nested embeds_many doesn't work

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    • Type: Task
    • Resolution: Done
    • Priority: Major - P3
    • 5.0.1
    • Affects Version/s: None
    • Component/s: None
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      We have

          class User
      include Mongoid::Document
      # some fields
      embeds_many :conversations
      accepts_nested_attribute_for :conversations
    end
    class Conversation
      include Mongoid::Document
      # some fields
      embedded_in :user
      embeds_many :messages
      accepts_nested_attribute_for :messages
    end
    class Message
      include Mongoid::Document
      field :message, type: String
      # some fields
      embedded_in :conversation
    end

      Now we create a user that has 2 conversations each with 2 messages

          u = User.create!
    c1 = u.conversations.create!
    c1.messages.create!(message: "one")
    c1.messages.create!(message: "two")
    c2 = u.conversations.create!
    c2.messages.create!(message: "three")
    c2.messages.create!(message: "four")

      Then, we need to change the message "two" with "six",

        
    u = User.last
    c1 = u.conversations.first
    m2 = c1.messages.last
    m2.message = "six"
    m2.save!
    m2.valid? # => true

      After all of this, why is it that it is not message "two" that is updated to "six", instead, it is "one" that now becomes "six" and "two" remains as "two"

      I noticed that the update part of the code produces this following Moped update query : 

      selector={"_id"=>BSON::ObjectId('539e4ec04db79b997d00000c'), "conversations._id"=>BSON::ObjectId('539e6c254db79b84ab00000d'), "conversatoins.0.messages._id"=>BSON::ObjectId('539fac734db79b1e4100000f')} update={"$set"=>{"conversations.0.messages.$.message"=>"six"}}

      I have tried to translate this MOPED syntax to javascript and tested it in mongo shell, that produced the same behavior. Then I realized that in MongoDB, positional operator "$" cannot be used to locate inner array.

      The question is, if Core MongoDB does not serve locating inner array element index using "$" (positional operator), why does Mongoid produce this query on nested embeds_many (nested MongoDB arrays)? Why not just makes a class that has embeds_many and embedded_in at the same time as invalid?

      Note: To test this I used Mongoid 4.0.0 rc1 and for the mongo shell, the version is 2.6.2

            Assignee:
            Dianna Hohensee (Inactive)
            Reporter:
            yudho
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              Created:
              Updated:
              Resolved: