Tidy up the sessions documentation creating links for session methods and crosslinking settings
git-svn-id: http://code.djangoproject.com/svn/django/trunk@16245 bcc190cf-cafb-0310-a4f2-bffc1f526a37
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Chris Beaven
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@ -17,14 +17,15 @@ Sessions are implemented via a piece of :doc:`middleware </ref/middleware>`.
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To enable session functionality, do the following:
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* Edit the ``MIDDLEWARE_CLASSES`` setting and make sure
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``MIDDLEWARE_CLASSES`` contains ``'django.contrib.sessions.middleware.SessionMiddleware'``.
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The default ``settings.py`` created by ``django-admin.py startproject`` has
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``SessionMiddleware`` activated.
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* Edit the :setting:`MIDDLEWARE_CLASSES` setting and make sure
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it contains ``'django.contrib.sessions.middleware.SessionMiddleware'``.
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The default ``settings.py`` created by ``django-admin.py startproject``
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has ``SessionMiddleware`` activated.
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If you don't want to use sessions, you might as well remove the
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``SessionMiddleware`` line from ``MIDDLEWARE_CLASSES`` and ``'django.contrib.sessions'``
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from your ``INSTALLED_APPS``. It'll save you a small bit of overhead.
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``SessionMiddleware`` line from ``MIDDLEWARE_CLASSES`` and
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``'django.contrib.sessions'`` from your :setting:`INSTALLED_APPS`.
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It'll save you a small bit of overhead.
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Configuring the session engine
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==============================
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@ -86,56 +87,62 @@ configuration instructions for the `using database-backed sessions`_.
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Using file-based sessions
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-------------------------
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To use file-based sessions, set the ``SESSION_ENGINE`` setting to
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To use file-based sessions, set the :setting:`SESSION_ENGINE` setting to
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``"django.contrib.sessions.backends.file"``.
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You might also want to set the ``SESSION_FILE_PATH`` setting (which defaults
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to output from ``tempfile.gettempdir()``, most likely ``/tmp``) to control
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where Django stores session files. Be sure to check that your Web server has
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permissions to read and write to this location.
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You might also want to set the :setting:`SESSION_FILE_PATH` setting (which
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defaults to output from ``tempfile.gettempdir()``, most likely ``/tmp``) to
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control where Django stores session files. Be sure to check that your Web
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server has permissions to read and write to this location.
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Using sessions in views
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=======================
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When ``SessionMiddleware`` is activated, each ``HttpRequest`` object -- the
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first argument to any Django view function -- will have a ``session``
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attribute, which is a dictionary-like object. You can read it and write to it.
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When ``SessionMiddleware`` is activated, each :class:`~django.http.HttpRequest`
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object -- the first argument to any Django view function -- will have a
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``session`` attribute, which is a dictionary-like object.
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A session object has the following standard dictionary methods:
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You can read it and write to ``request.session`` at any point in your view.
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You can edit it multiple times.
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* ``__getitem__(key)``
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.. class:: backends.base.SessionBase
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This is the base class for all session objects. It has the following
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standard dictionary methods:
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.. method:: __getitem__(key)
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Example: ``fav_color = request.session['fav_color']``
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* ``__setitem__(key, value)``
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.. method:: __setitem__(key, value)
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Example: ``request.session['fav_color'] = 'blue'``
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* ``__delitem__(key)``
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.. method:: __delitem__(key)
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Example: ``del request.session['fav_color']``. This raises ``KeyError``
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if the given ``key`` isn't already in the session.
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* ``__contains__(key)``
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.. method:: __contains__(key)
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Example: ``'fav_color' in request.session``
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* ``get(key, default=None)``
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.. method:: get(key, default=None)
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Example: ``fav_color = request.session.get('fav_color', 'red')``
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* ``keys()``
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.. method:: keys
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* ``items()``
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.. method:: items
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* ``setdefault()``
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.. method:: setdefault
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* ``clear()``
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.. method:: clear
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It also has these methods:
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It also has these methods:
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* ``flush()``
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.. method:: flush
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Delete the current session data from the session and regenerate the
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session key value that is sent back to the user in the cookie. This is
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@ -143,25 +150,25 @@ It also has these methods:
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accessed again from the user's browser (for example, the
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:func:`django.contrib.auth.logout()` function calls it).
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* ``set_test_cookie()``
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.. method:: set_test_cookie
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Sets a test cookie to determine whether the user's browser supports
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cookies. Due to the way cookies work, you won't be able to test this
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until the user's next page request. See `Setting test cookies`_ below for
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more information.
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* ``test_cookie_worked()``
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.. method:: test_cookie_worked
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Returns either ``True`` or ``False``, depending on whether the user's
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browser accepted the test cookie. Due to the way cookies work, you'll
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have to call ``set_test_cookie()`` on a previous, separate page request.
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See `Setting test cookies`_ below for more information.
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* ``delete_test_cookie()``
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.. method:: delete_test_cookie
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Deletes the test cookie. Use this to clean up after yourself.
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* ``set_expiry(value)``
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.. method:: set_expiry(value)
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Sets the expiration time for the session. You can pass a number of
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different values:
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@ -184,26 +191,23 @@ It also has these methods:
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purposes. Session expiration is computed from the last time the
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session was *modified*.
