ruby on rails - Nested Forms for Embedded Documents -

i have following models

cities(id, name, geo {lng,lat})

geo(lng,lat)

cities model

class city   include mongoid::document   include mongoid::timestamps    field :name, type: string   field :timezone, type: string   field :slug, type: string    belongs_to :region   belongs_to :country    embeds_one :geo_location   accepts_nested_attributes_for :geo_location end 

geo locations model

class geolocation   include mongoid::document   include mongoid::timestamps    field :lng, type: string   field :lat, type: string    embedded_in :city end 

cities controller

class citiescontroller < applicationcontroller   before_action :set_city, only: [:show, :edit, :update, :destroy]    # /cities   def index     @cities = city.all   end    # /cities/1   def show   end    # /cities/new   def new     @city = city.new     @regions = region.all.asc(:name)     @countries = country.all.asc(:name)   end    # /cities/1/edit   def edit     @regions = region.all.asc(:name)     @countries = country.all.asc(:name)   end    # post /cities   def create     @city = city.new(city_params)      if @city.save       redirect_to @city, notice: 'city created.'     else       render action: 'new'     end   end    # patch/put /cities/1   def update     if @city.update(city_params)       redirect_to @city, notice: 'city updated.'     else       render action: 'edit'     end   end    # delete /cities/1   def destroy     @city.destroy     redirect_to cities_url, notice: 'city destroyed.'   end    private     # use callbacks share common setup or constraints between actions.     def set_city       @city = city.find(params[:id])     end      # allow trusted parameter "white list" through.     def city_params       params.require(:city).permit(:name, :timezone, :region_id, :country_id, :slug, :geo_locations_attributes => [:id, :lag, :lat])     end end 

form:

<%= form_for(@city) |f| %>   <% if @city.errors.any? %>     <div id="error_explanation">       <h2><%= pluralize(@city.errors.count, "error") %> prohibited city being saved:</h2>        <ul>       <% @city.errors.full_messages.each |msg| %>         <li><%= msg %></li>       <% end %>       </ul>     </div>   <% end %>    <div class="field">     <%= f.label :name %><br>     <%= f.text_field :name %>   </div>   <div class="field">     <%= f.label :country %><br>     <%= f.collection_select :country_id, @countries, :id, :name, :prompt => "please select" %>   </div>   <div class="field">     <%= f.label :region %><br>     <%= f.collection_select :region_id, @regions, :id, :name, :prompt => "please select" %>   </div>   <div class="field">     <%= f.label :timezone %><br>     <%= f.text_field :timezone %>   </div>   <div class="field">     <%= f.label :slug %><br>     <%= f.text_field :slug %>   </div>    <%= f.fields_for :geo_locations |geo_location| %>     <div class="field">       <%= geo_location.label :lag %><br>       <%= geo_location.text_field :lag %>     </div>     <div class="field">       <%= geo_location.label :lat %><br>       <%= geo_location.text_field :lat %>     </div>   <% end %>    <div class="actions">     <%= f.submit %>   </div> <% end %> 

new view

<h1>new city</h1>  <%= render 'form' %>  <%= link_to 'back', cities_path %> 

the error getting

unpermitted parameters: geo_location

on controller, replace city_params method this,

 def city_params   params.require(:city).permit(:name, :timezone, :region_id, :country_id, :slug, :geo_location_attributes => [:id, :lag, :lat]) end 

on view, replace "f.fields_for :geo_locations" "f.fields_for :geo_location"

problem in geo_locations_attributes. should geo_location_attributes one-to-one relationship.