Question

I have 3 models/tables: User, Task, and TaskInstance. The Task table is like a master list of tasks, not coupled to any particular user, whereas the TaskInstance table contains records that indicate a user’s completion of a particular task. In other words, a TaskInstance has a User id, a Task id, and a status boolean. A User has many TaskInstances. Users do not share TaskInstances, they each have their own collection.

What I would like to happen when a user first signs up for an account on the website is for the User.task_instances field to be populated with a new TaskInstance for every Task that exists in the master list.

From what I’ve read, I think I have to do this using before_create, because that should update the User before it gets saved for the first time. So far I have:

class User < ActiveRecord::Base

    has_many :task_instances    

    before_create :populate_task_instances

    private

        def populate_task_instances
            #something here
        end
end

So far I’m unsure of what goes in the populate_task_instances method. How do I loop through every record in the Task table and create a TaskInstance for each, and then ensure that the collection of TaskInstances gets saved to the User’s task_instances field?

I understand this is pretty trivial but this is my first foray into Rails.

Answer 1

Here is one solution I think

def populate_task_instances
  self.task_instances = Task.all.map {|task| TaskInstance.new task_id: task.id}
end