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Django 1.11
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Bagaimana menggunakan sesi

Django provides full support for anonymous sessions. The session framework lets you store and retrieve arbitrary data on a per-site-visitor basis. It stores data on the server side and abstracts the sending and receiving of cookies. Cookies contain a session ID -- not the data itself (unless you're using the cookie based backend).

Mengadakan sesi

Sesi diterapkan melalui potongan middleware 1.

Untuk mengadakan fungsi sesi, lakukan berikut:

  • Edit the MIDDLEWARE setting and make sure it contains 'django.contrib.sessions.middleware.SessionMiddleware'. The default settings.py created by django-admin startproject has SessionMiddleware activated.

Jika anda tidak ingin menggunakan sesi, anda mungkin akan memindahkan baris SessionMiddleware dari MIDDLEWARE dan 'django.contrib.sessions' dari INSTALLED_APPS anda. Itu akan menyimpan anda sedikit diatas.

Konfigurasi mesin sesi

By default, Django stores sessions in your database (using the model django.contrib.sessions.models.Session). Though this is convenient, in some setups it's faster to store session data elsewhere, so Django can be configured to store session data on your filesystem or in your cache.

Menggunakan sesi didukung-basisdata

If you want to use a database-backed session, you need to add 'django.contrib.sessions' to your INSTALLED_APPS setting.

Once you have configured your installation, run manage.py migrate to install the single database table that stores session data.

Menggunakan sesi tembolok

For better performance, you may want to use a cache-based session backend.

To store session data using Django's cache system, you'll first need to make sure you've configured your cache; see the cache documentation for details.

Jika anda mempunyai banyak tembolok ditentukan di CACHES,Django akan menggunakan tembolok awalan. Untuk menggunakan tembolok lain, setel SESSION_CACHE_ALIAS ke nama dari tembolok tersebut.

Sekali tembolok anda dikonfigurasi, anda telah mendapatkan dua pilihan untuk bagaimana menyimpan data dalam tembolok:

  • Set SESSION_ENGINE to "django.contrib.sessions.backends.cache" for a simple caching session store. Session data will be stored directly in your cache. However, session data may not be persistent: cached data can be evicted if the cache fills up or if the cache server is restarted.

  • For persistent, cached data, set SESSION_ENGINE to "django.contrib.sessions.backends.cached_db". This uses a write-through cache -- every write to the cache will also be written to the database. Session reads only use the database if the data is not already in the cache.

Both session stores are quite fast, but the simple cache is faster because it disregards persistence. In most cases, the cached_db backend will be fast enough, but if you need that last bit of performance, and are willing to let session data be expunged from time to time, the cache backend is for you.

If you use the cached_db session backend, you also need to follow the configuration instructions for the using database-backed sessions.

Using file-based sessions

To use file-based sessions, set the SESSION_ENGINE setting to "django.contrib.sessions.backends.file".

You might also want to set the SESSION_FILE_PATH setting (which defaults to output from tempfile.gettempdir(), most likely /tmp) to control where Django stores session files. Be sure to check that your Web server has permissions to read and write to this location.

Menggunakan sesi dalam tampilan

When SessionMiddleware is activated, each HttpRequest object -- the first argument to any Django view function -- will have a session attribute, which is a dictionary-like object.

You can read it and write to request.session at any point in your view. You can edit it multiple times.

class backends.base.SessionBase

This is the base class for all session objects. It has the following standard dictionary methods:

__getitem__(key)

Contoh: fav_color = request.session['fav_color']

__setitem__(key, value)

Contoh: request.session['fav_color'] = 'blue'

__delitem__(key)

Example: del request.session['fav_color']. This raises KeyError if the given key isn't already in the session.

__contains__(key)

Contoh: 'fav_color' dalam request.session

get(key, default=None)

Contoh: fav_color = request.session.get('fav_color', 'red')

pop(key, default=__not_given)

Contoh: fav_color = request.session.pop('fav_color', 'blue')

keys()
items()
setdefault()
clear()

Dia juga mempunyai cara ini:

flush()

Deletes the current session data from the session and deletes the session cookie. This is used if you want to ensure that the previous session data can't be accessed again from the user's browser (for example, the django.contrib.auth.logout() function calls it).

