如何从事件ajax的响应中获取数据：Rails 5.1中的错误

Question

Iam building a form in Rails. I want to submit it by ajax, so I setted remote: true

<%= form_for @post, html: { multipart: true }, remote: true  do |f| %>
    ...
<%= end %>

In my controller:

def create
    @post = Post.new(post_param)

    respond_to do |format|
       if @post.save
          format.html { redirect_to @post, notice: 'Post was successfully created.' }
          format.json { render :show, status: :created, location: @post }
       else
          format.html { render json: @post.errors, status: 400 }
          format.json { render json: @post.errors, status: 400 }
      end
    end
end

In form on view

$('#new_post').on('ajax:success', function(data) {
    console.log(data);
}).on('ajax:error', function(evt, xhr, status, error) {
    console.log(xhr);
});

But in event 'ajax:error', I can't parse to get data about validation errors of post. All params 'xhr', 'status', 'error' both equal undefined.

How to parse response in 'ajax:error' to get data about validation errors ?

Answer 1

Rails 5.1 introduced rails-ujs , which changes the parameters of these event handlers. The following should work:

// ...
.on('ajax:error', function(event) {
    var detail = event.detail;
    var data = detail[0], status = detail[1],  xhr = detail[2];
    // ...
});

Source: http://edgeguides.rubyonrails.org/working_with_javascript_in_rails.html#rails-ujs-event-handlers