Nested queries in Arel

Question

I am attempting to nest SELECT queries in Arel and/or Active Record in Rails 3 to generate the following SQL statement.

SELECT sorted.* FROM (SELECT * FROM p         


        

Answer 1

Here's my approach to temporary tables and Arel. It uses Arel#from method passing in the inner query with Arel#to_sql.

inner_query = YourModel.where(:stuff => "foo")
outer_query = YourModel.scoped  # cheating, need an ActiveRelation
outer_query = outer_query.from(Arel.sql("(#{inner_query.to_sql}) as results")).
                          select("*")

Now you can do some nice things with the outer_query, paginate, select, group, etc...

inner_query ->

select * from your_models where stuff='foo'

outer_query ->

select * from (select * from your_models where stuff='foo') as results;