Magento 2 Blocks – How to Load All Child Blocks in Controller

So I came up with a solution that works just awesome. I added another controller action and a model to do the Magento Interactions during my ajax calls. So let me show you how it's done, I hope somebody can profit from this sooner or later :)

My new Action:

public function updateAction ()
   {

      //Instantiate Product Model
      $productModel = Mage::getModel('doorconfig/product');

      //Get Updated Values from the Model
      $currentProduct = $productModel->getProduct($_POST);
      $currentProductId = $currentProduct->getId();
      $currentProductUrl = $currentProduct->getProductUrl();
      $currentPrice = $productModel->getPrice($currentProductId);
      $currentType = $this->getRequest()->getPost('doorconfig_type');
      $currentSize = $this->getRequest()->getPost('doorconfig_size');
      $currentProductBaseImgUrl = $productModel->getDoorBaseImgUrl($currentType,$currentSize);

      //Populate Resultarray
      $result = array("currentProductId"=>$currentProductId,"currentPrice"=>$currentPrice,"currentProductUrl"=>$currentProductUrl,"currentProductBaseImgUrl"=>$currentProductBaseImgUrl);

      //Encode Result in JSON
      $this->getResponse()->setBody(Mage::helper('core')->jsonEncode($result));

      return $result;
   }

My model just got most of the business logic from my block, so nothing special to point out about that.

And finally the updated Ajax section which now triggers my new controller action, receives the result as a JSON encode and changes the values in the DOM:

<script type="text/javascript">

   var $price = "";
   var $baseImgUrl = "";
   var $productUrl = "";
   var $productId = "";
   var $f = $j("#attributeform");
    var $formData;
    var $currentStoreUrl = "<?php echo $currentStoreUrl ?>";

   function ajaxUpdate()
   {

      $j.ajax({
         url: "/doorconfig/index/update",
         type: "POST",
         data: $formData,
         dataType: "json",
         success: function(data) 
                {
                  $productId = data.currentProductId;
                  $price = data.currentPrice;
                  $baseImgUrl = data.currentProductBaseImgUrl;
                  $productUrl = data.currentProductUrl;
                     $j("#result").text($price);

                     $j("#addtocart").attr('href',  $currentStoreUrl + "checkout/cart/add?product=" + $productId + "&qty=1");
                     $j("#productimg").attr('src', $baseImgUrl);

                     console.log(data);

                   },
            error: function(error)
                  {
                     console.log("Error:");
                     console.log(error);
                     alert("ERROR");
                  }
        });
    };

   $j(document).ready(function() 
   {

      $j("#result").text('<?php echo $defaultProductPrice; ?>');
      $j("#addtocart").attr('href', '<?php  echo $currentStoreUrl . "checkout/cart/add?product=" . $defaultProductId . "&qty=1" ?>');
      $j("#moreinfo").attr('href', '<?php echo $defaultProductUrl; ?>');
      $j("#productimg").attr('src', '<?php echo $defaultProductImgUrl; ?>');
      $j("#attributeform")[0].reset();

      $j("form[name=attributeform]").change(function () 
      {

         $formData = $f.serialize();
         ajaxUpdate();
      })
   });   

</script>

If you need any further explanation or wanna improve something please comment :)

Regarding #1, the registry does still exist, very similar to what you know from Magento 1. It's just moved. See: \Magento\Framework\Registry

Add it to your constructor via dependency injection, and then you can use your familiar $registry->register($key, $value) and $registry->registry($key) methods to store/access data.

I'd recommend poking around the \Magento\Framework namespace if you haven't already. A lot of what was accessible from Mage or App before is still there, just split out.

As far as best practices, I can't answer that, but I expect the answer would be to keep as much logic out of the controller as possible. Looking at the core is probably your best bet. For instance, see the customer address edit page: Basic controller; extensive block--including pulling the address ID and loading, if necessary. They handle that directly in the block; they don't do it in the controller and then pass it around.