Sets a test cookie to determine whether the user's browser supports cookies. Due to the way cookies work, you won't be able to test this until the user's next page request. See Setting test cookies below for more information.

Returns either True or False, depending on whether the user's browser accepted the test cookie. Due to the way cookies work, you'll have to call set_test_cookie() on a previous, separate page request. See Setting test cookies below for more information.

Menghapus kue percobaan. Gunakan ini untuk membersihkan diri anda sendiri.

set_expiry(value)

Setel waktu kadaluarsa untuk sesi. Anda dapat melewatkan sejumlah nilai berbeda:

  • If value is an integer, the session will expire after that many seconds of inactivity. For example, calling request.session.set_expiry(300) would make the session expire in 5 minutes.

  • If value is a datetime or timedelta object, the session will expire at that specific date/time. Note that datetime and timedelta values are only serializable if you are using the PickleSerializer.

  • If value is 0, the user's session cookie will expire when the user's Web browser is closed.

  • If value is None, the session reverts to using the global session expiry policy.

Reading a session is not considered activity for expiration purposes. Session expiration is computed from the last time the session was modified.

get_expiry_age()

Returns the number of seconds until this session expires. For sessions with no custom expiration (or those set to expire at browser close), this will equal SESSION_COOKIE_AGE.

Fungsi ini menerima dua pilihan argumen katakunci:

  • modification: last modification of the session, as a datetime object. Defaults to the current time.

  • expiry: expiry information for the session, as a datetime object, an int (in seconds), or None. Defaults to the value stored in the session by set_expiry(), if there is one, or None.

get_expiry_date()

Returns the date this session will expire. For sessions with no custom expiration (or those set to expire at browser close), this will equal the date SESSION_COOKIE_AGE seconds from now.

Fungsi ini menerima argumen kata kunci sama seperti get_expiry_age().

get_expire_at_browser_close()

Returns either True or False, depending on whether the user's session cookie will expire when the user's Web browser is closed.

clear_expired()

Memindahkan sesi kadaluarsa dari penyimpanan sesi. Metode kelas ini dipanggil oleh clearsessions.

cycle_key()

Creates a new session key while retaining the current session data. django.contrib.auth.login() calls this method to mitigate against session fixation.

Serialisasi sesi

By default, Django serializes session data using JSON. You can use the SESSION_SERIALIZER setting to customize the session serialization format. Even with the caveats described in Tulis serialisasi anda sendiri, we highly recommend sticking with JSON serialization especially if you are using the cookie backend.

For example, here's an attack scenario if you use pickle to serialize session data. If you're using the signed cookie session backend and SECRET_KEY is known by an attacker (there isn't an inherent vulnerability in Django that would cause it to leak), the attacker could insert a string into their session which, when unpickled, executes arbitrary code on the server. The technique for doing so is simple and easily available on the internet. Although the cookie session storage signs the cookie-stored data to prevent tampering, a SECRET_KEY leak immediately escalates to a remote code execution vulnerability.

Bundled serializers

class serializers.JSONSerializer

A wrapper around the JSON serializer from django.core.signing. Can only serialize basic data types.

In addition, as JSON supports only string keys, note that using non-string keys in request.session won't work as expected:

Code
>>> # initial assignment
>>> request.session[0] = 'bar'
>>> # subsequent requests following serialization & deserialization
>>> # of session data
>>> request.session[0]  # KeyError
>>> request.session['0']
'bar'

Similarly, data that can't be encoded in JSON, such as non-UTF8 bytes like '\xd9' (which raises UnicodeDecodeError), can't be stored.

See the Tulis serialisasi anda sendiri section for more details on limitations of JSON serialization.

class serializers.PickleSerializer

Supports arbitrary Python objects, but, as described above, can lead to a remote code execution vulnerability if SECRET_KEY becomes known by an attacker.

Tulis serialisasi anda sendiri

Note that unlike PickleSerializer, the JSONSerializer cannot handle arbitrary Python data types. As is often the case, there is a trade-off between convenience and security. If you wish to store more advanced data types including datetime and Decimal in JSON backed sessions, you will need to write a custom serializer (or convert such values to a JSON serializable object before storing them in request.session). While serializing these values is fairly straightforward (DjangoJSONEncoder may be helpful), writing a decoder that can reliably get back the same thing that you put in is more fragile. For example, you run the risk of returning a datetime that was actually a string that just happened to be in the same format chosen for datetimes).

