The snippet enables decoupling model classes, associated with a ForeignKey, for the purpose of separating them into two databases. Looking at the following example:
class Reporter(models.Model):
...
class Article(models.Model):
reporter = models.ForeignKey(Reporter)
We want to separate the `Reporter` and `Article` into two separate databases, but this won't work in Django because of the [cross model relations](http://docs.djangoproject.com/en/dev/topics/db/multi-db/#cross-database-relations). The solution is to use an ID field and not a `ForeignKey` one. This makes the access very uncomfortable. The above class will make this a bit less awkward. It doesn't support the [RelatedManager](http://docs.djangoproject.com/en/dev/ref/models/relations/#django.db.models.fields.related.RelatedManager), but it will support accessing the related field as you normally would.
The article class will look like this (assuming the reporter model id field is an `IntegerField`):
class Article(DecoupledModel):
reporter_id = models.IntegerField()
_linked_fields = {
'reporter': Reporter,
}
Once you have an article object, you can access the reporter as you normally would for both read and writing. For example:
my_reporter = article1.reporter
article2.reporter = my_reporter
The code was placed inside a helper file without using a class. The Django validator was not designed to work with validator classes, it would appear, so retrieving the value from the field proved to be a hassle. Just create a helper file, import it on your model, and use the validator in the standard way, as such:
cnpj = models.CharField(unique=True, max_length=14, validators=[validate_CNPJ])
cpf = models.CharField(unique=True, max_length=14, validators=[validate_CPF])
- model
- validation
- cnpj
- cpf