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Code Issues 25 Releases Wiki Activity

Fixed #34311 -- Updated serialization docs from unique_together to UniqueConstraint.

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Willem Van Onsem 2023-02-04 22:48:44 +01:00 committed by Mariusz Felisiak
parent 473283d241
commit 292aacaf6c
1 changed files with 24 additions and 9 deletions
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33
docs/topics/serialization.txt
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@ -387,7 +387,12 @@ Consider the following two models::
birthdate = models.DateField()
class Meta:
unique_together = [['first_name', 'last_name']]
constraints = [
models.UniqueConstraint(
fields=["first_name", "last_name"],
name="unique_first_last_name",
),
]
class Book(models.Model):
name = models.CharField(max_length=100)
@ -431,7 +436,12 @@ name::
objects = PersonManager()
class Meta:
unique_together = [['first_name', 'last_name']]
constraints = [
models.UniqueConstraint(
fields=["first_name", "last_name"],
name="unique_first_last_name",
),
]
Now books can use that natural key to refer to ``Person`` objects::
@ -454,12 +464,12 @@ into the primary key of an actual ``Person`` object.
Whatever fields you use for a natural key must be able to uniquely
identify an object. This will usually mean that your model will
have a uniqueness clause (either unique=True on a single field, or
``unique_together`` over multiple fields) for the field or fields
in your natural key. However, uniqueness doesn't need to be
enforced at the database level. If you are certain that a set of
fields will be effectively unique, you can still use those fields
as a natural key.
have a uniqueness clause (either ``unique=True`` on a single field, or a
``UniqueConstraint`` or ``unique_together`` over multiple fields) for the
field or fields in your natural key. However, uniqueness doesn't need to be
enforced at the database level. If you are certain that a set of fields
will be effectively unique, you can still use those fields as a natural
key.
Deserialization of objects with no primary key will always check whether the
model's manager has a ``get_by_natural_key()`` method and if so, use it to
@ -479,7 +489,12 @@ Firstly, you need to add another method -- this time to the model itself::
objects = PersonManager()
class Meta:
unique_together = [['first_name', 'last_name']]
constraints = [
models.UniqueConstraint(
fields=["first_name", "last_name"],
name="unique_first_last_name",
),
]
def natural_key(self):
return (self.first_name, self.last_name)