Your serializer class must implement two methods, dumps(self, obj) and loads(self, data), to serialize and deserialize the dictionary of session data, respectively.

Panduan obyek sesi

  • Use normal Python strings as dictionary keys on request.session. This is more of a convention than a hard-and-fast rule.

  • Kunci dictionary sesi yang dimulai dengan garis bawah adalah dipesan untuk penggunaan dalam oleh Django.

  • Jangan menimpa request.session dengan obyek baru, dan jangan mengakses atau menyetel atributnya. Gunakan itu seperti dictionary Python.

Contoh

Tampilan sederhana ini menyetel sebuah variabel has_commented menjadi True setelah pengguna menempatkan sebuah komentar. Itu tidak membuat pengguna menempatkan komentar lebih dari satu:

Code
def post_comment(request, new_comment):
    if request.session.get('has_commented', False):
        return HttpResponse("You've already commented.")
    c = comments.Comment(comment=new_comment)
    c.save()
    request.session['has_commented'] = True
    return HttpResponse('Thanks for your comment!')

This simplistic view logs in a "member" of the site:

Code
def login(request):
    m = Member.objects.get(username=request.POST['username'])
    if m.password == request.POST['password']:
        request.session['member_id'] = m.id
        return HttpResponse("You're logged in.")
    else:
        return HttpResponse("Your username and password didn't match.")

...Dan satu ini mencatat anggota keluar, menurut pada login() diatas:

Code
def logout(request):
    try:
        del request.session['member_id']
    except KeyError:
        pass
    return HttpResponse("You're logged out.")

The standard django.contrib.auth.logout() function actually does a bit more than this to prevent inadvertent data leakage. It calls the flush() method of request.session. We are using this example as a demonstration of how to work with session objects, not as a full logout() implementation.

Mengatur kue percobaan

As a convenience, Django provides an easy way to test whether the user's browser accepts cookies. Just call the set_test_cookie() method of request.session in a view, and call test_cookie_worked() in a subsequent view -- not in the same view call.

This awkward split between set_test_cookie() and test_cookie_worked() is necessary due to the way cookies work. When you set a cookie, you can't actually tell whether a browser accepted it until the browser's next request.

It's good practice to use delete_test_cookie() to clean up after yourself. Do this after you've verified that the test cookie worked.

Ini adalah contoh penggunaan khas:

Code
from django.http import HttpResponse
from django.shortcuts import render

def login(request):
    if request.method == 'POST':
        if request.session.test_cookie_worked():
            request.session.delete_test_cookie()
            return HttpResponse("You're logged in.")
        else:
            return HttpResponse("Please enable cookies and try again.")
    request.session.set_test_cookie()
    return render(request, 'foo/login_form.html')

Using sessions out of views

Sebuah API tersedia untuk merubah data sesi diluar tampilan:

Code
>>> from django.contrib.sessions.backends.db import SessionStore
>>> s = SessionStore()
>>> # stored as seconds since epoch since datetimes are not serializable in JSON.
>>> s['last_login'] = 1376587691
>>> s.create()
>>> s.session_key
'2b1189a188b44ad18c35e113ac6ceead'
>>> s = SessionStore(session_key='2b1189a188b44ad18c35e113ac6ceead')
>>> s['last_login']
1376587691

SessionStore.create() is designed to create a new session (i.e. one not loaded from the session store and with session_key=None). save() is designed to save an existing session (i.e. one loaded from the session store). Calling save() on a new session may also work but has a small chance of generating a session_key that collides with an existing one. create() calls save() and loops until an unused session_key is generated.

