Django Fixtures Tutorial: How to use dumpdata and loaddata

• By Will Vincent
• Last updated Oct 4, 2023

A fixture is a collection of data that can be dumped or loaded into a Django database. It is serialized into a text-based format such as JSON or XML and used to provide initial data for local development or pre-populate a database with content for tests. Used properly, fixtures are a powerful feature that can improve all Django developer's productivity.

Create a Fixture with dumpdata

If you already have an existing Django project, it is possible to "dump" the database data into a fixture using the dumpdata management command. The basic syntax is as follows:

$ python manage.py dumpdata [app_name.ModelName]

For example, use the following command to dump the entire database into a file called db.json (JSON is the default file format).

$ python manage.py dumpdata > db.json

The resulting db.json file can then be viewed and used. If you are using VSCode to view the resulting JSON file, a quick tip to organize the code is to type Shift + Alt + F on Windows or Shift + Option + F on macOS.

It is also possible to dump only a specific model. For example, if you had a books app and only wanted to dump the Author model, you could output the data into a db_books_author.json file.

$ python manage.py dumpdata books.Author > db_books_author.json

Load a Fixture using loaddata

To populate a database using a fixture, use the loaddata management command with the following basic syntax:

$ python manage.py loaddata fixture_file

So, for example, if you deleted your SQLite database in a Django project and wanted to reload it with a db.json fixture containing all its contents, you would use the following command:

$ python manage.py loaddata db.json

Tips for Using Fixtures

1. Testing: Fixtures are beneficial for automated testing when you need a known set of data to test against.
2. Compression: If you have very large fixtures, it is possible to compress them using the bz2, gz, lzma, or xz formats.
3. Secret Data: Be mindful of secret or sensitive data within your fixtures. If you are storing or distributing them, ensure they don't include private information.
4. Versioning: Django models often evolve throughout a project's lifetime, and fixtures must be updated alongside these changes. Use versioning to track updates to your fixtures over time.
5. Natural Keys: Using a natural key can make fixtures more readable, however, ensure any natural keys are unique to prevent future conflicts.

Conclusion

Fixtures are a robust and proven way to manage data within Django applications. They make it much easier to import/export content and help with automated testing. While they come with a few limitations--most notably around security--they are an essential tool in a professional Django developers toolkit.