A list of all the signals that Django sends. All built-in signals are sent\nusing the send() method.
The django.db.models.signals module defines a set of signals sent by the\nmodel system.
pre_initLink to this heading#Whenever you instantiate a Django model, this signal is sent at the beginning\nof the model’s __init__() method.
Arguments sent with this signal:
\nsenderThe model class that just had an instance created.
\nargsA list of positional arguments passed to __init__().
kwargsA dictionary of keyword arguments passed to __init__().
For example, the tutorial has this line:
\nq = Question(question_text="What's new?", pub_date=timezone.now())\nThe arguments sent to a pre_init handler would be:
Argument | \nValue | \n
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post_initLink to this heading#Like pre_init, but this one is sent when the __init__() method finishes.
Arguments sent with this signal:
\nsenderAs above: the model class that just had an instance created.
\ninstanceThe actual instance of the model that’s just been created.
\n\npre_saveLink to this heading#This is sent at the beginning of a model’s save()\nmethod.
Arguments sent with this signal:
\nsenderThe model class.
\ninstanceThe actual instance being saved.
\nrawA boolean; True if the model is saved exactly as presented\n(i.e. when loading a fixture). One should not query/modify other\nrecords in the database as the database might not be in a\nconsistent state yet.
usingThe database alias being used.
\nupdate_fieldsThe set of fields to update as passed to Model.save(), or None\nif update_fields wasn’t passed to save().
post_saveLink to this heading#Like pre_save, but sent at the end of the\nsave() method.
Arguments sent with this signal:
\nsenderThe model class.
\ninstanceThe actual instance being saved.
\ncreatedA boolean; True if a new record was created.
rawA boolean; True if the model is saved exactly as presented\n(i.e. when loading a fixture). One should not query/modify other\nrecords in the database as the database might not be in a\nconsistent state yet.
usingThe database alias being used.
\nupdate_fieldsThe set of fields to update as passed to Model.save(), or None\nif update_fields wasn’t passed to save().
pre_deleteLink to this heading#Sent at the beginning of a model’s delete()\nmethod and a queryset’s delete() method.
Arguments sent with this signal:
\nsenderThe model class.
\ninstanceThe actual instance being deleted.
\nusingThe database alias being used.
\npost_deleteLink to this heading#Like pre_delete, but sent at the end of a model’s\ndelete() method and a queryset’s\ndelete() method.
Arguments sent with this signal:
\nsenderThe model class.
\ninstanceThe actual instance being deleted.
\nNote that the object will no longer be in the database, so be very\ncareful what you do with this instance.
\nusingThe database alias being used.
\nm2m_changedLink to this heading#Sent when a ManyToManyField is changed on a model\ninstance. Strictly speaking, this is not a model signal since it is sent by the\nManyToManyField, but since it complements the\npre_save/post_save and pre_delete/post_delete\nwhen it comes to tracking changes to models, it is included here.
Arguments sent with this signal:
\nsenderThe intermediate model class describing the\nManyToManyField. This class is automatically\ncreated when a many-to-many field is defined; you can access it using the\nthrough attribute on the many-to-many field.
instanceThe instance whose many-to-many relation is updated. This can be an\ninstance of the sender, or of the class the\nManyToManyField is related to.
actionA string indicating the type of update that is done on the relation.\nThis can be one of the following:
\n"pre_add"Sent before one or more objects are added to the relation.
\n"post_add"Sent after one or more objects are added to the relation.
\n"pre_remove"Sent before one or more objects are removed from the relation.
\n"post_remove"Sent after one or more objects are removed from the relation.
\n"pre_clear"Sent before the relation is cleared.
\n"post_clear"Sent after the relation is cleared.
\nreverseIndicates which side of the relation is updated (i.e., if it is the\nforward or reverse relation that is being modified).
\nmodelThe class of the objects that are added to, removed from or cleared\nfrom the relation.
\npk_setFor the pre_add and post_add actions, this is a set of primary key\nvalues that will be, or have been, added to the relation. This may be a\nsubset of the values submitted to be added, since inserts must filter\nexisting values in order to avoid a database IntegrityError.
For the pre_remove and post_remove actions, this is a set of\nprimary key values that was submitted to be removed from the relation. This\nis not dependent on whether the values actually will be, or have been,\nremoved. In particular, non-existent values may be submitted, and will\nappear in pk_set, even though they have no effect on the database.
For the pre_clear and post_clear actions, this is None.
usingThe database alias being used.
\nFor example, if a Pizza can have multiple Topping objects, modeled\nlike this:
class Topping(models.Model):\n # ...\n pass\n\nclass Pizza(models.Model):\n # ...\n toppings = models.ManyToManyField(Topping)\nIf we connected a handler like this:
\nfrom django.db.models.signals import m2m_changed\n\ndef toppings_changed(sender, **kwargs):\n # Do something\n pass\n\nm2m_changed.connect(toppings_changed, sender=Pizza.toppings.through)\nand then did something like this:
\n>>> p = Pizza.objects.create(...)\n>>> t = Topping.objects.create(...)\n>>> p.toppings.add(t)\nthe arguments sent to a m2m_changed handler (toppings_changed in\nthe example above) would be:
Argument | \nValue | \n
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And if we would then do something like this:
\n>>> t.pizza_set.remove(p)\nthe arguments sent to a m2m_changed handler would be:
Argument | \nValue | \n
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class_preparedLink to this heading#Sent whenever a model class has been “prepared” – that is, once model has\nbeen defined and registered with Django’s model system. Django uses this\nsignal internally; it’s not generally used in third-party applications.
