Creating nested hash from nested active record results

Ruby
1

Hello,
I’m trying to find a very abstract and “one size fits all” for converting nested active record results to nested hashes. It’s easy, to do one level deep as such:


results_to_hash = Hash[ found_categories.map{ |c| [c.id, c.title]}]

But, when I try to add another collection to the mix, it completely borks and the results_to_hash only returns an empty hash IE:


results_to_hash = Hash[ found_categories.map{ |c| [c.id, c.title, c.categories]}]

Ultimately, I’d like it to be smart enough to detect if a model object contains a collection (IE: object.class.reflect_on_all_associations), and automatically convert those to hashes.

Any ideas?

Thanks,
Eric

2

I’d first reach for something like jbuilder for this and be explicit about what properties you want to include.

Another option is to include nested models in a method like to_json

found_categories.to_json(:include => :categories)

If it’s a tree structure you’re trying to build out I’d reach for a gem like ancestry to build the nested hash for you.

Hope it helps :slight_smile:

3

Just an FIY. This is the method I came up with:


   def self.active_record_to_array_of_hashes(array_collection, sub_collection_names=[])
     hashed_collection = []
     array_collection.each do |obj|   
       tmp_hash = ActiveSupport::JSON.decode(obj.to_json)
     
       #### hashify specified model association
       sub_collection_names.each do |name| 
         if(obj.class.reflections.keys.include?(name))
           tmp_hash[name] = ActiveSupport::JSON.decode(obj.send(name).to_json)
         end
       end
       hashed_collection << tmp_hash
     end
     return hashed_collection
   end