Validation for form_remote_tag

[b0rdslide]

Hi,

I've just been playing around with some of the builtin ajax capabilities of rails but I've run into a bit of a roadblock.

So far I've got a drag-n-drop sortable list working with a remote form that adds new items and reloads the list so that the new item is sortable. This all works fine up until a user enters something in the remote form that hits a validation rule!

Has anyone worked out a simple way of handling validation errors for ajax requests?

The only solution I've found so far is here: http://www.bigsmoke.us/ajax-validation-on-rails/ but that looks over complicated and not very rubyish

Kev

[Luke Redpath]

I use a simple controller action to handle inline AJAX edits - as well as sending the updated value to the server, I also send the model name and the attribute thats being updated and the ID of the record. You can then load the record using the class name and the ID, update the specified attribute with the given value, then check if that single value is valid. If it is, then you can call save(false) which will bypass validations for the entire object (as you only care about the attribute being edited). I can't remember the code I use off of the top of my head but its something like this:

def process_ajax_edit
  @obj = eval(params[:klass].camelize).find(params[:id])
  @obj.send("#{params[:attr]}=", params[:value])
  @obj.valid?
  if @obj.errors.invalid?(params[:attr])
    render :text => @obj.errors.on(params[:attr]).to_s, :status => 500
  else
    @obj.save(false)
    render :text => @obj.send(params[:attr]).to_s
  end
end

You can handle the error message in the AJAX onFailure callback (which is why we send a 500 status with the error message) - I find a simple Javascript alert with the error suffices, its much less hassle than putting it in your UI somewhere.

[alistair_b]

www.ajaxscaffold.com has an interesting solution.

they have a <div id="messages">...</div> that is usually hidden. this allows you from the server to do stuff like this.

def open_version_detail
    begin
      @brief = Brief.find_version params[:id], params[:version]
      @successful = true
    rescue
	  flash[:error], @successful = $!.to_s, false
    end
end

and in the open_version_detail.rjs

@options = { :scaffold_id => params[:scaffold_id], :action => "version_detail", :id => params[:id], :version => params[:version] }
@view_options = @options.merge(:action => "view")

if @successful
	page.hide element_row_id(@view_options)
	page.insert_html :bottom, scaffold_tbody_id(@options), :partial => 'view_detail', :locals => { :hidden => true }
	
	page << "new TableRow.MoveAfter('#{element_row_id(@view_options)}', '#{element_row_id(@options)}');"  
    page.show element_row_id(@options)
else
	page.replace_html scaffold_messages_id(@options), :partial => 'messages'
end

page.hide loading_indicator_id(@view_options)

the messages partial will handles the rest. red for error, purple and blue for the other 2