XML tag to add array in cache tag for layout file

Question

As magento1.9.2 is added cachetags function in to construct functon i must have to give seperate cachetags for each block element because its get conflict with varnish to read key. i have solved this issue in.phtml file to set key like below

 $this->getLayout()->createBlock('cms/block','',
         array(
         'cache_lifetime' => false,
         'cache_tags' => array(Mage_Cms_Model_Block::CACHE_TAG."_twocmspages")
                          ))->setBlockId("twocmspages")->toHtml(); 

but if need to assign same cache_tags using xml with setMethod how can i do this.

<block type="cms/block" name="block_id">
... set cachetag here
</block>

Is any one has idea how to add cache_tag array arrgument from XML ?

your help will be appreciated here.

Answer 1

Arguments in <action> can be defined as nested elements and will be converted to array:

<block type="cms/block" name="block_id">
    <action method="setTags">
        <tags>
            <tag1>cms_block_twocmspages</tag1>
            <tag2>( just in case you want to add more tags )</tag2>
        </tags>
    </action>
</block>

It should be noted that <tag1> and <tag2> will be the array keys, so you cannot use the same tag name and you cannot pass arrays with numeric indexes because XML tags cannot be numbers.

A more flexible solution is using JSON. Just specify which argument should be parsed as JSON with the json attribute of <action>:

<block type="cms/block" name="block_id">
    <action method="setTags" json="tags">
        <tags>["cms_block_twocmspages"]</tags>
    </action>
</block>

Answer 2

Not sure if you can do it directly from the layout but you can do a trick.
Everything parameter you pass to an <action> tag can come from a helper.

Something like this:

<block type="something/here" name="some_name">
    <action method="setSomething">
        <something helper="module/getSomething" />
    </action>
</block>

This means that the method setSomething from the block something/here will be called and will receive as parameter the result of Mage::helper('module')->getSomething().

So you can try the same for your code:

<block type="cms/block" name="block_id">
    <action method="setCacheTags">
         <tags helper="modulename/getBlockTags" />
    </action>
</block>

now just implement the method getBlockTags() in the helper Namespace_Modulename_Helper_Data that returns the array with your tags.

If you don't to add the method in a helper called Data, let's say you add it in the helper Namespace_Modulename_Helper_Something you need the tags tag like this:

<tags helper="modulename/something/getBlockTags" />