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Fixed #36128 -- Clarified auto-generated unique constraint on m2m through models.

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Clifford Gama 2025-02-10 09:52:27 +02:00 • committed by Sarah Boyce
parent c09bceef68
commit ae2736ca3b
3 changed files with 22 additions and 8 deletions
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11
docs/ref/models/fields.txt
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@ -2028,13 +2028,6 @@ that control how the relationship functions.
:ref:`extra data with a many-to-many relationship
<intermediary-manytomany>`.
.. note::
If you don't want multiple associations between the same instances, add
a :class:`~django.db.models.UniqueConstraint` including the from and to
fields. Django's automatically generated many-to-many tables include
such a constraint.
.. note::
Recursive relationships using an intermediary model can't determine the
@ -2045,7 +2038,9 @@ that control how the relationship functions.
If you don't specify an explicit ``through`` model, there is still an
implicit ``through`` model class you can use to directly access the table
created to hold the association. It has three fields to link the models.
created to hold the association. It has three fields to link the models, a
primary key and two foreign keys. There is a unique constraint on the two
foreign keys.
If the source and target models differ, the following fields are
generated: