RoR 和 Ajax：如何使我的 Ajax 请求工作？

Question

I'm tying to do an Ajax request on a delete method for active storage files so my page won't reload.

I have two controllers: 'project_steps' (i'm using wicked gem) and 'projects'.

My view: project_steps/fourth_step.html.erb

<% if @project.supporting_docs.attached? %>
  <div id="remove_file">
    <%= render partial: "existing_files", :locals => {project: @project} %>
  </div>
<% end %>

My partial: project_steps/_existing_files.html.erb

<% @project.supporting_docs.each do |file| %>
  blah blah
  <%= link_to 'Remove', delete_file_attachment_project_url(file.signed_id),
     method: :delete, remote: true, class: "btn btn-sm btn-danger" %>
<% end %>

My projects_controller:

def delete_file_attachment
     file = ActiveStorage::Blob.find_signed(params[:id])
     file.attachments.first.purge
     respond_to do |format|
       format.js
     end
   end

projects/delete_file_attachment.js.erb:

$('#remove_file').html("<%= j render(partial: 'project_steps/existing_files', :locals => 
     {project: @project}) %>")

My Routes:

resources :projects do
  member do
    delete :delete_file_attachment
  end
end

scope 'projects/:project_id' do
  resources :project_steps
end

My Error

ActionView::Template::Error (undefined method `supporting_docs' for nil:NilClass):
    3:     <strong>You have attached the following files:</strong>
    4:   </div>
    5:   <br>
    6:   <% @project.supporting_docs.each do |file| %>
    7:     <div class="row">
    8:       <div class="col">

My delete works fine and I see why the error is there but i'm wondering how can I make Ajax work and what i'm doing wrong? Happy to provide as much code as needed. Ty.

PS if anyone would like to suggest a solution other than going through partial you feel might be better by all means!

Answer 1

When using partials with locals, you access the variable without the @ , ie to access the variable in project_steps/_existing_files.html.erb you need to use project instead of @project :

project_steps/_existing_files.html.erb

<% project.supporting_docs.each do |file| %>
  blah blah
  <%= link_to 'Remove', delete_file_attachment_project_url(file.signed_id),
     method: :delete, remote: true, class: "btn btn-sm btn-danger" %>
<% end %>

Please also note that using @project in your projects/delete_file_attachment.js.erb doesn't work if you don't set the @project variable in the controller action delete_file_attachment , ie you'd probably need to add a line along @project = Project.find... to your delete_file_attachment method.

See the Layouts and Rendering in Rails guide for more informations about using locals in partials.