Rails 3: Retrieve all child records where parent model attribute equals search key

Question

I want to do a query that returns only the assets that do not have a serial number where the workorder branch equals a number.

class Workorder < ActiveRecor         


        

Answer 1

The query you would want to do is

Asset.joins(:workorder).where('workorders.branch = 325')

So you can make a scope like this:

scope :with_workorder_branch, lambda { |branch| joins(:workorder).where('workorders.branch = ?', branch) }

If you're going to be looping through the workorders, you should change the joins to includes as this eager loads them.

The rails guide to queries is very helpful for this sort of thing http://guides.rubyonrails.org/active_record_querying.html