在Rails 4中提交AJAX请求时遇到问题

Question

I've been following http://blog.markhorgan.com/?p=522 as a guide to update an image in a form with an ajax callback. Image saves fine but I want to do some clever ajax so the page doesn't refresh.

Here's my code:

edit.html.haml:

  #promo-image
     = render partial: 'promo_image' 

_promo_image.html.haml:

= form_for( @property, remote: true) do |f|
  = f.file_field :promo_image, :pattern => "^.+?\.(jpg|JPG|jpeg|JPEG|png|PNG|gif|GIF)$", :id => 'promo-image-upload'
  = f.submit 'Update'
= image_tag @property.promo_image.url(:medium)

properties_controller.rb

def update
 @property = Property.find(params[:id])

 if @property.update(property_params)
   format.js
 else
   render 'edit'
 end
end

update.js.haml:

$("#promo-image").html("#{escape_javascript(render partial: 'promo_image',)}");

With the code outlined above I get error pointing to the format.js line:

ArgumentError in PropertiesController#update too few arguments

Can anyone see where I'm going wrong or perhaps point me in the right direction?

Many thanks! Steve

UPDATE

Just to be clear, I want to be able to update JUST the Div stated here:

update.js.haml:

$("#promo-image").html("#{escape_javascript(render partial: 'promo_image',)}");

This code works, but refreshes the whole page:

 respond_to do |format| format.html { redirect_to edit_property_path(@property) } format.js end 

FURTHER UPDATE

Just to be clear on my motives, I want to be able to update an element on the edit page, and not be redirected to a different one, eg show or index. This is for UI reasons. The guide above talks about the exact same thing.

FINAL UPDATE

The issue is because I'm using a file upload, this can't be achieved via ajax. For those in a similar situation see here: Rails form_for with file_field and remote => true and format => :js

A solution could lay here, and I will investigate this: https://github.com/JangoSteve/remotipart

Thanks to everyone for helping me work out the error of my ways!

Answer 1

Regarding your first update, you said that this code works, but refreshes the page:

respond_to do |format|
  format.html { redirect_to edit_property_path(@property) } 
  format.js
end

If that is the case, that means the incoming request is an html request, rather than an AJAX request. So the format.html block runs and redirects the browser to the same page, which now has the updated image.

What you need to do is figure out why the page is not sending the request as AJAX. You can see the request format if you look at the terminal output (if running locally). It will say something like:

Processing by ControllerName#action as [format]

Format needs to be JS in order for the format.js to render update.js.haml.

UPDATE:

Now that you mention it, the issue is indeed the file_upload field. Uploading files with AJAX is actually not possible with the Forms Helper. See the docs :

Unlike other forms making an asynchronous file upload form is not as simple as providing form_for with remote: true. With an Ajax form the serialization is done by JavaScript running inside the browser and since JavaScript cannot read files from your hard drive the file cannot be uploaded. The most common workaround is to use an invisible iframe that serves as the target for the form submission.

I did a quick search on Google and found the remotipart gem , which seems to specialize in doing this. I don't have any experience with it though, so you're on your own from here on. :)

Answer 2

Try changing your update action to

def update
  @property = Property.find(params[:id])

 if @property.update(property_params)

    respond_to do |format|
      format.html { redirect_to properties_path } 
      format.js
    end
  else
    render 'edit'
  end
end

Source