Iterating over has_many objects with the :through association together

It is often the case when I iterate over an array of objects in a
has_many_through association that I want access to both the :has_many
objects and the :through objects. There is generally something in
that join object that is useful to get at, but enumerating with the
each method, I don't have easy access to that join object.

Example:

class User < ActiveRecord::Base
   has_many :memberships
   has_many :groups, :through => :memberships
end

# ugly way
user.groups.each do |group|
  membership = user.memberships.detect { |memberships|
memberships.group_id == group.id}
  # or
  membership = user.memberships.find(:first, :conditions =>
["memberships.group_id = ?", group.id]}
  puts "#{group.name}, #{membership.status}"
end

# a better way
user.groups.each_with_join do |group, membership|
  puts "#{group.name}, #{membership.status}"
end

I created a ticket with a patch (tested) in lighthouse:
http://rails.lighthouseapp.com/projects/8994/tickets/82-iterate-over-has_many-array-with-the-join-through-model

Let me know what you think!

Daniel

I was hoping this ticket could be resolved in time for 2.1, it's complete with tests that show the failure.

http://dev.rubyonrails.org/ticket/11565

But your ticket has nothing to do with the one I was proposing, so
let's not lump them together.

Sorry about that. Wasn't my intent.

It is often the case when I iterate over an array of objects in a
has_many_through association that I want access to both the :has_many
objects and the :through objects. There is generally something in
that join object that is useful to get at, but enumerating with the
each method, I don't have easy access to that join object.

Example:

class User < ActiveRecord::Base
   has_many :memberships
   has_many :groups, :through => :memberships
  end

# ugly way
user.groups.each do |group|
  membership = user.memberships.detect { |memberships|
memberships.group_id == group.id}
  # or
  membership = user.memberships.find(:first, :conditions =>
["memberships.group_id = ?", group.id]}
  puts "#{group.name}, #{membership.status}"
end

# a better way
user.groups.each_with_join do |group, membership|
  puts "#{group.name}, #{membership.status}"
end

This should really just be:

user.memberships.each do |membership|
  puts membership.status, membership.group.name
end

So I can't the need for this feature.