accessing an attr_writer on a nested attribute asset from a file uploaded via form

Question

I have the following model structure

class Asset < ActiveRecord::Base
  attr_writer :session_user_id
  ...
end

class Item < ActiveRecord::Base
  has_many :assets, :as => :assetable, :dependent => :destroy
  ...
end

and want to put the user_id in the value associated with an asset. I am having a problem associating a variable on an uploaded file. Here's the post'd data:

"assets_attributes"=>{"3"=>{"asset"=>#<ActionDispatch::Http::UploadedFile:0x007fd04dde17f8 @original_filename="nautugly.jpg",
@content_type="image/jpeg",
@headers="Content-Disposition: form-data; name=\"menu_item[assets_attributes][3][asset]\"; filename=\"nautugly.jpg\"\r\nContent-Type: image/jpeg\r\n",
@tempfile=#<File:/var/folders/94/slp2488s6nvgg8qq0g0p5c0m0000gn/T/RackMultipart20120323-51480-1lpa754>>,
"description"=>""},...

and want to access a session_user_id in Asset. In the items_controller, I have added:

params[:item][:assets_attributes].each_with_index do |value, key|
  value.each do |y|
   y.asset.session_user_id=12
  end

but I get error msg:

undefined method `asset' for "3":String

I feel like I've tried every variation. How to get this to work?

Answer 1

I'm guessing here but how about using values instead of each_with_index.

params[:item][:assets_attributes].values do |y|
  y.asset.session_user_id=12
end

Answer 2

So, there are a couple of things.

First, each_with_index called on a Hash will give you the object then the index. Since Hash defines each as an enumerable with two variables you will get key the value.

params[:item][:assets_attributes].each_with_index do |attr1, attr2|
  puts attr1 # ["3", {"asset" => "MyAsset!"}]
  puts attr2 # 0

  attr1.each do |value|
    puts value 
    # "3" on First Run
    # {"asset" => "MyAsset!"} on Second Run
  end
end

So if you just want to mess with the values then I suggest natedavisolds' approach. But that leads us to our second problem. Accessing a Hash; you need to do it using brackets[] not method calls.

All in all it should look something like this,

params[:item][:assets_attributes].values.each do |y|
  y[:session_user_id] = 12
end