How to provide initial data for models¶
It’s sometimes useful to prepopulate your database with hard-coded data when you’re first setting up an app. You can provide initial data with migrations or fixtures.
Provide initial data with migrations¶
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.
Provide data with fixtures¶
You can also provide data using fixtures,
however, this data isn’t loaded automatically, except if you use
TransactionTestCase.fixtures.
Uma fixture é uma coleção de dados que o Django sabe como importar para o banco de dados. A maneira mais fácil de criar uma “fixture” se você já tem algum dado é usar o comando manage.py dumpdata. Ou, você pode escrever fixtures manualmente; “fixtures” podem ser escritas como documentos JSON, XML ou YAML (com PyYAML installed). O documentos de serialização tem mais detalhes sobre cada um destes formatos de serialização.
As an example, though, here’s what a fixture for a 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"
}
}
]
E aqui a mesma “fixture” como 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
Você armazenará este dado em um diretório fixtures dentro de sua app.
You can load data by calling 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 reloaded 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.
Tell Django where to look for fixture files¶
By default, Django looks for fixtures in the fixtures directory inside each
app, so the command loaddata sample will find the file
my_app/fixtures/sample.json. This works with relative paths as well, so
loaddata my_app/sample will find the file
my_app/fixtures/my_app/sample.json.
Django also looks for fixtures in the list of directories provided in the
FIXTURE_DIRS setting.
To completely prevent default search from happening, use an absolute path to
specify the location of your fixture file, e.g. loaddata /path/to/sample.
Namespace your fixture files
Django will use the first fixture file it finds whose name matches, so if
you have fixture files with the same name in different applications, you
will be unable to distinguish between them in your loaddata commands.
The easiest way to avoid this problem is by namespacing your fixture
files. That is, by putting them inside a directory named for their
application, as in the relative path example above.
Ver também
As “Fixtures” são também usadas pelo testing framework para auxiliar na configuração de um ambiente de teste consistente.
