Hello, I am having a problem where has_one would return the same id each time. Here is a rough example (simplified from my more complex application):

class Label
include Mongoid::Document
belongs_to :item
field :data
end

class Item
include Mongoid::Document
has_one :upc_label, :class_name => 'Label', :inverse_of => :item
has_one :nutritional_label, :class_name => 'Label', :inverse_of => :item
has_one :warning_label, :class_name => 'Label', :inverse_of => :item
field :name
end

I run the following:

1. Insert data
   item = Item.create(name: "Item1")

1. Insert labels
   upc = Label.create(data: "upc")
   nutritional = Label.create(data: "nutritional")
   warning = Label.create(data: "warning")

puts upc._id
> 53de0588737175687c060000

puts nutritional._id
> 53de0588737175687c070000

puts warning._id
> 53de0588737175687c080000

1. Save labels to item
   item.upc_label = upc
   item.nutritional_label = nutritional
   item.warning_label = warning
   item.save!

1. Now retrieve the item and print out label ids
   retrieved_item = Item.find(item._id)

puts retrieved_item.upc_label._id
> 53de0588737175687c080000

puts retrieved_item.nutritional_label._id
> 53de0588737175687c080000

puts retrieved_item.warning_label._id
> 53de0588737175687c080000

As you can see, even though the labels have different IDs, the item still returns the same label ID for each has_one. It looks like the last label (warning_label) overwrites all the other ones in the Item model.

I expected Item to have the different label ids, but that was not the case.

I am using:

• ruby 2.1.2p95
• mongoid (4.0.0)
• mongo 2.4.10