How do I write a UNION chain with ActiveRelation?

Question

I need to be able to chain an arbitrary number of sub-selects with UNION using ActiveRelation.

I\'m a little confused by the ARel implementation of this, si

Answer 1

There's a way to make this work using arel:

tc=TestColumn.arel_table
return TestColumn.where(tc[:id]
           .in(TestColumn.select(:id)
                         .where(:attr1=>true)
                         .union(TestColumn.select(:id)
                                          .select(:id)
                                          .where(:attr2=>true))))