I'm stuck with the query that checks whether two arrays have one or more elements in common.
Since the query is the part of a much bigger query, I need to use Arel to accomplish this. But the && operator, known as the overlap operator, is not implemented in Arel gem.
There's a postgres_ext gem that implements the above mentioned operator and provides a .overlap method so that one could construct the query similar to the one I did: DiscountCondition.arel_table[:target_plan_period_ids].overlap(target_period_ids). This produces an SQL where clause that works fine for me: "\"discount_conditions\".\"target_plan_period_ids\" && '{2}'".
But. The thing is some tests in our application failed with the following error: NoMethodError: undefined method 'array' for #<ActiveRecord::ConnectionAdapters::SQLite3Column:0x007f23c4995ba8> (turns out the gem is incompatible with some adapters).
A simple ActiveRecord query that works is DiscountCondition.where('target_plan_period_ids && ARRAY[?]', target_period_ids) that produces the following SQL query "SELECT \"discount_conditions\".\"discount_id\" FROM \"discount_conditions\" WHERE (target_plan_period_ids && ARRAY[2])".
So, I wanted to know if anyone faced that issue and succeeded to workaround this.
Just in case someone ever faces the same issue, I ended up monkey patching the aforementioned functionality of a postgres_ext gem into the project.