ruby on rails - Mongoid::Errors::MixedRelations in AnswersController#create -

getting following error msg while saving answer:

problem: referencing a(n) answer document user document via relational association not allowed since answer embedded. summary: in order access a(n) answer user reference need go through root document of answer. in simple case require mongoid store foreign key root, in more complex cases answer multiple levels deep key need stored each parent hierarchy. resolution: consider not embedding answer, or key storage , access in custom manner in application code.

above error due code @answer.user = current_user in answerscontroller.

i want save login username answer embaded in question.

deivse user model:

class user   include mongoid::document   has_many :questions   has_many :answers 

---

class question    include mongoid::document   include mongoid::timestamps   include mongoid::slug    field :title, type: string   slug :title    field :description, type: string   field :starred, type: boolean    validates :title, :presence => true, :length => { :minimum => 20, :allow_blank => false }    embeds_many :comments   embeds_many :answers    #validates_presence_of :comments    belongs_to :user  end 

---

class answer    include mongoid::document   include mongoid::timestamps    field :content, type: string    validates :content, :presence => true,  :allow_blank => false    embedded_in :question, :inverse_of => :answers    #validates_presence_of :comments    belongs_to :user  end 

---

class answerscontroller < applicationcontroller    def create     @question = question.find(params[:question_id])     @answer = @question.answers.create(params[:answer].permit(:answerer, :content))     @answer.user = current_user     redirect_to @question, :notice => "answer added!"   end end 

using rails 4, ruby 2.2.2, mongoid.

that's error message says.

your answer model embedded in question model. say, can perform "normal" queries on question documents, , not on models embedded in 1 (actually can, it's more difficult , somehow kills point of using embedded documents).

so can user given answer, not inverse, have declared in user model.

the simplest solution remove has_many :answers user model, if want retrieve list of answers given user, embedding models not best solution: should have relational models.

to make things clear, should write belongs_to :user, inverse_of: nil