CODEWITHSUNDEEP
ruby-on-railsnested-attributes
Dodinas
Dodinas

Reputation: 6805

Rails - Destroy children for nested attributes

I'm banging my head trying to figure this one out. I have the following form, which works great!

  <%= bootstrap_form_for @template do |f| %>
     <%= f.text_field :prompt, :class => :span6, :placeholder => "Which one is running?", :autocomplete => :off %>
     <%= f.select 'group_id', options_from_collection_for_select(@groups, 'id', 'name') %>
     <% 4.times do |num| %>
        <%= f.fields_for :template_assignments do |builder| %>
            <%= builder.hidden_field :choice_id %>
            <%= builder.check_box :correct %>
        <% end %>
      <% end %>
   <% end %>

Then I have my model:

  class Template < ActiveRecord::Base
   belongs_to :group
   has_many :template_assignments
   has_many :choices, :through => :template_assignments
   accepts_nested_attributes_for :template_assignments, :reject_if => lambda { |a| a[:choice_id].blank? }, allow_destroy: true
  end

When the form is submitted, the nested attributes are added beautifully. However, when I want to delete a Template, I also want it to delete all the children "template_assignments" as well, which is what I assumed "allow_destroy => true"

So, I am trying this from the Rails Console (which could be my issue??) I'll do something like:

 >> t = Template.find(1)
 #Which then finds the correct template, and I can even type: 
 >> t.template_assignments
 #Which then displays the nested attributes no problem, but then I try: 
 >> t.destroy
 #And it only destroys the main parent, and none of those nested columns in the TemplateAssignment Model.

Any ideas what I am doing wrong here? Is it because you can't do it in the Rails Console? Do I need to do it in a form instead? If so, how do I achieve this in a form?

Any help would be great!

Upvotes: 2

Views: 5821

Answers (1)

zeantsoi
zeantsoi

Reputation: 26193

Specify that child template_assignments should be destroyed upon the destruction of the parent Template:

# app/models/template.rb
has_many :template_assignments, dependent: :destroy

The following depicts the steps that Rails takes to destroy an object's dependent associations:

# from the Rails console
>>  t = Template.find(1)
#=> #<Template id:1>
>>  t.template_assignments.first
#=> #<TemplateAssignment id:1>
>>  t.destroy
#=> SELECT "template_assignments".* FROM "template_assignments" WHERE "template_assignments"."template_id" = 1
#=> DELETE FROM "template_assignments" WHERE "template_assignments"."id" = ?  [["id", 1]]
>>  TemplateAssignment.find(1)
#=> ActiveRecord::RecordNotFound: Couldn't find TemplateAssignment with id=1

The :dependent option can be specified on either side of the association, so it can alternatively be declared on the child association, rather than the parent:

# app/models/template_assignment.rb
belongs_to :template, dependent: :destroy

From the Rails docs:

has_many, has_one and belongs_to associations support the :dependent option. This allows you to specify that associated records should be deleted when the owner is deleted

Upvotes: 6

Related Questions