I have working code -- I just want to make sure I'm doing this the best way. If I have a graph of related objects, spanning numerous tables and relationships, including many-to-many, and I want to eagerly load the entire graph (rooted in some selected row or rows of one of the tables) in a single query, I can do something like this:
(In this example, B and C have a many-to-many relationship containing extra fields on the relationship table, with BC as the association object. The other relationships are either one-to-many or many-to-one -- both seem to work the same way for this purpose.). session.query(A, B, BC, C, D, E).join(B, BC, C, D, E).filter(A.id==someId).options(contains_eager(A.b, B.bc, BC.c, C.d, D.e)) That seems to work. It gives me a big honkin' query with inner joins, returning a number of rows equal to the number of E's in the graph rooted at A.id==someId. Each row contains all columns of all the tables. In my particular application at least, it is faster to do it this way than to load each relation lazily, in the case where it's all going to be loaded anyway. My question is simply -- is there a better way? I chose contains_eager so that I could make the joins all inner joins, because in my case I don't need to worry about rows higher up in the chain that don't have corresponding rows further down. I suppose I could simplify my code -- presumably at the expense of execution time -- if I just used joinedload instead, and let SA make it a big outer join. It just seems like a rather verbose way to tell SA "please just eagerly follow all relationships as far as they lead you" -- is there a shortcut? -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
