debian-django-reversion/docs/api.rst

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.. _api:
django-reversion API
====================
Use the django-reversion API to build version-controlled apps. See also :ref:`Views` and :ref:`Middleware`.
Overview
--------
Registering models
^^^^^^^^^^^^^^^^^^
Models must be registered with django-reversion before they can be used with the API.
.. code:: python
from django.db import models
import reversion
@reversion.register()
class YourModel(models.Model):
pass
.. Hint::
If you're using the :ref:`admin`, model registration is automatic. If youre using django-reversion in a management command, make sure you call ``django.contrib.admin.autodiscover()`` to load the admin modules before using the django-reversion API.
.. include:: /_include/post-register.rst
Creating revisions
^^^^^^^^^^^^^^^^^^
A *revision* represents one or more changes made to your model instances, grouped together as a single unit. You create a revision by creating a *revision block*. When you call ``save()`` on a registered model inside a revision block, it will be added to that revision.
.. code:: python
# Declare a revision block.
with reversion.create_revision():
# Save a new model instance.
obj = YourModel()
obj.name = "obj v1"
obj.save()
# Store some meta-information.
reversion.set_user(request.user)
reversion.set_comment("Created revision 1")
# Declare a new revision block.
with reversion.create_revision():
# Update the model instance.
obj.name = "obj v2"
obj.save()
# Store some meta-information.
reversion.set_user(request.user)
reversion.set_comment("Created revision 2")
.. Important::
Bulk actions, such as ``Queryset.update()``, do not send signals, so won't be noticed by django-reversion.
Loading revisions
^^^^^^^^^^^^^^^^^
Each model instance saved in a revision block is serialized as a :ref:`Version`. All versions in a revision block are associated with a single :ref:`Revision`.
You can load a :ref:`VersionQuerySet` of versions from the database. Versions are loaded with the most recent version first.
.. code:: python
from reversion.models import Version
# Load a queryset of versions for a specific model instance.
versions = Version.objects.get_for_object(instance)
assert len(versions) == 2
# Check the serialized data for the first version.
assert versions[1].field_dict["name"] = "obj v1"
# Check the serialized data for the second version.
assert versions[0].field_dict["name"] = "obj v2"
Revision metadata
^^^^^^^^^^^^^^^^^
:ref:`Revision` stores meta-information about the revision.
.. code:: python
# Check the revision metadata for the first revision.
assert versions[1].revision.comment = "Created revision 1"
assert versions[1].revision.user = request.user
assert isinstance(versions[1].revision.date_created, datetime.datetime)
# Check the revision metadata for the second revision.
assert versions[0].revision.comment = "Created revision 2"
assert versions[0].revision.user = request.user
assert isinstance(versions[0].revision.date_created, datetime.datetime)
Reverting revisions
^^^^^^^^^^^^^^^^^^^
Revert a :ref:`Revision` to restore the serialized model instances.
.. code:: python
# Revert the first revision.
versions[1].revision.revert()
# Check the model instance has been reverted.
obj.refresh_from_db()
assert obj.name == "version 1"
# Revert the second revision.
versions[0].revision.revert()
# Check the model instance has been reverted.
obj.refresh_from_db()
assert obj.name == "version 2"
Restoring deleted model instances
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Reverting a :ref:`Revision` will restore any serialized model instances that have been deleted.
.. code:: python
# Delete the model instance, but store the pk.
pk = obj.pk
obj.delete()
# Revert the second revision.
versions[0].revision.revert()
# Check the model has been restored to the database.
obj = YourModel.objects.get(pk=obj.pk)
assert obj.name == "version 2"
.. _registration-api:
Registration API
----------------
.. _register:
``reversion.register(model, **options)``
Registers a model with django-reversion.
Throws :ref:`RegistrationError` if the model has already been registered.
``model``
The Django model to register.
``fields=None``
An iterable of field names to include in the serialized data. If ``None``, all fields will be included.
``exclude=()``
An iterable of field names to exclude from the serialized data.
``follow=()``
An iterable of model relationships to follow when saving a version of this model. ``ForeignKey``, ``ManyToManyField`` and reversion ``ForeignKey`` relationships are supported. Any property that returns a ``Model`` or ``QuerySet`` is also supported.
``format="json"``
The name of a Django serialization format to use when saving the model instance.
``for_concrete_model=True``
If ``True`` proxy models will be saved under the same content type as their concrete model. If ``False``, proxy models will be saved under their own content type, effectively giving proxy models their own distinct history.
``ignore_duplicates=False``
If ``True``, then an additional check is performed to avoid saving duplicate versions for this model.
Checking for duplicate revisions adds significant overhead to the process of creating a revision. Don't enable it unless you really need it!
.. Hint::
By default, django-reversion will not register any parent classes of a model that uses multi-table inheritance. If you wish to also add parent models to your revision, you must explicitly add their ``parent_ptr`` fields to the ``follow`` parameter when you register the model.
.. include:: /_include/post-register.rst
``reversion.is_registered(model)``
Returns whether the given model has been registered with django-reversion.
``model``
The Django model to check.
``reversion.unregister(model)``
Unregisters the given model from django-reversion.
