Pluck associated model's attribute in Rails query

Question

In my rails app, collections have many projects, and projects have many steps.

I\'d like to grab all the ids of steps

Answer 1

Unfortunately, I don't think that we could do it through AR in a single query. You could do a nested query below to retrieve it in two queries to the database:

Step.includes(:projects)
    .where(projects: { id: Projects.includes(:collections)
    .where(collections: { id: @collections.id }).pluck(:id) } )
    .pluck(:id)