Question

I have a many-to-many relationship through a join table. This join table has an additional field, an integer.

Now for filtering purposes, I want to add an attribute to one of the models reflecting the sum of this additional field for the associated entries.

I’ve tried stuff like:

has "SUM(<join_table_name.field_name>)", :as => :availability, :type => :int

But this just yields errors like “nil is not a symbol” when running rake ts:rebuild. I assume I’m just doing it wrong, so before I add a lot of unnecessary additional info, I thought I’d see if someone knows the correct way to do this?

Answer 1

I think you’re almost there – but first, it’s :integer, not :int – and secondly, if the join is not being referred to normally by any other fields or attributes, then you need to ensure it’s part of the query:

join join_assoc

Beyond that, it’s all looking fine.