Rails: HABTM association between ActiveResource and ActiveRecord class

Question

I am trying to implement my own methods for habtm association between ActiveResource and ActiveRecord classes in my Rails app.

Here is my classes:

   class Project < ActiveResource::Base
   end

   class Target < ActiveRecord::Base

   has_and_belongs_to_many :projects

   def project_ids
     project_ids
   end

  def project_ids=(pids)
    project_ids = pids
  end

  def projects
    projects = []
    pids = project_ids.split(",")
    pids.each do |pid|
      projects.push(Project.find(pid))
    end
  end

  def projects=(projs)
    pids = projs.collect(&:id)
    project_ids = pids.join(",")
  end
 end

I also have join table projects_targets with two columns project_id and target_id.

This does not record the association value into the join table upon creation.

My Questions:

1. Is there any other approach to do this ?
2. Am I missing something in my association methods?

I'd really appreciate any help.

Thanks in advance for help!

Answer 1

My advice is to not fight the framework and use the built in methods. If you wanted to implement custom accessors, then you should switch to a has many through because it will give you a model ( of the join table ) that you can work with to set the association manually.

Start here: http://edgeguides.rubyonrails.org/association_basics.html#the-has-and-belongs-to-many-association

You will not need the custom accessors project_ids or projects because rails will do the work magically.

You can easily do assignments like so:

some_target.projects << some_project

You don't even have to call some_target.save because the << operator is saving the association and writing the id's to the join table for you.

If you have an array of projects, or an active record relation ( like the result of a where clause) you can pass it in the same way

some_target.projects << array_of_projects

To remove the association, you can call destroy with an object like

some_target.projects.destroy a_specific_project

This won't destroy a_specific_project, but it will un-associate it.