Question

I need to convert an embedded document onto its own collection, so it can be referenced from another collection.

Lets suppose I have a Parent that embeds many Childs.
I was thinking of something along this:

Parent.all.each do |p|
 p.childs.all.each do |c|
  c.raw_attributes['parent_id'] = p.id
 end
 p.save! #will save parent and cascade persist all childs onto their own coll
end

Is this an option? Ideally I would run this in a console and I would only change mongoid mappings from embed_* to has_*, so I wouldn’t need to change the rest of my code or use another collection as staging.

Answer 1

I think, the code should look more like this (didn’t test)

child_coll = Mongoid.database.collection('children')

Parent.all.each do |p|
  p.childs.all.each do |c|
    c.attributes['parent_id'] = p.id

    child_coll.insert c.attributes # save children to separate collection
  end

  p.childs = nil # remove embedded data
  p.save
end

After that, you can change your embeds_many to has_many and (hopefully) it should work well.