Rails combobox issue with has_many :through relationship

Question

Please help me to figure out the problem. My problem scenario is i have two model say user and project with has many through relationship.

Now i want to create a new user and assign the user with one or more project while creating the user.The project name will be choosen from a dropdown list in the users/_form.html.erb which will be populated from Project model. i want to save the data while creating the new user like this in the projectsusers database table: project_id user_id 1 1 2 1 3 1

when i am creating the new user i get this error "Couldn't find Project with ID=1 for User with ID= "

code

class User < ActiveRecord::Base
  attr_accessible :name, :projects_attributes
  has_many :project_users, :class_name => 'Projectuser'
  has_many :projects, through: :project_users
  accepts_nested_attributes_for :projects, :allow_destroy => true
end


class Project < ActiveRecord::Base
  attr_accessible :name
  has_many :project_users
  has_many :users, :through => :project_users

end


class Projectuser < ActiveRecord::Base
  attr_accessible :project_id, :user_id
  belongs_to :user
  belongs_to :project
end

 controller
   class UsersController < ApplicationController

# GET /users # GET /users.json def index @users = User.all

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

end

# GET /users/1 # GET /users/1.json def show @user = User.find(params[:id])

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

end

# GET /users/new # GET /users/new.json def new @user = User.new

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

end

# GET /users/1/edit def edit @user = User.find(params[:id]) end

# POST /users # POST /users.json def create @user = User.new(params[:user])

@user.project_users.build
respond_to do |format|
  if @user.save

    #@user.project_users.update_attributes(params[][:projects_attributes])
    format.html { redirect_to @user, notice: 'User was successfully created.' }
    format.json { render json: @user, status: :created, location: @user }
  else
    format.html { render action: "new" }
    format.json { render json: @user.errors, status: :unprocessable_entity }
  end
end

end

# PUT /users/1 # PUT /users/1.json def update @user = User.find(params[:id])

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

end

# DELETE /users/1 # DELETE /users/1.json def destroy @user = User.find(params[:id]) @user.destroy

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

end end

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

      <ul>
      <% @user.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>

  <div>
  <%= f.fields_for :projects do |task_form| %>
    <%= task_form.collection_select(:id, Project.all, :id, :name, :include_blank => true ) %>
    <%= task_form.link_to_remove "Remove this task" %>
  <% end %>
  <p><%= f.link_to_add "Add a task", :projects %></p>
  </div>
  <div class="actions">
  <%= f.submit %>
  </div>
<% end %>

error log :

Started POST "/users" for 127.0.0.1 at 2013-10-02 16:10:25 +0600 Processing by UsersController#create as HTML Parameters: {"utf8"=>"✓", "authenticity_token"=>"nCsy6E1MuAoMK7hGwAcMNJFVvmq60Bz75lqLLECxb/U=", "user"=>{"name"=>"talha", "projects_attributes"=>{"1380708606908"=>{"id"=>"1", "_destroy"=>"false"}}}, "commit"=>"Create User"} Project Load (0.1ms) SELECT "projects".* FROM "projects" INNER JOIN "projectusers" ON "projects"."id" = "projectusers"."project_id" WHERE "projectusers"."user_id" IS NULL AND "projects"."id" IN (1) Completed 404 Not Found in 32ms

ActiveRecord::RecordNotFound (Couldn't find Project with ID=1 for User with ID=): app/controllers/users_controller.rb:43:in new' app/controllers/users_controller.rb:43:increate'

Rendered /Users/maruf/.rvm/gems/ruby-1.9.3-p429/gems/actionpack-3.2.13/lib/action_dispatch/middleware/templates/rescues/_trace.erb (1.1ms) Rendered /Users/maruf/.rvm/gems/ruby-1.9.3-p429/gems/actionpack-3.2.13/lib/action_dispatch/middleware/templates/rescues/_request_and_response.erb (0.9ms) Rendered /Users/maruf/.rvm/gems/ruby-1.9.3-p429/gems/actionpack-3.2.13/lib/action_dispatch/middleware/templates/rescues/diagnostics.erb within rescues/layout (7.1ms)

Thanks in advance guys.........

Answer 1

I have changed the accepts_nested_attributes_for :project_users in the user model and the in the form I used task_form.collection_select(:project_id, Project.all, :id, :name, :multiple => true ) and it rocks.yey......