如何在javascript回调中访问更新的对象（而不是旧对象）

Question

Building on the helpful and working solution presented here , I'm trying to fix my update callback as well.

Problem is, the specific unit that I'm trying to extract data from is always the old cached version, even though this callback is triggered by a successful update action.

// callback triggered by the update action

$('.best_in_place').bind("ajax:success", function () {
   ...
    console.log(unit.duration);
    // which is exactly the same as
    console.log(<%= Unit.find(unit.id).unit_users.pluck(:duration).sum %>);
    // and both print the OLD duration val instead of the updated val which is in the database
});

and the unit_users_controller code...

  def update
    @unit = @unituser.unit

    respond_to do |format|
      if @unituser.update(unit_user_params)
        @unit.reload
        logger.info('-----------------------------------------------------------------')
        logger.info('@unit.duration in the controller is ' + @unit.duration.to_s) # which is the correct value
        logger.info('-----------------------------------------------------------------')
        gon.unit_duration = @unit.duration # an experiment which didn't work for me
        format.json {respond_with_bip(@unituser) }
      else
        # format.html { render :action => 'edit' }
        format.json { respond_with_bip(@unituser) }
      end
    end
  end

I've tried several versions of unit.reload , and nothing helps. Maybe I was putting it in the wrong place?

Answer 1

This isn't about caching. Your Ruby code is evaluated server -side, before the JavaScript is ever send to the client, and it's only evaluated once, long before the AJAX request can happen.

The client never sees this line:

console.log(<%= Unit.find(unit.id).unit_users.pluck(:duration).sum %>);

All the client will see is something like:

console.log(32); // or whatever the sum is

You cannot use <%= %> here. That will always give you the original value. Instead, you need to send the new value to the client in response to the AJAX request.

Answer 2

I did this one sometime ago here is my code, maybe it will help you:

Javascript:

$(document).ready(function() {
  $('.price_bind').bind("ajax:success", function (event, data, status, xhr) {
      var parsed_data = jQuery.parseJSON(data);
      $(this).text(parsed_data.newprice);
      $(this).parentsUntil('body').find(".totalpricep span").text(parsed_data.totalprice);
  });
}

View:

<%= best_in_place detail, :price, :classes => 'price_bind', :path => purchase_detail_path(@purchase, detail)%>

Controller:

 def update
    respond_to do |format|
      if @detail.update_attributes(params[:detail])
        @n=@detail.mk_bal
        @r=false
        if @detail.purchase != nil
          @p=@detail.purchase.totalprice
        if params[:detail]['status'] && @purchase.step==1
          @remdet = @purchase.details.where(:step => 1, :status => false)
          if @remdet.empty?
            @purchase.update_attribute(:step, 2)
            @r=true
          end  
        end
        else
          @p=nil
        end
        format.html { redirect_to @detail, notice: 'Detail was successfully updated.' }
        format.json { render :json => {:newprice => @n, :totalprice => @p, :newstatus => @detail.status, :refresh => @r}}
      else
        format.html { render action: "edit" }
        format.json { render json: @detail.errors, status: :unprocessable_entity }
      end
    end
  end