Question

I’m trying to create nested fields using mongodb. For that I’m using the gem mongomodel which allows work with ruby and mongodb and I’m using the gem nested_form, to create dynamics nested fields. I’m having the following trouble:

undefined methodreflect_on_association’ for #`

Other errors like it, that I have found in the internet doesn’t really match what I want to do here with mongodb. I’m new to RoR, and I don’t know how to solve this. Can anyone help me?

Here is my models:

survey.rb

class Survey < MongoModel::Document
  property :name, String
  property :questions, Collection[Question]
  timestamps!

  accepts_nested_attributes_for :questions, :reject_if => lambda { |a| a[:content].blank? }, :allow_destroy => true
end

questions.rb

class Question < MongoModel::Document
  property :content, String
  timestamps!
end

My controller:

surveys_controller.rb
class SurveysController < ApplicationController
  # GET /surveys
  # GET /surveys.json
  def index
    @surveys = Survey.all

    respond_to do |format|
      format.html # index.html.erb
      format.json { render json: @surveys }
    end
  end

  # GET /surveys/1
  # GET /surveys/1.json
  def show
    @survey = Survey.find(params[:id])

    respond_to do |format|
      format.html # show.html.erb
      format.json { render json: @survey }
    end
  end

  # GET /surveys/new
  # GET /surveys/new.json
  def new
    @survey = Survey.new

    respond_to do |format|
      format.html # new.html.erb
      format.json { render json: @survey }
    end
  end

  # GET /surveys/1/edit
  def edit
    @survey = Survey.find(params[:id])
  end

  # POST /surveys
  # POST /surveys.json
  def create
    @survey = Survey.new(params[:survey])

    respond_to do |format|
      if @survey.save
        format.html { redirect_to @survey, notice: 'Survey was successfully created.' }
        format.json { render json: @survey, status: :created, location: @survey }
      else
        format.html { render action: "new" }
        format.json { render json: @survey.errors, status: :unprocessable_entity }
      end
    end
  end

  # PUT /surveys/1
  # PUT /surveys/1.json
  def update
    @survey = Survey.find(params[:id])

    respond_to do |format|
      if @survey.update_attributes(params[:survey])
        format.html { redirect_to @survey, notice: 'Survey was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render action: "edit" }
        format.json { render json: @survey.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /surveys/1
  # DELETE /surveys/1.json
  def destroy
    @survey = Survey.find(params[:id])
    @survey.destroy

    respond_to do |format|
      format.html { redirect_to surveys_url }
      format.json { head :no_content }
    end
  end
end

My gemfile:

source 'https://rubygems.org'

gem 'rails', '3.2.8'

# Bundle edge Rails instead:
# gem 'rails', :git => 'git://github.com/rails/rails.git'

gem "mongomodel"
gem "bson_ext"
gem "nested_form"

# Gems used only for assets and not required
# in production environments by default.
group :assets do
  gem 'sass-rails',   '~> 3.2.3'
  gem 'coffee-rails', '~> 3.2.1'

  # See https://github.com/sstephenson/execjs#readme for more supported runtimes
  # gem 'therubyracer', :platforms => :ruby

  gem 'uglifier', '>= 1.0.3'
end

gem 'jquery-rails'

# To use ActiveModel has_secure_password
# gem 'bcrypt-ruby', '~> 3.0.0'

# To use Jbuilder templates for JSON
# gem 'jbuilder'

# Use unicorn as the app server
# gem 'unicorn'

# Deploy with Capistrano
# gem 'capistrano'

# To use debugger
# gem 'debugger'

My view of survey:

_form.html.erb
<%= nested_form_for(@survey) do |f| %>
  <% if @survey.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@survey.errors.count, "error") %> prohibited this survey from being saved:</h2>

      <ul>
      <% @survey.errors.full_messages.each do |msg| %>
        <li><%= msg %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div class="field">
    <%= f.label :name %><br />
    <%= f.text_field :name %>
  </div>
  <p>
    <%= f.fields_for :questions do |builder| %>
    <p>
        <%= builder.label :content, "Question" %>
    <%= builder.text_area :content, :rows => 3 %>
    </p>    
    <% end %>
    <p><%= f.link_to_add "Add a Question", :questions %></p>
  </p>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

Answer 1

I was trying to follow this railscast, but I wanted to work with mongodb, and I was using the gem mongomodel to do that. I wasn’t able to do what I wanted because I got the error described above, and even for the button “Remove” I got another error that I can’t remember now. Whatever, I really couldn’t do what I wanted using mongomodel, so I tried to do that using mongoid and everything was easier.