47 lines
1.2 KiB
Plaintext
47 lines
1.2 KiB
Plaintext
===========================
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Check constraints reference
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===========================
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.. module:: django.db.models.constraints
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.. currentmodule:: django.db.models
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.. versionadded:: 2.2
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The ``CheckConstraint`` class creates database check constraints. They are
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added in the model :attr:`Meta.constraints
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<django.db.models.Options.constraints>` option. This document
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explains the API references of :class:`CheckConstraint`.
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.. admonition:: Referencing built-in constraints
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Constraints are defined in ``django.db.models.constraints``, but for
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convenience they're imported into :mod:`django.db.models`. The standard
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convention is to use ``from django.db import models`` and refer to the
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constraints as ``models.CheckConstraint``.
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``CheckConstraint`` options
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===========================
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.. class:: CheckConstraint(*, check, name)
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Creates a check constraint in the database.
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``check``
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---------
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.. attribute:: CheckConstraint.check
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A :class:`Q` object that specifies the check you want the constraint to
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enforce.
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For example ``CheckConstraint(check=Q(age__gte=18), name='age_gte_18')``
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ensures the age field is never less than 18.
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``name``
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--------
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.. attribute:: CheckConstraint.name
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The name of the constraint.
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