jquery doesn't call success method on $.ajax for rails standard REST DELETE answer

Question

May be such problem is not new, but I didn't find anything similar. I have such jQuery code:

$.ajax({ 
  url : ('/people/'+id), 
  type : 'DELETE', 
  dataType : 'json', 
  success : function(e) {
    table.getItems(currentPage);
  }
});

My Rails controller looks like this:

def destroy
    @person = Person.find(params[:id])
    @person.destroy

    respond_to do |format|
      format.html { redirect_to(people_url) }
      format.json  { render :json => @person, :status => :ok }
    end
end

This is working.

But when I use the following (as generated by standard), the success callback doesn't get called:

def destroy
    @person = Person.find(params[:id])
    @person.destroy

    respond_to do |format|
      format.html { redirect_to(people_url) }
      format.json  { head :ok }
    end
end

Tested under rails 3.0.3, jQuery 1.4.2 and Firefox 3.6.13.
Firebug says, that query is fired and returns 200 OK in both cases, item is deleted in both cases too. But in second case the callback is not called.

Is there a significant difference in REST, and is there a way to utilize jQuery by using the scaffolded controller?

Answer 1

I have run across this a few times and the answer is deceptively simple.

You are using dataType : 'json' in your $.ajax call, so jQuery is expecting a JSON response. With head :ok Rails returns a response containing a single space (http://github.com/rails/rails/issues/1742), which is not accepted by jQuery as valid JSON.

So if you really expect to get either an error or a bare 200 OK header, just set dataType : 'html' in your request and it should work (if you don't set dataType, jQuery will try to guess at what the type is based on response headers, etc., and could still guess json, in which case you'd still have this problem). If you actually expect to get JSON back, instead of using head :ok render something valid with JSON (see comments) or just use head :no_content as suggested by @Waseem