diff options
Diffstat (limited to 'django/db/models/fields/__init__.py')
| -rw-r--r-- | django/db/models/fields/__init__.py | 61 |
1 files changed, 59 insertions, 2 deletions
diff --git a/django/db/models/fields/__init__.py b/django/db/models/fields/__init__.py index 4416898d80..18b48c0e72 100644 --- a/django/db/models/fields/__init__.py +++ b/django/db/models/fields/__init__.py @@ -202,6 +202,7 @@ class Field(RegisterLookupMixin): validators=(), error_messages=None, db_comment=None, + db_default=NOT_PROVIDED, ): self.name = name self.verbose_name = verbose_name # May be set by set_attributes_from_name @@ -212,6 +213,13 @@ class Field(RegisterLookupMixin): self.remote_field = rel self.is_relation = self.remote_field is not None self.default = default + if db_default is not NOT_PROVIDED and not hasattr( + db_default, "resolve_expression" + ): + from django.db.models.expressions import Value + + db_default = Value(db_default) + self.db_default = db_default self.editable = editable self.serialize = serialize self.unique_for_date = unique_for_date @@ -263,6 +271,7 @@ class Field(RegisterLookupMixin): return [ *self._check_field_name(), *self._check_choices(), + *self._check_db_default(**kwargs), *self._check_db_index(), *self._check_db_comment(**kwargs), *self._check_null_allowed_for_primary_keys(), @@ -379,6 +388,39 @@ class Field(RegisterLookupMixin): ) ] + def _check_db_default(self, databases=None, **kwargs): + from django.db.models.expressions import Value + + if ( + self.db_default is NOT_PROVIDED + or isinstance(self.db_default, Value) + or databases is None + ): + return [] + errors = [] + for db in databases: + if not router.allow_migrate_model(db, self.model): + continue + connection = connections[db] + + if not getattr(self.db_default, "allowed_default", False) and ( + connection.features.supports_expression_defaults + ): + msg = f"{self.db_default} cannot be used in db_default." + errors.append(checks.Error(msg, obj=self, id="fields.E012")) + + if not ( + connection.features.supports_expression_defaults + or "supports_expression_defaults" + in self.model._meta.required_db_features + ): + msg = ( + f"{connection.display_name} does not support default database " + "values with expressions (db_default)." + ) + errors.append(checks.Error(msg, obj=self, id="fields.E011")) + return errors + def _check_db_index(self): if self.db_index not in (None, True, False): return [ @@ -558,6 +600,7 @@ class Field(RegisterLookupMixin): "null": False, "db_index": False, "default": NOT_PROVIDED, + "db_default": NOT_PROVIDED, "editable": True, "serialize": True, "unique_for_date": None, @@ -876,7 +919,10 @@ class Field(RegisterLookupMixin): @property def db_returning(self): """Private API intended only to be used by Django itself.""" - return False + return ( + self.db_default is not NOT_PROVIDED + and connection.features.can_return_columns_from_insert + ) def set_attributes_from_name(self, name): self.name = self.name or name @@ -929,7 +975,13 @@ class Field(RegisterLookupMixin): def pre_save(self, model_instance, add): """Return field's value just before saving.""" - return getattr(model_instance, self.attname) + value = getattr(model_instance, self.attname) + if not connection.features.supports_default_keyword_in_insert: + from django.db.models.expressions import DatabaseDefault + + if isinstance(value, DatabaseDefault): + return self.db_default + return value def get_prep_value(self, value): """Perform preliminary non-db specific value checks and conversions.""" @@ -968,6 +1020,11 @@ class Field(RegisterLookupMixin): return self.default return lambda: self.default + if self.db_default is not NOT_PROVIDED: + from django.db.models.expressions import DatabaseDefault + + return DatabaseDefault + if ( not self.empty_strings_allowed or self.null |