Providing initial data for models

It’s sometimes useful to pre-populate your database with hard-coded data when you’re first setting up an app. You can provide initial data with migrations or fixtures.

Providing initial data with migrations

If you want to automatically load initial data for an app, create a data migration. Migrations are run when setting up the test database, so the data will be available there, subject to some limitations.

Providing data with fixtures

You can also provide data using fixtures, however, this data isn’t loaded automatically, except if you use TransactionTestCase.fixtures.

A fixture is a collection of data that Django knows how to import into a database. The most straightforward way of creating a fixture if you’ve already got some data is to use the manage.py dumpdata command. Or, you can write fixtures by hand; fixtures can be written as JSON, XML or YAML (with PyYAML installed) documents. The serialization documentation has more details about each of these supported serialization formats.

As an example, though, here’s what a fixture for a simple Person model might look like in JSON:

[
  {
    "model": "myapp.person",
    "pk": 1,
    "fields": {
      "first_name": "John",
      "last_name": "Lennon"
    }
  },
  {
    "model": "myapp.person",
    "pk": 2,
    "fields": {
      "first_name": "Paul",
      "last_name": "McCartney"
    }
  }
]

And here’s that same fixture as YAML:

- model: myapp.person
  pk: 1
  fields:
    first_name: John
    last_name: Lennon
- model: myapp.person
  pk: 2
  fields:
    first_name: Paul
    last_name: McCartney

You’ll store this data in a fixtures directory inside your app.

Loading data is easy: just call manage.py loaddata <fixturename>, where <fixturename> is the name of the fixture file you’ve created. Each time you run loaddata, the data will be read from the fixture and re-loaded into the database. Note this means that if you change one of the rows created by a fixture and then run loaddata again, you’ll wipe out any changes you’ve made.

Where Django finds fixture files

By default, Django looks in the fixtures directory inside each app for fixtures. You can set the FIXTURE_DIRS setting to a list of additional directories where Django should look.

When running manage.py loaddata, you can also specify a path to a fixture file, which overrides searching the usual directories.

See also

Fixtures are also used by the testing framework to help set up a consistent test environment.

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