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* ``get_expiry_age()``
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.. method:: get_expiry_age
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Returns the number of seconds until this session expires. For sessions
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with no custom expiration (or those set to expire at browser close), this
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will equal ``settings.SESSION_COOKIE_AGE``.
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will equal :setting:`SESSION_COOKIE_AGE`.
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* ``get_expiry_date()``
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.. method:: get_expiry_date
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Returns the date this session will expire. For sessions with no custom
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expiration (or those set to expire at browser close), this will equal the
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date ``settings.SESSION_COOKIE_AGE`` seconds from now.
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date :setting:`SESSION_COOKIE_AGE` seconds from now.
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* ``get_expire_at_browser_close()``
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.. method:: get_expire_at_browser_close
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Returns either ``True`` or ``False``, depending on whether the user's
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session cookie will expire when the user's Web browser is closed.
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You can edit ``request.session`` at any point in your view. You can edit it
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multiple times.
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Session object guidelines
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-------------------------
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@ -249,25 +253,29 @@ This simplistic view logs in a "member" of the site::
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pass
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return HttpResponse("You're logged out.")
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The standard ``django.contrib.auth.logout()`` function actually does a bit
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more than this to prevent inadvertent data leakage. It calls
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``request.session.flush()``. We are using this example as a demonstration of
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how to work with session objects, not as a full ``logout()`` implementation.
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The standard :meth:`django.contrib.auth.logout` function actually does a bit
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more than this to prevent inadvertent data leakage. It calls the
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:meth:`~backends.base.SessionBase.flush` method of ``request.session``.
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We are using this example as a demonstration of how to work with session
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objects, not as a full ``logout()`` implementation.
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Setting test cookies
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====================
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As a convenience, Django provides an easy way to test whether the user's
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browser accepts cookies. Just call ``request.session.set_test_cookie()`` in a
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view, and call ``request.session.test_cookie_worked()`` in a subsequent view --
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browser accepts cookies. Just call the
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:meth:`~backends.base.SessionBase.set_test_cookie` method of
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``request.session`` in a view, and call
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:meth:`~backends.base.SessionBase.test_cookie_worked` in a subsequent view --
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not in the same view call.
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This awkward split between ``set_test_cookie()`` and ``test_cookie_worked()``
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is necessary due to the way cookies work. When you set a cookie, you can't
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actually tell whether a browser accepted it until the browser's next request.
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It's good practice to use ``delete_test_cookie()`` to clean up after yourself.
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Do this after you've verified that the test cookie worked.
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It's good practice to use
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:meth:`~backends.base.SessionBase.delete_test_cookie()` to clean up after
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yourself. Do this after you've verified that the test cookie worked.
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Here's a typical usage example::
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@ -346,9 +354,9 @@ the session object::
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request.session.modified = True
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To change this default behavior, set the ``SESSION_SAVE_EVERY_REQUEST`` setting
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to ``True``. If ``SESSION_SAVE_EVERY_REQUEST`` is ``True``, Django will save
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the session to the database on every single request.
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To change this default behavior, set the :setting:`SESSION_SAVE_EVERY_REQUEST`
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setting to ``True``. When set to ``True``, Django will save the session to the
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database on every single request.
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Note that the session cookie is only sent when a session has been created or
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modified. If ``SESSION_SAVE_EVERY_REQUEST`` is ``True``, the session cookie
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@ -361,12 +369,13 @@ Browser-length sessions vs. persistent sessions
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===============================================
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You can control whether the session framework uses browser-length sessions vs.
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persistent sessions with the ``SESSION_EXPIRE_AT_BROWSER_CLOSE`` setting.
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persistent sessions with the :setting:`SESSION_EXPIRE_AT_BROWSER_CLOSE`
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setting.
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By default, ``SESSION_EXPIRE_AT_BROWSER_CLOSE`` is set to ``False``, which
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means session cookies will be stored in users' browsers for as long as
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``SESSION_COOKIE_AGE``. Use this if you don't want people to have to log in
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every time they open a browser.
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:setting:`SESSION_COOKIE_AGE`. Use this if you don't want people to have to
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log in every time they open a browser.
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If ``SESSION_EXPIRE_AT_BROWSER_CLOSE`` is set to ``True``, Django will use
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browser-length cookies -- cookies that expire as soon as the user closes his or
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@ -374,8 +383,8 @@ her browser. Use this if you want people to have to log in every time they open
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a browser.
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This setting is a global default and can be overwritten at a per-session level
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by explicitly calling ``request.session.set_expiry()`` as described above in
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`using sessions in views`_.
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by explicitly calling the :meth:`~backends.base.SessionBase.set_expiry` method
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of ``request.session`` as described above in `using sessions in views`_.
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Clearing the session table
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==========================
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@ -397,7 +406,8 @@ in the past -- but your application may have different requirements.
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Settings
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========
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A few :doc:`Django settings </ref/settings>` give you control over session behavior:
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A few :doc:`Django settings </ref/settings>` give you control over session
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behavior:
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SESSION_ENGINE
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--------------
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