Question

I’m trying to add has_many_through relationship through a form nested in a parent model. I can’t figure out if this is possible?

The nested form works ok without the checkboxes. And the checkboxes work fine when they’re outside the nested form.

= semantic_form_for @raduser do |f|
  %ul       
    %li
      = f.text_field :expiration, :placeholder => 'Expiration Date', :id => 'expiration_date'
    - f.fields_for :radcheck do |builder|
      = builder.text_field :username, :placeholder => 'Stuff'
      -Radgroup.all.each do |group|
        %li
          = check_box_tag 'radcheck[radgroup_ids]', group.id, @radcheck.radgroup_ids.include?(group.id)
          = group.groupname          

    %li
      = f.submit

This throws an error:

 undefined method `radgroup_ids' for #<ActiveRecord::Relation:0x007faaa24c2468>

I’ve got the models set up fine I think as all values save perfectly without the checkboxes

— EDIT ADDED MODELS —

Radusers have many Radcheck (singular due to legacy db). Radcheck has many radgroups through radusergroup.

class Raduser < ActiveRecord::Base

  has_many :radcheck, :dependent => :destroy
  accepts_nested_attributes_for :radcheck, :reject_if => lambda { |a| a[:value].blank? }, :allow_destroy => true   

end

class Radcheck < ActiveRecord::Base
  self.table_name = 'radcheck'

  attr_accessible :attribute_name, :username, :value, :op, :radgroupcheck_id, :radcheck_serial, :radgroup_ids

  belongs_to :raduser

  has_many :radusergroup, :dependent => :destroy
  has_many :radgroup, :through => :radusergroup

end

class Radgroup < ActiveRecord::Base
  self.table_name = 'radgroup'

  has_many :radusergroup, :dependent => :destroy
  has_many :radcheck, :through => :radusergroup

end


class Radusergroup < ActiveRecord::Base

belongs_to :radcheck
belongs_to :radgroup

end

— UPDATE TWO —

 def new
  @radcheck = Radcheck.new
  ...      
 end

 def create
  @radcheck = Radcheck.new(params[:radcheck])
  ...
 end

— UPDATE 3 —

My db currently looks like this:

 +----------------+-----------------------+----------+------+
 | radcheck_id    | radgroup_id           | priority | id   |
 +----------------+-----------------------+----------+------+
 | 8              | 3                     |        1 |    1 |
 | 4              | 9                     |        0 |    2 |
 | 22             | 4                     |        1 |    3 |
 | 2              | 6                     |        1 |    4 |

I have the solution suggested below working.

What I was hoping to do was insert the radcheck_username and radgroup_groupname into the db, not the radcheck_id:

+----------------+-----------------------+----------+------+
| ...username    | --groupname           | priority | id   |
+----------------+-----------------------+----------+------+
| user123344     | group88888            |        1 |    1 |
| shushQb        | 30-minutes            |        0 |    2 |
| forty          | gigiig                |        1 |    3 |
| snang          | ps-staff              |        1 |    4 |

Is this possible?

Answer 1

The problem appears to be that you’re trying to access Radcheck’s various Radgroups through a method that isn’t defined yet. I can see a couple of solutions to this. One would be to add the missing radgroup_ids method to your model. Alternatively, I think you could call include? on Radchecks radgroups relation.

Solution A

Within your Radcheck class, define:

def radgroup_ids
  radgroups.map(&:id)
end

Solution B

Make a minor change to the way you’re checking for included Radgroups

@radcheck.radgroups.include?(group)