
+-------
+
+``__init__(content='', mimetype=DEFAULT_MIME_TYPE)``
+ Instantiates an ``HttpResponse`` object with the given page content (a
+ string) and MIME type. The ``DEFAULT_MIME_TYPE`` is ``"text/html"``.
+
+``__setitem__(header, value)``
+ Sets the given header name to the given value. Both ``header`` and
+ ``value`` should be strings.
+
+``__delitem__(header)``
+ Deletes the header with the given name. Fails silently if the header
+ doesn't exist. Case-sensitive.
+
+``__getitem__(header)``
+ Returns the value for the given header name. Case-sensitive.
+
+``has_header(header)``
+ Returns ``True`` or ``False`` based on a case-insensitive check for a
+ header with the given name.
+
+``set_cookie(key, value='', max_age=None, path='/', domain=None, secure=None)``
+ Sets a cookie. The parameters are the same as in the `Cookie.Morsel`_
+ 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.
+ * Use ``domain`` if you want to set a cross-domain cookie. For example,
+ ``domain=".lawrence.com"`` will set a cookie that is readable by
+ the domains www.lawrence.com, blogs.lawrence.com and
+ calendars.lawrence.com. Otherwise, a cookie will only be readable by
+ the domain that set it.
+
+ .. _`Cookie.Morsel object`: http://www.python.org/doc/current/lib/morsel-objects.html
+
+``get_content_as_string(encoding)``
+ Returns the content as a Python string, encoding it from a Unicode object
+ if necessary.
+
+``write(content)``
+``flush()``
+``tell()``
+ These methods make an ``HttpResponse`` instance a file-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.utils.httpwrappers``.
+
+``HttpResponseRedirect``
+ The constructor takes a single argument -- the path to redirect to. This
+ can be a fully qualified URL (e.g. ``"http://www.yahoo.com/search/"``) or an
+ absolute URL with no domain (e.g. ``"/search/"``).
+
+``HttpResponseNotModified``
+ The constructor doesn't take any arguments. Use this to designate that a
+ page hasn't been modified since the user's last request.
+
+``HttpResponseNotFound``
+ Acts just like ``HttpResponse`` but uses a 404 status code.
+
+``HttpResponseForbidden``
+ Acts just like ``HttpResponse`` but uses a 403 status code.
+
+``HttpResponseGone``
+ Acts just like ``HttpResponse`` but uses a 410 status code.
+
+``HttpResponseServerError``
+ Acts just like ``HttpResponse`` but uses a 500 status code.
Please sign in to comment.
Something went wrong with that request. Please try again.