\nSince this signal is sent during the app registry population process, and\nAppConfig.ready() runs after the app\nregistry is fully populated, receivers cannot be connected in that method.\nOne possibility is to connect them AppConfig.__init__() instead, taking\ncare not to import models or trigger calls to the app registry.
Arguments that are sent with this signal:
\nsenderThe model class which was just prepared.
\nSignals sent by django-admin.
\npre_migrateLink to this heading#Sent by the migrate command before it starts to install an\napplication. It’s not emitted for applications that lack a models module.
Arguments sent with this signal:
\nsenderAn AppConfig instance for the application about to\nbe migrated/synced.
app_configSame as sender.
verbosityIndicates how much information manage.py is printing on screen. See\nthe --verbosity flag for details.
Functions which listen for pre_migrate should adjust what they\noutput to the screen based on the value of this argument.
interactiveIf interactive is True, it’s safe to prompt the user to input\nthings on the command line. If interactive is False, functions\nwhich listen for this signal should not try to prompt for anything.
For example, the django.contrib.auth app only prompts to create a\nsuperuser when interactive is True.
usingThe alias of database on which a command will operate.
\nplanThe migration plan that is going to be used for the migration run. While\nthe plan is not public API, this allows for the rare cases when it is\nnecessary to know the plan. A plan is a list of two-tuples with the first\nitem being the instance of a migration class and the second item showing\nif the migration was rolled back (True) or applied (False).
appsAn instance of Apps containing the state of the\nproject before the migration run. It should be used instead of the global\napps registry to retrieve the models you\nwant to perform operations on.
post_migrateLink to this heading#Sent at the end of the migrate (even if no migrations are run) and\nflush commands. It’s not emitted for applications that lack a\nmodels module.
Handlers of this signal must not perform database schema alterations as doing\nso may cause the flush command to fail if it runs during the\nmigrate command.
Arguments sent with this signal:
\nsenderAn AppConfig instance for the application that was\njust installed.
app_configSame as sender.
verbosityIndicates how much information manage.py is printing on screen. See\nthe --verbosity flag for details.
Functions which listen for post_migrate should adjust what they\noutput to the screen based on the value of this argument.
interactiveIf interactive is True, it’s safe to prompt the user to input\nthings on the command line. If interactive is False, functions\nwhich listen for this signal should not try to prompt for anything.
For example, the django.contrib.auth app only prompts to create a\nsuperuser when interactive is True.
usingThe database alias used for synchronization. Defaults to the default\ndatabase.
planThe migration plan that was used for the migration run. While the plan is\nnot public API, this allows for the rare cases when it is necessary to\nknow the plan. A plan is a list of two-tuples with the first item being\nthe instance of a migration class and the second item showing if the\nmigration was rolled back (True) or applied (False).
appsAn instance of Apps containing the state of the\nproject after the migration run. It should be used instead of the global\napps registry to retrieve the models you\nwant to perform operations on.
For example, you could register a callback in an\nAppConfig like this:
from django.apps import AppConfig\nfrom django.db.models.signals import post_migrate\n\ndef my_callback(sender, **kwargs):\n # Your specific logic here\n pass\n\nclass MyAppConfig(AppConfig):\n ...\n\n def ready(self):\n post_migrate.connect(my_callback, sender=self)\nSignals sent by the core framework when processing a request.
\nrequest_startedLink to this heading#Sent when Django begins processing an HTTP request.
\nArguments sent with this signal:
\nsenderThe handler class – e.g. django.core.handlers.wsgi.WsgiHandler – that\nhandled the request.
environThe environ dictionary provided to the request.
request_finishedLink to this heading#Sent when Django finishes delivering an HTTP response to the client.
\nArguments sent with this signal:
\nsenderThe handler class, as above.
\ngot_request_exceptionLink to this heading#This signal is sent whenever Django encounters an exception while processing an incoming HTTP request.
\nArguments sent with this signal:
\nsenderUnused (always None).
requestThe HttpRequest object.
Signals only sent when running tests.
\nsetting_changedLink to this heading#This signal is sent when the value of a setting is changed through the\ndjango.test.TestCase.settings() context manager or the\ndjango.test.override_settings() decorator/context manager.
It’s actually sent twice: when the new value is applied (“setup”) and when the\noriginal value is restored (“teardown”). Use the enter argument to\ndistinguish between the two.
You can also import this signal from django.core.signals to avoid importing\nfrom django.test in non-test situations.
Arguments sent with this signal:
\nsenderThe settings handler.
\nsettingThe name of the setting.
\nvalueThe value of the setting after the change. For settings that initially\ndon’t exist, in the “teardown” phase, value is None.
enterA boolean; True if the setting is applied, False if restored.
template_renderedLink to this heading#Sent when the test system renders a template. This signal is not emitted during\nnormal operation of a Django server – it is only available during testing.
\nArguments sent with this signal:
\n\nSignals sent by the database wrapper when a database connection is\ninitiated.
\nconnection_createdLink to this heading#Sent when the database wrapper makes the initial connection to the\ndatabase. This is particularly useful if you’d like to send any post\nconnection commands to the SQL backend.
\nArguments sent with this signal:
\nsenderThe database wrapper class – i.e.\ndjango.db.backends.postgresql.DatabaseWrapper or\ndjango.db.backends.mysql.DatabaseWrapper, etc.
connectionThe database connection that was opened. This can be used in a\nmultiple-database configuration to differentiate connection signals\nfrom different databases.
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