.. include:: /_include/throws-registration-error.rst
``model``
The Django model to unregister.
``reversion.get_registered_models()``
Returns an iterable of all registered models.
.. _revision-api:
Revision API
------------
``reversion.create_revision(manage_manually=False, using=None, atomic=True)``
Marks a block of code as a *revision block*. Can also be used as a decorator.
.. include:: /_include/create-revision-args.rst
``reversion.is_active()``
Returns whether there is currently an active revision block.
``reversion.is_manage_manually()``
Returns whether the current revision block is in ``manage_manually`` mode.
``reversion.set_user(user)``
Sets the user for the current revision.
.. include:: /_include/throws-revision-error.rst
``user``
A ``User`` model instance (or whatever your ``settings.AUTH_USER_MODEL`` is).
``reversion.get_user()``
Returns the user for the current revision.
.. include:: /_include/throws-revision-error.rst
.. _set_comment:
``reversion.set_comment(comment)``
Sets the comment for the current revision.
.. include:: /_include/throws-revision-error.rst
``comment``
The text comment for the revision.
``reversion.get_comment()``
Returns the comment for the current revision.
.. include:: /_include/throws-revision-error.rst
``reversion.set_date_created(date_created)``
Sets the creation date for the current revision.
.. include:: /_include/throws-revision-error.rst
``date_created``
The creation date for the revision.
``reversion.get_date_created()``
Returns the creation date for the current revision.
.. include:: /_include/throws-revision-error.rst
``reversion.add_meta(model, **values)``
Adds custom metadata to a revision.
.. include:: /_include/throws-revision-error.rst
``model``
A Django model to store the custom metadata. The model must have a ``ForeignKey`` or ``OneToOneField`` to :ref:`Revision`.
``**values``
Values to be stored on ``model`` when it is saved.
``reversion.add_to_revision(obj, model_db=None)``
Adds a model instance to a revision.
.. include:: /_include/throws-revision-error.rst
``obj``
A model instance to add to the revision.
.. include:: /_include/model-db-arg.rst
.. _VersionQuerySet:
reversion.models.VersionQuerySet
--------------------------------
A ``QuerySet`` of :ref:`Version`. The results are ordered with the most recent :ref:`Version` first.
``Version.objects.get_for_model(model, model_db=None)``
Returns a :ref:`VersionQuerySet` for the given model.
.. include:: /_include/throws-registration-error.rst
``model``
A registered model.
.. include:: /_include/model-db-arg.rst
``Version.objects.get_for_object(obj, model_db=None)``
Returns a :ref:`VersionQuerySet` for the given model instance.
.. include:: /_include/throws-registration-error.rst
``obj``
An instance of a registered model.
.. include:: /_include/model-db-arg.rst
``Version.objects.get_for_object_reference(model, pk, model_db=None)``
Returns a :ref:`VersionQuerySet` for the given model and primary key.
.. include:: /_include/throws-registration-error.rst
``model``
A registered model.
``pk``
The database primary key of a model instance.
.. include:: /_include/model-db-arg.rst
``Version.objects.get_deleted(model, model_db=None)``
Returns a :ref:`VersionQuerySet` for the given model containing versions where the serialized model no longer exists in the database.
.. include:: /_include/throws-registration-error.rst
``model``
A registered model.
``db``
The database to load the versions from.
.. include:: /_include/model-db-arg.rst
``Version.objects.get_unique()``
Returns an iterable of :ref:`Version`, where each version is unique for a given database, model instance, and set of serialized fields.
.. _Version:
reversion.models.Version
------------------------
Represents a single model instance serialized in a revision.
``Version.id``
The database primary key of the :ref:`Version`.
``Version.revision``
A ``ForeignKey`` to a :ref:`Revision` instance.
``Version.content_type``
The ``ContentType`` of the serialized model instance.
``Version.object_id``
The string representation of the serialized model instance's primary key.
``Version.db``
The Django database alias where the serialized model was saved.
``Version.format``
The name of the Django serialization format used to serialize the model instance.
``Version.serialized_data``
The raw serialized data of the model instance.
``Version.object_repr``
The stored snapshot of the model instance's ``__str__`` method when the instance was serialized.
``Version.field_dict``
A dictionary of stored model fields. This includes fields from any parent models in the same revision.
.. include:: /_include/throws-revert-error.rst
``Version.revert()``
Restores the serialized model instance to the database. To restore the entire revision, use :ref:`Revision.revert() <Revision-revert>`.
.. include:: /_include/throws-revert-error.rst
.. _Revision:
reversion.models.Revision
-------------------------
Contains metadata about a revision, and groups together all :ref:`Version` instances created in that revision.
``Revision.id``
The database primary key of the :ref:`Revision`.
``Revision.date_created``
A ``datetime`` when the revision was created.
``Revision.user``
The ``User`` that created the revision, or None.
``Revision.comment``
A text comment on the revision.
.. _Revision-revert:
``Revision.revert(delete=False)``
Restores all contained serialized model instances to the database.
.. include:: /_include/throws-revert-error.rst
``delete``
If ``True``, any model instances which have been created and are reachable by the ``follow`` clause of any model instances in this revision will be deleted. This effectively restores a group of related models to the state they were in when the revision was created.