Installation¶

Requirements¶

Python 3.14+
Django 6.0
PostgreSQL (any currently supported version)
django-pgtrigger 4.17+ (pulled in automatically)

Install¶

pip install django-pgconstraints

or with uv:

uv add django-pgconstraints

Register the app¶

Add pgtrigger and django_pgconstraints to INSTALLED_APPS. Both are required: the trigger classes inherit from pgtrigger.Trigger and are installed via django-pgtrigger's machinery.

INSTALLED_APPS = [
    # ...
    "pgtrigger",
    "django_pgconstraints",
    # your apps
]

Where triggers go¶

Triggers live in Meta.triggers, a hook contributed by django-pgtrigger. They do not go in Meta.constraints:

class OrderLine(models.Model):
    ...

    class Meta:
        triggers = [
            CheckConstraintTrigger(
                condition=Q(quantity__gt=0),
                name="orderline_qty_positive",
            ),
        ]

Putting them in Meta.constraints would silently do nothing at the database level, so django_pgconstraints ships a system check (pgconstraints.E001) that fails manage.py check if you make that mistake.

Installing the triggers in the database¶

django-pgtrigger installs triggers as part of migrate. After adding or changing a trigger, run:

python manage.py makemigrations
python manage.py migrate

See the django-pgtrigger installation docs for the other installation strategies (pgtrigger install, schema-editor mode, etc.).