CODEWITHSUNDEEP
ruby-on-railsruby-on-rails-3.2
Rafael Muñoz Lattion
Rafael Muñoz Lattion

Reputation: 13

Rails collection_select many to many

I have a form with two collection_select fields, the first one is an easy one, it just gets a model named courses, which shows the course name, and of course returns the id of the selected course, the second is the one Im having problems with, its a collection_select of the similar courses a course may have.

The courses model:

class Course < ActiveRecord::Base
  extend FriendlyId
  friendly_id :name, use: :slugged 
  attr_accessible :code, :credits, :name, :description, :active

  has_many :similars, dependent: :destroy
  has_many :similar_courses, through: :similars, source: :similar

end

The similar model: 

class Similar < ActiveRecord::Base
  attr_accessible :course_id, :similar_id

  belongs_to :course
  belongs_to :similar, class_name: "Course"

  validates :similar_id, presence: true
  validates :course_id, presence: true

end

this is the homologate model, the thing with this model is that a course must be approved or rejected if one wants to transfer classes and stuff like that:

class Homologation < ActiveRecord::Base
  attr_accessible :homologate_by, :homologate_course, :student_id
  belongs_to :user
end

this is the form Im having problems with:

<%= form_for(@homologation) do |f| %>
      <%= render 'shared/error_messages', object: @homologation %>
      <%= f.label :homologate_course %>
      <%= f.collection_select :homologate_course, Course.find(:all), :id, :name, :prompt => "Select a Course" %>

      <%= f.label :homologate_by %>
      <%= f.collection_select :homologate_by, Similar.find(:all), :similar_id, :name, :prompt => "Select a Similar Course" %>
    <div class="form-actions">
      <%= f.submit "Create Homologation", class: "btn btn-large btn-primary" %>
    </div>
    <% end %>
  </div>

Im getting the following error

http://dpaste.com/hold/827744/

the Bartolleti thing is the name of the course I want to be able to show, and that of course is not a method, but I dont know Why Im getting the error, I want to be able to show the names of the similar courses given the first collection field course...

Thank you for your help!

Upvotes: 1

Views: 1117

Answers (3)

Adrien Coquio
Adrien Coquio

Reputation: 4930

From the doc of collection_select :

collection_select(object, method, collection, value_method, text_method, options = {}, html_options = {})

Then with your code you have Course.find(Similar.find_by_id(:similar_id)).name as the text_method, that is why you get this error message.

One solution could be to add a method on your Similar model to get the similar course name : 

def similar_name
  similar.name
end

then you can use it as the text_method in your collection_select :

<%= f.collection_select :homologate_by, Similar.find(:all), :similar_id, :similar_name, :prompt => "Select a Similar Course" %>

Upvotes: 0

vijikumar
vijikumar

Reputation: 1815

Here the problem is ,

        <%= f.collection_select :homologate_by, Similar.find(:all), :similar_id, :name, :prompt => "Select a Similar Course" %>

          In this line :name is trying to find a record from course and the course name.

So, it better to write Similar.find(:all) in the controller.

Upvotes: 0

Mike Waldrup
Mike Waldrup

Reputation: 757

First, I'd recommend taking your "Similar" logic out of the form. So do your find.all on it in the controller and use it in your view as an instance variable @similar_list or so.

Second, have a look at options_from_collection_for_select for your form here:

http://apidock.com/rails/ActionView/Helpers/FormOptionsHelper/options_from_collection_for_select

Let me know if this helps you at all.

Upvotes: 0

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