Question

I have two models with the following associations:

• A user has many projects.
• A project belongs to a user.

User model (user.rb):

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

Project model (project.rb):

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

Foreign key migration file:

class AddForeignKeyToUsers < ActiveRecord::Migration
  def change
    add_column :users, :user_id, :integer
  end
end

When I call <%= @user.projects %> I get this error message:

SQLite3::SQLException: no such column: projects.user_id: SELECT "projects".* FROM "projects"  WHERE "projects"."user_id" = 2

Answer 1

You added the foreign key to the wrong table. It should be in projects, not in users:

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

Since you are sticking to the convention, you don’t have to specify the foreign key in your Project model. This should be enough:

belongs_to :user