Commit f287bec5 authored by Markus Holtermann's avatar Markus Holtermann
Browse files

Fixed #24184 -- Prevented automatic soft-apply of migrations

Previously Django only checked for the table name in CreateModel
operations in initial migrations and faked the migration automatically.
This led to various errors and unexpected behavior. The newly introduced
--fake-initial flag to the migrate command must be passed to get the
same behavior again. With this change Django will bail out in with a
"duplicate relation / table" error instead.

Thanks Carl Meyer and Tim Graham for the documentation update, report
and review.
parent b4e1090a
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+7 −1
Original line number Diff line number Diff line
@@ -40,6 +40,10 @@ class Command(BaseCommand):
                'Defaults to the "default" database.')
        parser.add_argument('--fake', action='store_true', dest='fake', default=False,
            help='Mark migrations as run without actually running them')
        parser.add_argument('--fake-initial', action='store_true', dest='fake_initial', default=False,
            help='Detect if tables already exist and fake-apply initial migrations if so. Make sure '
                 'that the current database schema matches your initial migration before using this '
                 'flag. Django will only check for an existing table name.')
        parser.add_argument('--list', '-l', action='store_true', dest='list', default=False,
            help='Show a list of all known migrations and which are applied')

@@ -186,7 +190,9 @@ class Command(BaseCommand):
                        "apply them."
                    ))
        else:
            executor.migrate(targets, plan, fake=options.get("fake", False))
            fake = options.get("fake")
            fake_initial = options.get("fake_initial")
            executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial)

        # Send the post_migrate signal, so individual apps can do whatever they need
        # to do at this point.
+9 −8
Original line number Diff line number Diff line
@@ -62,7 +62,7 @@ class MigrationExecutor(object):
                        applied.add(migration)
        return plan

    def migrate(self, targets, plan=None, fake=False):
    def migrate(self, targets, plan=None, fake=False, fake_initial=False):
        """
        Migrates the database up to the given targets.

@@ -91,7 +91,7 @@ class MigrationExecutor(object):
        # Phase 2 -- Run the migrations
        for migration, backwards in plan:
            if not backwards:
                self.apply_migration(states[migration], migration, fake=fake)
                self.apply_migration(states[migration], migration, fake=fake, fake_initial=fake_initial)
            else:
                self.unapply_migration(states[migration], migration, fake=fake)

@@ -113,18 +113,19 @@ class MigrationExecutor(object):
            statements.extend(schema_editor.collected_sql)
        return statements

    def apply_migration(self, state, migration, fake=False):
    def apply_migration(self, state, migration, fake=False, fake_initial=False):
        """
        Runs a migration forwards.
        """
        if self.progress_callback:
            self.progress_callback("apply_start", migration, fake)
        if not fake:
            if fake_initial:
                # Test to see if this is an already-applied initial migration
                applied, state = self.detect_soft_applied(state, migration)
                if applied:
                    fake = True
            else:
            if not fake:
                # Alright, do it normally
                with self.connection.schema_editor() as schema_editor:
                    state = migration.apply(state, schema_editor)
+13 −0
Original line number Diff line number Diff line
@@ -721,6 +721,19 @@ be warned that using ``--fake`` runs the risk of putting the migration state
table into a state where manual recovery will be needed to make migrations
run correctly.

.. versionadded:: 1.8

.. django-admin-option:: --fake-initial

The ``--fake-initial`` option can be used to allow Django to skip an app's
initial migration if all database tables with the names of all models created
by all :class:`~django.db.migrations.operations.CreateModel` operations in that
migration already exist. This option is intended for use when first running
migrations against a database that preexisted the use of migrations. This
option does not, however, check for matching database schema beyond matching
table names and so is only safe to use if you are confident that your existing
schema matches what is recorded in your initial migration.

.. deprecated:: 1.8

    The ``--list`` option has been moved to the :djadmin:`showmigrations`
+5 −0
Original line number Diff line number Diff line
@@ -1135,6 +1135,11 @@ Miscellaneous
  has been removed by a migration and replaced by a property. That means it's
  not possible to query or filter a ``ContentType`` by this field any longer.

* :djadmin:`migrate` now accepts the :djadminopt:`--fake-initial` option to
  allow faking initial migrations. In 1.7 initial migrations were always
  automatically faked if all tables created in an initial migration already
  existed.

.. _deprecated-features-1.8:

Features deprecated in 1.8
+27 −12
Original line number Diff line number Diff line
@@ -140,6 +140,13 @@ developers (or your production servers) check out the code, they'll
get both the changes to your models and the accompanying migration at the
same time.

.. versionadded:: 1.8

If you want to give the migration(s) a meaningful name instead of a generated
one, you can use the :djadminopt:`--name` option::

    $ python manage.py makemigrations --name changed_my_model your_app_label

Version control
~~~~~~~~~~~~~~~

@@ -282,10 +289,12 @@ need to convert it to use migrations; this is a simple process::

    $ python manage.py makemigrations your_app_label

This will make a new initial migration for your app. Now, when you run
:djadmin:`migrate`, Django will detect that you have an initial migration
*and* that the tables it wants to create already exist, and will mark the
migration as already applied.
This will make a new initial migration for your app. Now, run ``python
manage.py migrate --fake-initial``, and Django will detect that you have an
initial migration *and* that the tables it wants to create already exist, and
will mark the migration as already applied. (Without the
:djadminopt:`--fake-initial` flag, the :djadmin:`migrate` command would error
out because the tables it wants to create already exist.)

Note that this only works given two things:

@@ -297,12 +306,11 @@ Note that this only works given two things:
  that your database doesn't match your models, you'll just get errors when
  migrations try to modify those tables.

.. versionadded:: 1.8

If you want to give the migration(s) a meaningful name instead of a generated one,
you can use the :djadminopt:`--name` option::
.. versionchanged: 1.8

    $ python manage.py makemigrations --name changed_my_model your_app_label
    The ``--fake-initial`` flag to :djadmin:`migrate` was added. Previously,
    Django would always automatically fake-apply initial migrations if it
    detected that the tables exist.

.. _historical-models:

@@ -706,9 +714,10 @@ If you already have pre-existing migrations created with
  ``__init__.py`` - make sure you remove the ``.pyc`` files too.
* Run ``python manage.py makemigrations``. Django should see the empty
  migration directories and make new initial migrations in the new format.
* Run ``python manage.py migrate``. Django will see that the tables for the
  initial migrations already exist and mark them as applied without running
  them.
* Run ``python manage.py migrate --fake-initial``. Django will see that the
  tables for the initial migrations already exist and mark them as applied
  without running them. (Django won't check that the table schema match your
  models, just that the right table names exist).

That's it! The only complication is if you have a circular dependency loop
of foreign keys; in this case, ``makemigrations`` might make more than one
@@ -716,6 +725,12 @@ initial migration, and you'll need to mark them all as applied using::

    python manage.py migrate --fake yourappnamehere

.. versionchanged:: 1.8

    The :djadminopt:`--fake-initial` flag was added to :djadmin:`migrate`;
    previously, initial migrations were always automatically fake-applied if
    existing tables were detected.

Libraries/Third-party Apps
~~~~~~~~~~~~~~~~~~~~~~~~~~

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