Question

I have a form from which a project is created. The form collects data for two tables; ‘projects’ and ‘projects_users’. The last one
is a relational tabel which is used for storing which users that are members of the project (choosen in the form).

Creating a new project works fine, but when it comes to creating new posts in ‘projects_users’ it fails:

uninitialized constant ProjectsController::Projects_users

First of all, am I thinking in the right way (see the code below)?

What I do is that I extract the members array from params[:project], that’s retrieved from the form. Then I’m creating the project in the db, and when that is done I iterate through the members array (which contains of user_id’s) and creates the posts in the db for ‘projects_users’.

What am I doing wrong? Is there a better way to achieve what I want?

projects controller:

class ProjectsController < ApplicationController
def new
  @project = Project.new
  @users = (current_user.blank? ? User.all : User.find(:all, :conditions => ["id != ?", current_user.id]))
end

def create
  @members = params[:project].delete(:members)
  @project = Project.new(params[:project].merge(:user_id => current_user.id))

  if @project.save
    @members.each do |member|
        @project_members = Projects_users.new
        @project_members.project_id = @project.project_id
        @project_members.user_id = member.user_id
    end

    redirect_to @project
  else
    @users = (current_user.blank? ? User.all : User.find(:all, :conditions => ["id != ?", current_user.id]))
    render :new
  end
end
end

new.html.erb:

<%= form_for @project do |f| %>
<div class="alert alert-block">  
    <%= f.error_messages %>
</div>
<div class="text_field">
    <%= f.label :title%>
    <%= f.text_field :title%>
</div>
<div class="text_field">
    <%= f.label :description%>
    <%= f.text_field :description%>
</div>
<div class="dropdown">
    <%= f.label :start_date%>
    <%= f.date_select :start_date %>
</div>
<div class="dropdown">
    <%= f.label :end_date%>
    <%= f.date_select :end_date %>
</div><br/>
<span class="help-block">Välj användare som ska ingå ingå i projektet.</span>
<div class="checkbox">
    <% @users.each do |user| %>
        <%= check_box_tag "project[members][]", user.id, '1', :id => "user_#{user.id}" %> 
        <%= label_tag "user_#{user.id}", user.first_name + ' ' + user.last_name, :class => "checkbox" %>
    <% end %>
</div>
</div>
<div class="submit">
    <%= f.submit "Spara" %>
</div>
<% end %>

project model:

class Project < ActiveRecord::Base
  has_and_belongs_to_many :users, :class_name => 'User'

  belongs_to :user
  has_many :tickets, :dependent => :destroy

  // validation...

  # Setup accessible (or protected) attributes for your model
  attr_accessible :user_id, :title, :description, :start_date, :end_date
end

users model:

class User < ActiveRecord::Base
  attr_accessible :first_name, :last_name, :email, :password

  has_and_belongs_to_many :projects
  has_many :tickets

  ... other code

end

projects_users table:

project_id
user_id

projects table:

user_id (the user that creates the project = admin)
title
description
start_date
end_date

Answer 1

In the controller you are using Projects_users.new that means the new method for Projects_users model and as you are using HABTM association the join model doesn’t exist. If you want to use the join/associated model then you must use has_many :through association. But in case you just want to associate preexisting users to projects you can do it following way

@project.user_ids = @members

OR

@members.each do |member|
  user = User.find(member)
  @project.users << user
end

@member will be an array in your case not a hash. It will contain all the checked users’ ids. So you don’t need to have member.user_id as it is not a hash.