If you're using the django.contrib.sessions.backends.db backend, each session is just a normal Django model. The Session model is defined in django/contrib/sessions/models.py. Because it's a normal model, you can access sessions using the normal Django database API:

Code
>>> from django.contrib.sessions.models import Session
>>> s = Session.objects.get(pk='2b1189a188b44ad18c35e113ac6ceead')
>>> s.expire_date
datetime.datetime(2005, 8, 20, 13, 35, 12)

Note that you'll need to call get_decoded() to get the session dictionary. This is necessary because the dictionary is stored in an encoded format:

Code
>>> s.session_data
'KGRwMQpTJ19hdXRoX3VzZXJfaWQnCnAyCkkxCnMuMTExY2ZjODI2Yj...'
>>> s.get_decoded()
{'user_id': 42}

Ketika sesi disimpan

By default, Django only saves to the session database when the session has been modified -- that is if any of its dictionary values have been assigned or deleted:

Code
# Session is modified.
request.session['foo'] = 'bar'

# Session is modified.
del request.session['foo']

# Session is modified.
request.session['foo'] = {}

# Gotcha: Session is NOT modified, because this alters
# request.session['foo'] instead of request.session.
request.session['foo']['bar'] = 'baz'

In the last case of the above example, we can tell the session object explicitly that it has been modified by setting the modified attribute on the session object:

Code
request.session.modified = True

To change this default behavior, set the SESSION_SAVE_EVERY_REQUEST setting to True. When set to True, Django will save the session to the database on every single request.

Note that the session cookie is only sent when a session has been created or modified. If SESSION_SAVE_EVERY_REQUEST is True, the session cookie will be sent on every request.

Similarly, the expires part of a session cookie is updated each time the session cookie is sent.

Sesi tidak disimpan jika kode keadaan tanggapan adalah 500.

Browser-length sessions vs. persistent sessions

You can control whether the session framework uses browser-length sessions vs. persistent sessions with the SESSION_EXPIRE_AT_BROWSER_CLOSE setting.

By default, SESSION_EXPIRE_AT_BROWSER_CLOSE is set to False, which means session cookies will be stored in users' browsers for as long as SESSION_COOKIE_AGE. Use this if you don't want people to have to log in every time they open a browser.

If SESSION_EXPIRE_AT_BROWSER_CLOSE is set to True, Django will use browser-length cookies -- cookies that expire as soon as the user closes their browser. Use this if you want people to have to log in every time they open a browser.

This setting is a global default and can be overwritten at a per-session level by explicitly calling the set_expiry() method of request.session as described above in using sessions in views.

Membersihkan toko sesi

As users create new sessions on your website, session data can accumulate in your session store. If you're using the database backend, the django_session database table will grow. If you're using the file backend, your temporary directory will contain an increasing number of files.

To understand this problem, consider what happens with the database backend. When a user logs in, Django adds a row to the django_session database table. Django updates this row each time the session data changes. If the user logs out manually, Django deletes the row. But if the user does not log out, the row never gets deleted. A similar process happens with the file backend.

Django does not provide automatic purging of expired sessions. Therefore, it's your job to purge expired sessions on a regular basis. Django provides a clean-up management command for this purpose: clearsessions. It's recommended to call this command on a regular basis, for example as a daily cron job.

Note that the cache backend isn't vulnerable to this problem, because caches automatically delete stale data. Neither is the cookie backend, because the session data is stored by the users' browsers.

Pengaturan

Sedikit Django settings 1 memberikan anda mengendalikan terhadap perilaku sesi:

Keamanan sesi

Subdomains within a site are able to set cookies on the client for the whole domain. This makes session fixation possible if cookies are permitted from subdomains not controlled by trusted users.

For example, an attacker could log into good.example.com and get a valid session for their account. If the attacker has control over bad.example.com, they can use it to send their session key to you since a subdomain is permitted to set cookies on *.example.com. When you visit good.example.com, you'll be logged in as the attacker and might inadvertently enter your sensitive personal data (e.g. credit card info) into the attackers account.

Another possible attack would be if good.example.com sets its SESSION_COOKIE_DOMAIN to ".example.com" which would cause session cookies from that site to be sent to bad.example.com.

Rincian teknik

  • The session dictionary accepts any json serializable value when using JSONSerializer or any picklable Python object when using PickleSerializer. See the pickle module for more information.

  • Data sesi disimpan dalam tabel basisdata bernama django_session .

  • Django hanya mengirim kue jika itu dibutuhkan. Jika anda tidak menyetel data sesi, itu tidak akan mengirim kue sesi.

Obyek SessionStore

Ketika bekerja dengan sesi di dalam, Django menggunakan sebuah sesi menyimpan obyek dari mesin sesi sesuai. Secara kebiasaan, sesi menyimpan kelas obyek dinamai SessionStore dan ditempatkan dalam model dirancang oleh SESSION_ENGINE.

