Create a new Block in Magento

Question

I asked this question yesterday Static block on home page in Magento, which answered my question about hooking a cms/block to an existing block (content, in that example).

But now I would like to know how to create my own block.

I have this in my .phtml template:

<?php echo $this->getChildHtml('home_flash') ?>

And this in my cms.xml file

<reference name="home_flash">
  <block type="cms/block" name="home-page-flash" before="content">
    <action method="setBlockId"><block_id>home-page-flash</block_id></action>
  </block>
</reference>

But this is not working.

I have also tried to create my own block type, (by copying the breadcrumbs declaration) in the page.xml file:

<block type="page/html_home_block" name="home_block" as="home_block" template="page/template/home_block.phtml"/>

That file exists but isn't being rendered.

However when I reference the block like this:

<block type="page/html_breadcrumbs" name="home_block" as="home_block" template="page/template/home_block.phtml"/>

It renders my home block template, but the original cms/block is not attached to it.

Hope all the different cases show what is happening and highlight the gap in my knowledge well enough for someone to answer, do I have to "register" my new "home_block" type somewhere?

Answer 1

There are many different blocks available that you can use without creating your own. In this case I think core/text_list would be suitable because it doesn't require a template and can have as many child blocks within it as you need.

<?xml version="1.0"?>
<layout version="0.1.0"><!-- All layout files start with this -->
    <cms_index_index><!-- Index directive is the same as "home" page -->
        <reference name="root"><!-- For more blocks that can be referenced see "default" directive -->
            <block type="core/text_list" name="home_flash">
                <block type="cms/block" name="home-page-flash">
                    <action method="setBlockId"><block_id>home-page-flash</block_id></action>
                </block>
            </block>
        </reference>
    </cms_index_index>

    <!-- More directives might go here -->

</layout>

Other useful block types worth knowing are core/text and core/template which correspond to Mage_Core_Block_Text and Mage_Core_Block_Template respectively. They get used the most.
Your home made block type of page/html_home_block didn't have any PHP class with a matching name, and if you were genuinely creating your own you wouldn't be able to use the page prefix since Magento already does.

To create a block you only need a <block> tag in the layout file.
To create a block type you need to write a PHP class, give it a namespace and declare it as part of a module.
To add to an existing block is the time when you use a <reference> tag.

There are many fine articles at Magento Knowledge Base including some on Theming & Design.