Question

Here are my associations:

• As user has many projects
• A project belongs to one user

User model (user.rb)

  class User < ActiveRecord::Base
     has_many :projects
     attr_accessible: :available, :department, :name, :skills, :title, :photo
  end

Project modal (project.rb)

  class Project < ActiveRecord::Base
     belongs_to :user, :foreign_key => :user_id
     attr_accessible :project_name
  end

Here’s the code in my show.erb.html file

  <%= @user.projects.each do |project| %>
    <p><%= projects.project_name %></p>
  <% end %>

But this just displays two brackets like this “[]”. Which makes me think it’s an empty array.

So when I run Project.find(1) in rails console to see if the project is being associated with the user, it spits out this:

   => #<Project id: 2, project_name: "This is a project. ", created_at: "2012-11-12 02:29:28", updated_at: "2012-11-12 02:29:28", user_id: nil> 

User id nil? What gives?!

Anyone know what I’m doing wrong? Thank you!

EDIT:

Here is the migration adding the foreign key:

  class AddForeignKeyToProjects < ActiveRecord::Migration
    def change
      add_column :projects, :user_id, :integer
    end
  end

EDIT 2

Here is the instances in the controllers (this is probably the problem)

Project controller

  def new
    @project = Project.new(params[:project], params[:user_id])   
  end

User controller

  def show
    @user = User.find(params[:id], params[:project_name])

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

Answer 1

If you used convention name, it means you had a user_id in Project table, you don’t need to specify foreign_key in Project model, you just need:

belongs_to :user

I don’t sure if this is your typo:

<%= projects.project_name %> should be <%= project.project_name %>

About your controller, I suppose you have current_user method, which define current user logged in. So if you want to create new project with user_id associated with current_user’s id, you should write this code:

def new
  @project = current_user.projects.build # Create new project with user_id = current_user.id
end

If you want to create new project, your create action will like this:

def create
  @project = current_user.projects.create(params[:project])

  if @project.save # save project success
    # do some thing
  else
    # do some thing
  end
end

Those are basic actions I can show you, because I don’t know how you build form, and how your route look like.

When you show a user, if you used RESTful routes, your route will look like this:

`abc.com/users/:id/show`

What is RESTful routes? If you want to know you should check this Recource routing.

Then, if you want to find a user, you could use params[:id]:

def show
  @user = User.find(params[:id])
  respond_to do |format|
    format.html # show.html.erb
    format.json { render json: @user }
  end
end

You can not find a user with params[:project_name], your user model don’t have that attribute, it’s attribute of project.