Method test_deferred_column_query

test/orm/test_merge.py:2061–2103

(self)

        )

    def test_deferred_column_query(self):
        Book, book = self.classes.Book, self.tables.book
        self.mapper_registry.map_imperatively(Book, book)
        sess = fixture_session()

        b = Book(
            id=1,
            title="Essential SQLAlchemy",
            summary="some summary",
            excerpt="some excerpt",
        )
        sess.add(b)
        sess.commit()

        # defer 'excerpt' at query level instead of mapping level
        b1 = sess.query(Book).options(defer(Book.excerpt)).first()
        sess.expire(b1, ["summary"])
        sess.close()

        def go():
            b2 = sess.merge(b1, load=False)

            # should not emit load for deferred 'excerpt'
            eq_(b2.summary, "some summary")
            not_in("excerpt", b2.__dict__)

            # now it should emit load for deferred 'excerpt'
            eq_(b2.excerpt, "some excerpt")
            in_("excerpt", b2.__dict__)

        self.sql_eq_(
            go,
            [
                (
                    "SELECT book.summary FROM book WHERE book.id = :pk_1",
                    {"pk_1": 1},
                ),
                (
                    "SELECT book.excerpt FROM book WHERE book.id = :pk_1",
                    {"pk_1": 1},
                ),
            ],
        )


class MutableMergeTest(fixtures.MappedTest):