Python django.db.connection.features() Examples

def _should_check_constraints(self, connection):
        return (
            connection.features.can_defer_constraint_checks and
            not connection.needs_rollback and connection.is_usable()
        ) 

def skipIfDBFeature(*features):
    """
    Skip a test if a database has at least one of the named features.
    """
    return _deferredSkip(
        lambda: any(getattr(connection.features, feature, False) for feature in features),
        "Database has feature(s) %s" % ", ".join(features)
    ) 

def skipUnlessAnyDBFeature(*features):
    """
    Skip a test unless a database has any of the named features.
    """
    return _deferredSkip(
        lambda: not any(getattr(connection.features, feature, False) for feature in features),
        "Database doesn't support any of the feature(s): %s" % ", ".join(features)
    ) 

def can_migrate(self, connection):
        """
        Return True if the model can/should be migrated on the `connection`.
        `connection` can be either a real connection or a connection alias.
        """
        if self.proxy or self.swapped or not self.managed:
            return False
        if isinstance(connection, six.string_types):
            connection = connections[connection]
        if self.required_db_vendor:
            return self.required_db_vendor == connection.vendor
        if self.required_db_features:
            return all(getattr(connection.features, feat, False)
                       for feat in self.required_db_features)
        return True 

def _reset_sequences(self, db_name):
        conn = connections[db_name]
        if conn.features.supports_sequence_reset:
            sql_list = conn.ops.sequence_reset_by_name_sql(
                no_style(), conn.introspection.sequence_list())
            if sql_list:
                with transaction.atomic(using=db_name):
                    cursor = conn.cursor()
                    for sql in sql_list:
                        cursor.execute(sql) 

def connections_support_transactions():
    """
    Returns True if all connections support transactions.
    """
    return all(conn.features.supports_transactions
               for conn in connections.all()) 

def skipIfDBFeature(*features):
    """
    Skip a test if a database has at least one of the named features.
    """
    return _deferredSkip(
        lambda: any(getattr(connection.features, feature, False) for feature in features),
        "Database has feature(s) %s" % ", ".join(features)
    ) 

def skipUnlessDBFeature(*features):
    """
    Skip a test unless a database has all the named features.
    """
    return _deferredSkip(
        lambda: not all(getattr(connection.features, feature, False) for feature in features),
        "Database doesn't support feature(s): %s" % ", ".join(features)
    ) 

def can_migrate(self, connection):
        """
        Return True if the model can/should be migrated on the `connection`.
        `connection` can be either a real connection or a connection alias.
        """
        if self.proxy or self.swapped or not self.managed:
            return False
        if isinstance(connection, six.string_types):
            connection = connections[connection]
        if self.required_db_vendor:
            return self.required_db_vendor == connection.vendor
        if self.required_db_features:
            return all(getattr(connection.features, feat, False)
                       for feat in self.required_db_features)
        return True 

def _reset_sequences(self, db_name):
        conn = connections[db_name]
        if conn.features.supports_sequence_reset:
            sql_list = conn.ops.sequence_reset_by_name_sql(
                no_style(), conn.introspection.sequence_list())
            if sql_list:
                with transaction.atomic(using=db_name):
                    cursor = conn.cursor()
                    for sql in sql_list:
                        cursor.execute(sql) 

def connections_support_transactions():
    """
    Returns True if all connections support transactions.
    """
    return all(conn.features.supports_transactions
               for conn in connections.all()) 

def _should_check_constraints(self, connection):
        return (
            connection.features.can_defer_constraint_checks and
            not connection.needs_rollback and connection.is_usable()
        ) 

def skipIfDBFeature(*features):
    """
    Skip a test if a database has at least one of the named features.
    """
    return _deferredSkip(
        lambda: any(getattr(connection.features, feature, False) for feature in features),
        "Database has feature(s) %s" % ", ".join(features)
    ) 

def skipUnlessAnyDBFeature(*features):
    """
    Skip a test unless a database has any of the named features.
    """
    return _deferredSkip(
        lambda: not any(getattr(connection.features, feature, False) for feature in features),
        "Database doesn't support any of the feature(s): %s" % ", ".join(features)
    ) 

def test_nonexistent_feature(self):
        self.assertFalse(hasattr(connection.features, 'nonexistent')) 

