· Hakan Çelik · Django / Database · 3 dk okuma

Using Dumpdata and Loaddata

Main source | djangoproject.com/en/2.1/

Using Dumpdata and Loaddata

Dumpdata

Main source | djangoproject.com/en/2.1/

Dumpdata is a command available among Django’s default commands, accessible via python manage.py. Its purpose is to create a backup (fixture) of your database in a specified format. If you wish, you can use the loaddata command to write this backup into a newly created database. Those curious about the source code of the dumpdata command can click the link I provided to study it and get more detailed information firsthand: dumpdata.py

Usage

General usage: python manage.py dumpdata [app_label[.ModelName] [app_label[.ModelName] ...]]

Parameters

  • --all -a When these parameters are used, Django uses the base manager to dump all models.
  • --format FORMAT With the format parameter, you can specify which format to use when dumping. The default format is json and there are three formats available: xml, json, yaml.
  • --indent INDENT Specifies the indentation level of the output. Default is JSON. Supported formats are listed in the serialization formats documentation.
  • --exclude EXCLUDE, -e EXCLUDE During backup, there may be certain parts you don’t want to back up — this parameter is for that purpose.
  • --database DATABASE A helpful parameter for those using multiple databases — it specifies which database to use for the backup. Defaults to the default database.
  • --natural-foreign Uses the natural_key() model method to serialize any foreign key and many-to-many relationships with objects that define this method. If you are dumping contrib.auth Permission objects or contrib.contenttypes ContentType objects, you should probably use this flag. For more details about this and the next option, see the documentation on natural keys.
  • --natural-primary Omits the primary key in the serialized data for this object, as it can be calculated during deserialization.
  • --pks PRIMARY_KEYS Outputs only the objects specified by a comma-separated list of primary keys. This is only available when dumping one model. By default, all records for the model are output.
  • --output OUTPUT, -o OUTPUT Specifies a file to write the serialized data to. By default, the data goes to standard output. Can also be used like > output.json.

Example Usage

  • python manage.py dumpdata output.json --format json --database default Without specifying a model name — dumps the entire selected database.
  • python manage.py dumpdata auth output.json --format json --database default Dumps only the auth model.
  • python manage.py dumpdata auth.user output.json --format json --database default Dumps only the user section within the auth model.
  • python manage.py dumpdata --exclude admin output.json --format json --database default Dumps all data except admin.
  • python manage.py dumpdata mymodel output.json --format json --database myseconddb Dumps the data from the model named mymodel in the database named myseconddb (my second database).

Warning

If you get the RelatedObjectDoesNotExist error during the dumpdata command, check out this address: https://code.djangoproject.com/ticket/28972 and use it as python manage.py dumpdata -o output.json --format json — the problem will be resolved.

Loaddata

The loaddata command lets us load the data created with dumpdata into a newly created database. The source code address for loaddata is: loaddata.py

Usage

General usage: python manage.py loaddata fixture [fixture ...] where fixture is the file created with dumpdata.

Parameters

  • --database DATABASE Same as above — you can select a database. Defaults to the default database.
  • --ignorenonexistent, -i Allows ignoring fields and models that don’t exist.
  • --app APP_LABEL Allows loading a specific app.
  • --format FORMAT Enter the format of the file you created with dumpdata.
  • --exclude EXCLUDE, -e EXCLUDE Same purpose — used to exclude applications or models during loading.

Example Usage

  • python manage.py loaddata mydata.json --format json
  • python manage.py loaddata mydata.json --database mydb
  • python manage.py loaddata mydata.json --format xml --database default
  • python manage.py loaddata mydata.json --exclude auth --database default
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