Which block method should be used for preparing data

Question

In a standard template block i.e. extends Mage_Core_Block_Template, which method should be used for preparing required block data?

Is it beforeToHtml? or some other?

Im looking to find the most accepted way to load the block with the required data for it to render correctly. For example if the block needs a collection or some other model of data, should this be loaded in the beforeToHtml method or prepareLayout etc etc.

Can you explain a bit what are you trying to achieve? – Marius Jan 05 '14 at 13:31 — Marius, Jan 05 '14 at 13:31
I have edited the question to explain further – Marty Wallace Jan 05 '14 at 13:33 — Marty Wallace, Jan 05 '14 at 13:33

Marius · Accepted Answer · 2014-01-05T21:16:09.980

This is actually a good question.
In the core there are some blocks that use _beforeToHtml to prepare the data. See for example Mage_Catalog_Block_Product_List, Mage_Catalog_Block_Product_List_Crosssell and a lot of admin blocks.
There are also blocks that use the __construct method to process some data. See Mage_Catalog_Block_Product_View_Options, Mage_Checkout_Block_Cart and again a lot of admin blocks.
Some of them use _toHtml to process data. See Mage_Rss_Block_Catalog_New, Mage_Sales_Block_Order_Email_Items_Order_Grouped.

My vote goes for... neither.
I like using lazy loading. So in my custom blocks I implement methods that process data only when needed. Let's take your example. "The block needs a collection."
I create the method

public function getSomeCollection(){
    if (!$this->hasData('_some_collection')){
        $someCollection = 'Magic happens here';
        $this->setData('_some_collection', $someCollection);
    }
    return $this->getData('_some_collection')
}

This way I'm sure that my collection is loaded only when calling it the first time. The result is cached in the block _data member so it's not processed twice if called twice.
So I call this method in the phtml file when needed.

The _ in the front of _some_collection is there so I'm sure that you cannot call setSomeCollection. If you don't need this restriction you can skip the underscore.

Which block method should be used for preparing data

1 Answers1