def test_mysql_supports_transactions(self):
        """
        All storage engines except MyISAM support transactions.
        """
        with mock.patch('django.db.connection.features._mysql_storage_engine', 'InnoDB'):
            self.assertTrue(connection.features.supports_transactions)
        del connection.features.supports_transactions
        with mock.patch('django.db.connection.features._mysql_storage_engine', 'MyISAM'):
            self.assertFalse(connection.features.supports_transactions)
        del connection.features.supports_transactions 

def test_nonexistent_feature(self):
        self.assertFalse(hasattr(connection.features, 'nonexistent')) 

def test_count_join_optimization_disabled(self):
        with mock.patch.object(connection.features, 'supports_foreign_keys', False), \
                CaptureQueriesContext(connection) as query:
            self.article.publications.count()
        self.assertIn('JOIN', query[0]['sql']) 

def test_exists_join_optimization_disabled(self):
        with mock.patch.object(connection.features, 'supports_foreign_keys', False), \
                CaptureQueriesContext(connection) as query:
            self.article.publications.exists()
        self.assertIn('JOIN', query[0]['sql']) 

def test_nullable_primary_key(self):
        class Model(models.Model):
            field = models.IntegerField(primary_key=True, null=True)

        field = Model._meta.get_field('field')
        with mock.patch.object(connection.features, 'interprets_empty_strings_as_nulls', False):
            results = field.check()
        self.assertEqual(results, [
            Error(
                'Primary keys must not have null=True.',
                hint='Set null=False on the field, or remove primary_key=True argument.',
                obj=field,
                id='fields.E007',
            ),
        ]) 

def test_nonexistent_feature(self):
        self.assertFalse(hasattr(connection.features, 'nonexistent')) 

def test_mock_django_connection(self, mock_handler):
        is_foo_before = bool(getattr(connection.features, 'is_foo', False))

        mock_django_connection(disabled_features=['is_foo'])

        is_foo_after = bool(getattr(connection.features, 'is_foo', False))

        self.assertTrue(is_foo_before)
        self.assertFalse(is_foo_after)


# noinspection PyUnresolvedReferences,PyStatementEffect 

def connections_support_transactions():
    """
    Returns True if all connections support transactions.
    """
    return all(conn.features.supports_transactions
               for conn in connections.all()) 

def skipIfDBFeature(*features):
    """
    Skip a test if a database has at least one of the named features.
    """
    return _deferredSkip(
        lambda: any(getattr(connection.features, feature, False) for feature in features),
        "Database has feature(s) %s" % ", ".join(features)
    ) 

def skipUnlessDBFeature(*features):
    """
    Skip a test unless a database has all the named features.
    """
    return _deferredSkip(
        lambda: not all(getattr(connection.features, feature, False) for feature in features),
        "Database doesn't support feature(s): %s" % ", ".join(features)
    ) 

def can_migrate(self, connection):
        """
        Return True if the model can/should be migrated on the `connection`.
        `connection` can be either a real connection or a connection alias.
        """
        if self.proxy or self.swapped or not self.managed:
            return False
        if isinstance(connection, str):
            connection = connections[connection]
        if self.required_db_vendor:
            return self.required_db_vendor == connection.vendor
        if self.required_db_features:
            return all(getattr(connection.features, feat, False)
                       for feat in self.required_db_features)
        return True 

def _reset_sequences(self, db_name):
        conn = connections[db_name]
        if conn.features.supports_sequence_reset:
            sql_list = conn.ops.sequence_reset_by_name_sql(
                no_style(), conn.introspection.sequence_list())
            if sql_list:
                with transaction.atomic(using=db_name):
                    cursor = conn.cursor()
                    for sql in sql_list:
                        cursor.execute(sql) 

def connections_support_transactions():
    """Return True if all connections support transactions."""
    return all(conn.features.supports_transactions for conn in connections.all()) 

def _should_check_constraints(self, connection):
        return (
            connection.features.can_defer_constraint_checks and
            not connection.needs_rollback and connection.is_usable()
        ) 

def skipIfDBFeature(*features):
    """Skip a test if a database has at least one of the named features."""
    return _deferredSkip(
        lambda: any(getattr(connection.features, feature, False) for feature in features),
        "Database has feature(s) %s" % ", ".join(features)
    )