How to reflect in the database a new belongs_to and has_many relationship in Ruby on Rails

I am new to rails (usually a python guy) and have just been trying to build a simple task manager application for fun. I am using Devise for authentication and have a single Task object I am trying to relate to a user. I have added the following to the Task model:

class Task < ActiveRecord::Base
belongs_to :user
end

and I have added the following in my User model for Devise:

class User < ActiveRecord::Base
has_many :tasks

<<normal Devise stuff>>
end

Whenever I added this information I then ran: rake db:migrate. It then gave me an error that the database field did not exist for user_id when I tried to do anything with it.

I am sure it is something rather simple that I am missing. Thanks for the help.

Adding a `belongs_to` (or any other) relationship to your model only tells active record that models are linked logically. This gives you access to methods like `task.user`. For this to actually work, the instances must be linked via database fields.

This is the step you're missing: you need to create a migration that will add a column to the Task table indicating which user it belongs to.

rails g migration AddUserIdToTasks user_id:integer

Note AddUserIdToTasks can be whatever name you want. It makes no difference. You can then open `db/migrations/add_user_to_tasks` and see what it does. Usually self.up will modify the database how you want it and self.down will do the opposite (so, in this case, remove the used_id).

Then to actually execute the SQL commands to alter the database table and schema, run

rake db:migrate

You need to generate a migration to add the foreign key first:

rails g migration AddUserIdToTasks user_id:integer

Then run `db:migrate`

And if you want the user to be able to reference the association as `user.dreams`, you need to add `:class_name => 'Task'` to the has_many line in the User model.

Your user class seems to be too dreamy to take care of it's tasks.

has_many :dreams // should be probably
has_many :tasks

Assuming that you tasks model has a user_id field, that is.