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Code Issues 32 Releases Wiki Activity

Clarified SeparateDatabaseAndState docs and added example of changing ManyToManyField.

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Co-Authored-By: Mariusz Felisiak <felisiak.mariusz@gmail.com>
Co-Authored-By: Carlton Gibson <carlton.gibson@noumenal.es>
Co-Authored-By: René Fleschenberg <rene@fleschenberg.net>
This commit is contained in:
Adam Johnson
2020-03-03 17:51:39 +00:00
committed by Mariusz Felisiak
parent a2f554249e
commit a9ee6872bd
2 changed files with 102 additions and 4 deletions
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20
docs/ref/migration-operations.txt
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@@ -419,12 +419,24 @@ if ``atomic=True`` is passed to the ``RunPython`` operation.
.. class:: SeparateDatabaseAndState(database_operations=None, state_operations=None)
A highly specialized operation that let you mix and match the database
A highly specialized operation that lets you mix and match the database
(schema-changing) and state (autodetector-powering) aspects of operations.
It accepts two lists of operations, and when asked to apply state will use the
state list, and when asked to apply changes to the database will use the database
list. Do not use this operation unless you're very sure you know what you're doing.
It accepts two lists of operations. When asked to apply state, it will use the
``state_operations`` list (this is a generalized version of :class:`RunSQL`'s
``state_operations`` argument). When asked to apply changes to the database, it
will use the ``database_operations`` list.
If the actual state of the database and Django's view of the state get out of
sync, this can break the migration framework, even leading to data loss. It's
worth exercising caution and checking your database and state operations
carefully. You can use :djadmin:`sqlmigrate` and :djadmin:`dbshell` to check
your database operations. You can use :djadmin:`makemigrations`, especially
with :option:`--dry-run<makemigrations --dry-run>`, to check your state
operations.
For an example using ``SeparateDatabaseAndState``, see
:ref:`changing-a-manytomanyfield-to-use-a-through-model`.
.. _writing-your-own-migration-operation: