How to use XML with condition in Magento 1?

Question

This is my XML from layout:

<customer_account_index>
    <reference name="content">
        <block type="name_module/customer_account_welcome" name="customer_account_dashboard" before="-" template="name_module/customer/account/welcome.phtml"/>
    </reference>
</customer_account_index>
<customer_account_index>
    <update handle="customer_account_dashboard" />
    <reference name="content">
        <block type="cms/block" name="customer_account_dashboard_welcome" before="-">
            <action method="setBlockId"><block_id>succes-startkit</block_id></action>
        </block>
    </reference>
</customer_account_index>

This is the content of my template:

<?php if ($this->shouldDisplayWelcome()):?>
    <div class="welcome-msg">
        <?php echo $this->getChildHtml('customer_account_dashboard_welcome') ?>
    </div>
<?php endif;?>

and my function from my block:

public function shouldDisplayWelcome()
{
        $session = Mage::getSingleton('core/session');
        $welcome = $session->getShowWelcomeMessage();

        if ($welcome === true) { 
            $session->setShowWelcomeMessage(false);

            return true;
        }

        return false;
}

Depends on what my function returns I want to display my static block or not. What am I doing wrong from the layout?

Thanks

[UPDATE]

Right now this version of the XML doesn't work:

 <customer_account_index>
        <reference name="content">
            <block type="cms/block" name="customer_account_dashboard_welcome" before="-">
                <action method="setBlockId" helper="mynamespace_mymodule/customer/shouldDisplayWelcome">
                    <block_id>succes-startkit</block_id>
                </action>
            </block>
        </reference>
    </customer_account_index>

If i make a syntax error in my helper, I got the error message, but no matter what i return true or false in my function my static block is still displayed.

Answer 1

You can try this ... then your helper should return block id

<reference name="content">
    <block type="cms/block" name="customer_account_dashboard_welcome" before="-">
        <action method="setBlockId">
            <block_id helper="YOURMODULE/YOURHELPER/shouldDisplayWelcome"/>
        </action>
   </block>
</reference>

Answer 2

You can add the helper parameter, like that sample below, so add the return of your helper like what you want to return:

<reference name="content">
    <block type="cms/block" name="customer_account_dashboard_welcome" before="-">
        <action method="setBlockId">
            <block_id helper="YOURMODULE/YOURHELPER/shouldDisplayWelcome"/>
        </action>
   </block>
</reference>

Helper called Data.php

public function() {

        $session = Mage::getSingleton('core/session');
        $welcome = $session->getShowWelcomeMessage();

        if ($welcome === true) { 
            $session->setShowWelcomeMessage(false);

            return 'block_id';
        }

        return false;

}

References:

Conditionally show/hide blocks in layout XML

https://stackoverflow.com/questions/5596193/magento-xml-layouts-specify-value-for-ifconfig