checks.py 文件源码

def _check_prepopulated_fields_key(self, obj, model, field_name, label):
        """ Check a key of `prepopulated_fields` dictionary, i.e. check that it
        is a name of existing field and the field is one of the allowed types.
        """

        try:
            field = model._meta.get_field(field_name)
        except FieldDoesNotExist:
            return refer_to_missing_field(field=field_name, option=label,
                                          model=model, obj=obj, id='admin.E027')
        else:
            if isinstance(field, (models.DateTimeField, models.ForeignKey, models.ManyToManyField)):
                return [
                    checks.Error(
                        "The value of '%s' refers to '%s', which must not be a DateTimeField, "
                        "a ForeignKey, or a ManyToManyField." % (label, field_name),
                        obj=obj.__class__,
                        id='admin.E028',
                    )
                ]
            else:
                return []