---
title: "Constraints reference"
version: 3.2
locale: id
source: https://docs.djangoproject.com/id/3.2/ref/models/constraints/
canonical: https://djangodocs.dev/id/3.2/ref/models/constraints/
---
# Constraints reference

The classes defined in this module create database constraints. They are added
in the model [`Meta.constraints`](/id/3.2/ref/models/options/#django.db.models.Options.constraints)
option.

> **Referencing built-in constraints**
>
> Constraints are defined in `django.db.models.constraints`, but for
> convenience they're imported into [`django.db.models`](/id/3.2/topics/db/models/#module-django.db.models). The standard
> convention is to use `from django.db import models` and refer to the
> constraints as `models.<Foo>Constraint`.

> **Constraints in abstract base classes**
>
> You must always specify a unique name for the constraint. As such, you
> cannot normally specify a constraint on an abstract base class, since the
> [`Meta.constraints`](/id/3.2/ref/models/options/#django.db.models.Options.constraints) option is
> inherited by subclasses, with exactly the same values for the attributes
> (including `name`) each time. To work around name collisions, part of the
> name may contain `'%(app_label)s'` and `'%(class)s'`, which are
> replaced, respectively, by the lowercased app label and class name of the
> concrete model. For example `CheckConstraint(check=Q(age__gte=18),
> name='%(app_label)s_%(class)s_is_adult')`.

> **Validation of Constraints**
>
> In general constraints are **not** checked during `full_clean()`, and do
> not raise `ValidationError`s. Rather you'll get a database integrity
> error on `save()`. `UniqueConstraint`s without a
> [`condition`](#django.db.models.UniqueConstraint.condition) (i.e. non-partial unique constraints)
> are different in this regard, in that they leverage the existing
> `validate_unique()` logic, and thus enable two-stage validation. In
> addition to `IntegrityError` on `save()`, `ValidationError` is also
> raised during model validation when the `UniqueConstraint` is violated.

## `CheckConstraint`

#### `class CheckConstraint(* (Keyword-only parameters separator (PEP 3102)), check, name)`

Creates a check constraint in the database.

### `check`

#### `CheckConstraint.check`

A [`Q`](/id/3.2/ref/models/querysets/#django.db.models.Q) object or boolean [`Expression`](/id/3.2/ref/models/expressions/#django.db.models.Expression) that
specifies the check you want the constraint to enforce.

For example, `CheckConstraint(check=Q(age__gte=18), name='age_gte_18')`
ensures the age field is never less than 18.

> **Changed in Django 3.1**
>
> Support for boolean [`Expression`](/id/3.2/ref/models/expressions/#django.db.models.Expression) was added.

### `name`

#### `CheckConstraint.name`

The name of the constraint. You must always specify a unique name for the
constraint.

## `UniqueConstraint`

#### `class UniqueConstraint(* (Keyword-only parameters separator (PEP 3102)), fields, name, condition=None, deferrable=None, include=None, opclasses=())`

Creates a unique constraint in the database.

### `fields`

#### `UniqueConstraint.fields`

A list of field names that specifies the unique set of columns you want the
constraint to enforce.

For example, `UniqueConstraint(fields=['room', 'date'],
name='unique_booking')` ensures each room can only be booked once for each
date.

### `name`

#### `UniqueConstraint.name`

The name of the constraint. You must always specify a unique name for the
constraint.

### `condition`

#### `UniqueConstraint.condition`

A [`Q`](/id/3.2/ref/models/querysets/#django.db.models.Q) object that specifies the condition you want the constraint to
enforce.

Sebagai contoh:

```
UniqueConstraint(fields=['user'], condition=Q(status='DRAFT'), name='unique_draft_user')
```

ensures that each user only has one draft.

These conditions have the same database restrictions as
[`Index.condition`](/id/3.2/ref/models/indexes/#django.db.models.Index.condition).

### `deferrable`

#### `UniqueConstraint.deferrable`

> **New in Django 3.1**

Set this parameter to create a deferrable unique constraint. Accepted values
are `Deferrable.DEFERRED` or `Deferrable.IMMEDIATE`. For example:

```
from django.db.models import Deferrable, UniqueConstraint

UniqueConstraint(
    name='unique_order',
    fields=['order'],
    deferrable=Deferrable.DEFERRED,
)
```

By default constraints are not deferred. A deferred constraint will not be
enforced until the end of the transaction. An immediate constraint will be
enforced immediately after every command.

> **MySQL, MariaDB, and SQLite.**
>
> Deferrable unique constraints are ignored on MySQL, MariaDB, and SQLite as
> neither supports them.

> **Warning**
>
> Deferred unique constraints may lead to a [performance penalty](https://www.postgresql.org/docs/current/sql-createtable.html#id-1.9.3.85.9.4).

### `include`

#### `UniqueConstraint.include`

> **New in Django 3.2**

A list or tuple of the names of the fields to be included in the covering
unique index as non-key columns. This allows index-only scans to be used for
queries that select only included fields ([`include`](#django.db.models.UniqueConstraint.include))
and filter only by unique fields ([`fields`](#django.db.models.UniqueConstraint.fields)).

Sebagai contoh:

```
UniqueConstraint(name='unique_booking', fields=['room', 'date'], include=['full_name'])
```

will allow filtering on `room` and `date`, also selecting `full_name`,
while fetching data only from the index.

`include` is supported only on PostgreSQL.

Non-key columns have the same database restrictions as [`Index.include`](/id/3.2/ref/models/indexes/#django.db.models.Index.include).

### `opclasses`

#### `UniqueConstraint.opclasses`

> **New in Django 3.2**

The names of the [PostgreSQL operator classes](https://www.postgresql.org/docs/current/indexes-opclass.html) to use for
this unique index. If you require a custom operator class, you must provide one
for each field in the index.

Sebagai contoh:

```
UniqueConstraint(name='unique_username', fields=['username'], opclasses=['varchar_pattern_ops'])
```

creates a unique index on `username` using `varchar_pattern_ops`.

`opclasses` are ignored for databases besides PostgreSQL.