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95 lines
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95 lines
3.0 KiB
Plaintext
=================================
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Providing initial data for models
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=================================
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It's sometimes useful to pre-populate your database with hard-coded data when
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you're first setting up an app. You can provide initial data with fixtures or
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migrations.
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.. _initial-data-via-fixtures:
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Providing initial data with fixtures
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====================================
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A fixture is a collection of data that Django knows how to import into a
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database. The most straightforward way of creating a fixture if you've already
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got some data is to use the :djadmin:`manage.py dumpdata <dumpdata>` command.
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Or, you can write fixtures by hand; fixtures can be written as JSON, XML or YAML
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(with PyYAML_ installed) documents. The :doc:`serialization documentation
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</topics/serialization>` has more details about each of these supported
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:ref:`serialization formats <serialization-formats>`.
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.. _PyYAML: http://www.pyyaml.org/
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As an example, though, here's what a fixture for a simple ``Person`` model might
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look like in JSON:
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.. code-block:: js
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[
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{
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"model": "myapp.person",
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"pk": 1,
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"fields": {
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"first_name": "John",
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"last_name": "Lennon"
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}
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},
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{
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"model": "myapp.person",
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"pk": 2,
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"fields": {
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"first_name": "Paul",
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"last_name": "McCartney"
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}
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}
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]
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And here's that same fixture as YAML:
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.. code-block:: none
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- model: myapp.person
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pk: 1
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fields:
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first_name: John
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last_name: Lennon
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- model: myapp.person
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pk: 2
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fields:
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first_name: Paul
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last_name: McCartney
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You'll store this data in a ``fixtures`` directory inside your app.
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Loading data is easy: just call :djadmin:`manage.py loaddata <loaddata>`
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``<fixturename>``, where ``<fixturename>`` is the name of the fixture file
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you've created. Each time you run :djadmin:`loaddata`, the data will be read
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from the fixture and re-loaded into the database. Note this means that if you
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change one of the rows created by a fixture and then run :djadmin:`loaddata`
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again, you'll wipe out any changes you've made.
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Where Django finds fixture files
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--------------------------------
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By default, Django looks in the ``fixtures`` directory inside each app for
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fixtures. You can set the :setting:`FIXTURE_DIRS` setting to a list of
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additional directories where Django should look.
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When running :djadmin:`manage.py loaddata <loaddata>`, you can also
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specify a path to a fixture file, which overrides searching the usual
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directories.
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.. seealso::
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Fixtures are also used by the :ref:`testing framework
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<topics-testing-fixtures>` to help set up a consistent test environment.
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Providing initial data with migrations
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======================================
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If you want to automatically load initial data for an app, don't use fixtures.
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Instead, create a migration for your application with
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:class:`~django.db.migrations.operations.RunPython` or
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:class:`~django.db.migrations.operations.RunSQL` operations.
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