When extending Mage_Tax_Helper_Data admin menu Sales>Taxes disappears

Question

I'm trying to extend properly the core class Mage_Tax_Helper_Data with a module named "smartvat". All seem ok, my config.xml file:

<?xml version="1.0"?>
<config>
  <modules>
    <Bsinformatica_Smartvat>
      <version>0.1.1</version>
    </Bsinformatica_Smartvat>
  </modules>
  <global>
    <helpers>
      <smartvat>
        <class>Bsinformatica_Smartvat_Helper</class>
      </smartvat>
    </helpers>
      <helpers>
        <tax>
          <rewrite>
            <data>Bsinformatica_Smartvat_Tax_Helper_Data</data>
          </rewrite>
        </tax>
      </helpers>
    <models>
      <tax>
        <rewrite>
          <config>Bsinformatica_Smartvat_Tax_Model_Config</config>
        </rewrite>
      </tax>
    </models>
      </global>
</config>

and my class...

class Bsinformatica_Smartvat_Tax_Model_Config extends Mage_Tax_Model_Config {

    public function getPriceDisplayType($store = null)
    {
        // code goes here
    }

}

All it seems ok and the class id properly rewrited. But doing this the admin menu Sales>Taxes disappear. If I comment out:

<helpers>
    <tax>
        <rewrite>
            <data>Bsinformatica_Smartvat_Tax_Helper_Data</data>
        </rewrite>
    </tax>
</helpers>

this section the menu displays correctly. Can someone help me?

Answer 1

Your directory structure and config are not matching.

Please update your files and directory structure as follows.

1) app\etc\modules\Bsinformatica_Smartvat.xml

<?xml version="1.0" encoding="UTF-8" ?>
        <config>
    <modules>
        <Bsinformatica_Smartvat>
            <active>1</active>
            <codePool>local</codePool>
        </Bsinformatica_Smartvat>
    </modules>
</config>

2) app\code\local\Bsinformatica\Smartvat\etc\config.xml

<?xml version="1.0" encoding="UTF-8" ?>
<config>
    <modules>
        <Bsinformatica_Smartvat>
            <version>0.1.1</version>
        </Bsinformatica_Smartvat>
    </modules>
    <global>
        <helpers>
            <smartvat>
                <class>Bsinformatica_Smartvat_Helper</class>
            </smartvat>

            <tax>
                <rewrite>
                    <data>Bsinformatica_Smartvat_Helper_Tax_Data</data>
                </rewrite>
            </tax>
        </helpers>
        <models>
            <smartvat>
                <class>Bsinformatica_Smartvat_Model</class>
            </smartvat>
            <tax>
                <rewrite>
                    <config>Bsinformatica_Smartvat_Model_Tax_Config</config>
                </rewrite>
            </tax>
        </models>
    </global>
</config>

3) app\code\local\Bsinformatica\Smartvat\Helper\Tax\Data.php

<?php

class Bsinformatica_Smartvat_Helper_Tax_Data extends Mage_Tax_Helper_Data
{

}

4) app\code\local\Bsinformatica\Smartvat\Model\Tax\Config.php

<?php

class Bsinformatica_Smartvat_Model_Tax_Config extends Mage_Tax_Model_Config
{

}

This will rewrite both helper and model.

Hope this helps you.