On Oct 17, 2013, at 11:21 AM, Chris <christoph.reisb...@gmail.com> wrote:
> They both have to be subqueries because they can have where-statements. > If select_from() is the normal way than I have to live with these additional > select-from-constructions. > > Do you have/know some example of how to use from_statement()? > Because I tried it with from_statement() but it doesn't work. > > > combined_query = > session.query(existing_query).join(additional_query).subquery() > session.query(TableOne).from_statement(combined_query.statement) > > --> raises NoSuchColumnError: "Could not locate column in row for column > 'table_one.id' I'm able to get a pretty clean statement by applying the join after the select_entity_from() (note that select_entity_from and select_from are the same in 0.8, but in 0.9 you'll want to use select_entity_from()): q1 = sess.query(A).subquery() q2 = sess.query(B).subquery() sess.query(A).select_entity_from(q1).join(q2).all() output: SELECT anon_1.id AS anon_1_id FROM (SELECT a.id AS id FROM a) AS anon_1 JOIN (SELECT b.id AS id, b.a_id AS a_id FROM b) AS anon_2 ON anon_1.id = anon_2.a_id > > By the way is there a way to retrieve the given class from a query object. > From example: > If a method create a Query object like this: > query = session.query(TableOne, TableTwo).filter(...) > and returns 'query'. > How can I find out that the query was created with the objects TableOne and > TableTwo ? Query has an accessor "column_descriptions" : http://docs.sqlalchemy.org/en/rel_0_8/orm/query.html?highlight=column_descriptions#sqlalchemy.orm.query.Query.column_descriptions
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