Delete nested object

Question

Hi im struggling with adding a link to delete an object thats nested. I have list application that has many tasks nested like this.

resources :lists do
  resource :tasks
end

I have read this post but it does not work for me. I want a link to delete in this code below

    <h4>Tasks</h4>
<% @list.tasks.each do |task| %>
    <%= task.desc %>
    <%= link_to "Delete", list_task_path(list, task), :method => :delete %><br />
<% end %>

But it gives me the following error

undefined local variable or method `list' for #<#<Class:0x007f9adc555db0>:0x007f9adc547828>

EDIT: Now i get the following error when i refreshed the page

No route matches {:action=>"show", :controller=>"tasks", :list_id=>#<List id: 28, name: "Julklappar", user_id: 1, created_at: "2012-12-22 17:40:05", updated_at: "2012-12-22 17:40:05">, :id=>#<Task id: nil, desc: nil, completed: false, list_id: 28, created_at: nil, updated_at: nil>}

Rake routes:

pierre@ubuntu:~/todolist$ rake routes
              list_tasks GET    /lists/:list_id/tasks(.:format)          tasks#index
                         POST   /lists/:list_id/tasks(.:format)          tasks#create
           new_list_task GET    /lists/:list_id/tasks/new(.:format)      tasks#new
          edit_list_task GET    /lists/:list_id/tasks/:id/edit(.:format) tasks#edit
               list_task GET    /lists/:list_id/tasks/:id(.:format)      tasks#show
                         PUT    /lists/:list_id/tasks/:id(.:format)      tasks#update
                         DELETE /lists/:list_id/tasks/:id(.:format)      tasks#destroy
                   lists GET    /lists(.:format)                         lists#index
                         POST   /lists(.:format)                         lists#create
                new_list GET    /lists/new(.:format)                     lists#new
               edit_list GET    /lists/:id/edit(.:format)                lists#edit
                    list GET    /lists/:id(.:format)                     lists#show
                         PUT    /lists/:id(.:format)                     lists#update
                         DELETE /lists/:id(.:format)                     lists#destroy
        new_user_session GET    /users/sign_in(.:format)                 devise/sessions#new
            user_session POST   /users/sign_in(.:format)                 devise/sessions#create
    destroy_user_session DELETE /users/sign_out(.:format)                devise/sessions#destroy
           user_password POST   /users/password(.:format)                devise/passwords#create
       new_user_password GET    /users/password/new(.:format)            devise/passwords#new
      edit_user_password GET    /users/password/edit(.:format)           devise/passwords#edit
                         PUT    /users/password(.:format)                devise/passwords#update
cancel_user_registration GET    /users/cancel(.:format)                  devise/registrations#cancel
       user_registration POST   /users(.:format)                         devise/registrations#create
   new_user_registration GET    /users/register(.:format)                devise/registrations#new
  edit_user_registration GET    /users/edit(.:format)                    devise/registrations#edit
                         PUT    /users(.:format)                         devise/registrations#update
                         DELETE /users(.:format)                         devise/registrations#destroy
                    root        /                                        lists#index

Edit #2 This is my lists/show.html.erb file

<p id="notice"><%= notice %></p>

<h2><%= @list.name %></h2>

    <h4>Tasks</h4>
    <% @list.tasks.each do |task| %>
        <%= task.desc %>
        <%= link_to "Delete", list_task_path(@list, task), :method => :delete %>
    <% end %>

<%= form_for [@list, @task] do |form| %>

    <p><%= form.text_field :desc %> <%= form.submit %></p>

<% end %>

<%= link_to 'Edit', edit_list_path(@list) %> |
<%= link_to 'Back', lists_path %>

lists controller

  def show
    @list = current_user.lists.find(params[:id])
    @task = @list.tasks.new
  end

Dennis Hackethal · Accepted Answer · 2013-01-13 20:52:57Z

1

Your link should be:

<%= link_to "Delete", list_task_path(@list, task), :method => :delete %>

When looping through @list.tasks, you are only localizing task through |task| - but @list always stays @list.

The other problem is in your controller: @task = @list.tasks.new - your building a new task here, which is needed for your form. However, this task is new, which means it hasn't been saved yet - you simply cannot build a link to delete it, because it doesn't exist in the database yet. You can avoid this by building the task directly in the form, not in the controller.

Get rid of this line in the controller:

@task = @list.tasks.new

And change your form to:

<%= form_for [@list, @list.tasks.build] do |form| %>

edited Jan 13, 2013 at 20:52

answered Jan 13, 2013 at 20:16

Dennis Hackethal

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4 Comments

Pierre Over a year ago

Now i get the following error "undefined method `list_task_path' for" Rake routes: No route matches {:action=>"show", :controller=>"tasks", :list_id=>#<List id: 28, name: "Julklappar", user_id: 1, created_at: "2012-12-22 17:40:05", updated_at: "2012-12-22 17:40:05">, :id=>#<Task id: nil, desc: nil, completed: false, list_id: 28, created_at: nil, updated_at: nil>}

Dennis Hackethal Over a year ago

Please run rake routes and add the output to your question.

Dennis Hackethal Over a year ago

It looks like the task id is nil, that's why it is trying to generate a link like DELETE /lists/1/tasks/nil-id. In plain english, you cannot delete a task that hasn't been saved yet - if it had been saved, it would have an id. Are you doing @list.tasks.build or @list.tasks.new somewhere in the controller or view before rendering the loop above?

Dennis Hackethal Over a year ago

Can you please also show us the show method in your lists controller?

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