All SessionStore classes available in Django inherit from SessionBase and implement data manipulation methods, namely:

In order to build a custom session engine or to customize an existing one, you may create a new class inheriting from SessionBase or any other existing SessionStore class.

Extending most of the session engines is quite straightforward, but doing so with database-backed session engines generally requires some extra effort (see the next section for details).

Memperpanjang mesin sesi didukung-basisdata

Creating a custom database-backed session engine built upon those included in Django (namely db and cached_db) may be done by inheriting AbstractBaseSession and either SessionStore class.

AbstractBaseSession and BaseSessionManager are importable from django.contrib.sessions.base_session so that they can be imported without including django.contrib.sessions in INSTALLED_APPS.

class base_session.AbstractBaseSession

The abstract base session model.

session_key

Primary key. The field itself may contain up to 40 characters. The current implementation generates a 32-character string (a random sequence of digits and lowercase ASCII letters).

session_data

String mengandung sebyag dictionary sesi disandikan dan diserialisasikan.

expire_date

Menunjuk datetime ketika sesi kadaluarsa.

Sesi kadaluarsa tidak tersedia ke seorang pengguna, bagaimanapun, mereka masih disimpan dalam basisdata sampai perintah pengelolaan clearsessions berjalan.

classmethod get_session_store_class()

Mengembalikan kelas penyimpanan sesi untuk digunakan dengan model sesi ini.

get_decoded()

Mengembalikan data sesi diterjemahkan.

Penterjemahan dilakukan oleh kelas penyimpanan sesi.

Anda dapat juga menyesuaikan pengelola model dengan mensubkelaskan BaseSessionManager:

class base_session.BaseSessionManager
encode(session_dict)

Mengembalikan dictionary sesi diberikan terserialisasi dan disandikan sebagai sebuah string.

Penyandian dialkukan oleh kelas penyimpanan sesi diikat ke kelas model.

save(session_key, session_dict, expire_date)

Saves session data for a provided session key, or deletes the session in case the data is empty.

Customization of SessionStore classes is achieved by overriding methods and properties described below:

class backends.db.SessionStore

Menerapkan penyimpanan sesi backend-basisdata.

classmethod get_model_class()

Kesampingkan metode ini untuk mengembalikan sebuah penyesuaian model sesi jika anda butuh satu.

create_model_instance(data)

Mengembalikan sebuah instance baru dari obyek model sesi, yang mewakili keadaan sesi saat ini.

Kesampingkan metode ini menyediakan kemampuan merubah data model sesi sebelum itu disimpan ke basisdata.

class backends.cached_db.SessionStore

Implements cached database-backed session store.

cache_key_prefix

Sebuah awalan ditambahkan ke kunci sesi untuk membangun string kunci cache.

Contoh

The example below shows a custom database-backed session engine that includes an additional database column to store an account ID (thus providing an option to query the database for all active sessions for an account):

Code
from django.contrib.sessions.backends.db import SessionStore as DBStore
from django.contrib.sessions.base_session import AbstractBaseSession
from django.db import models

class CustomSession(AbstractBaseSession):
    account_id = models.IntegerField(null=True, db_index=True)

    @classmethod
    def get_session_store_class(cls):
        return SessionStore

class SessionStore(DBStore):
    @classmethod
    def get_model_class(cls):
        return CustomSession

    def create_model_instance(self, data):
        obj = super(SessionStore, self).create_model_instance(data)
        try:
            account_id = int(data.get('_auth_user_id'))
        except (ValueError, TypeError):
            account_id = None
        obj.account_id = account_id
        return obj

Jika anda sedang berpindah dari sesi cached_db siap-pakai Django ke satu penyesuaian berdasarkan pada cached_db, anda harus menimpa awalan kunci cache untuk mencegah bentrokan namespace:

Code
class SessionStore(CachedDBStore):
    cache_key_prefix = 'mysessions.custom_cached_db_backend'

    # ...

ID Sesi dalam URL

The Django sessions framework is entirely, and solely, cookie-based. It does not fall back to putting session IDs in URLs as a last resort, as PHP does. This is an intentional design decision. Not only does that behavior make URLs ugly, it makes your site vulnerable to session-ID theft via the "Referer" header.

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