Magento-module renamed, but Magento keeps asking for the old helper class

Magento, versions CE 1.4.2, 1.5.0.1, 1.5.1.0

I have had to adapt a payment module for Magento, following all recipes, config.xml, system.xml, etc/module/Mycompany_Mypaymentmodule.xml, which all work fine.

But recently, I've double checked and found an error: in my config.xml, I had put:

<config>
<modules>
    <Mage_Mycompany>
        <version>0.1.0</version>
    </Mage_Mycompany>
</modules>

...

That's because originally, the module was supposed to be placed inside the community-folder.

Following the guidelines, I've rewritten classes, xml's et cetera to reflect the local codepool. That too went well (except for an error that I had debugged).

However, inside the config.xml, I have renamed the modules-tag, like so:

<config>
    <modules>
        <Mycompany_Mypaymentmodule>
        <version>0.1.0</version>
        </Mycompany_Mypaymentmodule>
</modules>

The strange thing is that Magento now keeps asking me for the old Helper-class-file when I go to the Payment Methods in the backend, resulting in:

Fatal error: Class 'Mage_Mycompany_Helper_Data' not found in path\to\app\Mage.php on line 520

In other words, Magento keeps asking for a helper class of my old, pre-renamed module, which of course is nowhere to be found.

I've done an extensive search in all files, but nowhere is the string Mage_Mycompany to be found, so my guess is Magento is trying to load this helper class out of a database table. Of course, I've cleared the cache and rebuilt all indexes multiple times, and removed all cache files. I also checked practically all database tables, but to no avail.

Second, when I create the helper class by hand in app/code/community/Mage/Mycompany/Helper/Data.php, all goes well, which to me sounds strange, because the class itself should not be called (since it is never mentioned in any co开发者_StackOverflow中文版nfig.xml).

I must be missing something, and perhaps the class name is generated on the fly, but I really do not know how to avoid it or to fix it... so any help is appreciated!

---

Step one, of course, is to clear your cache.

If clearing cache doesn't work.

Step 2: The data helper class is used to translate strings for a module. That is, each data helper has a method

$helper->__('Translate this symbol');

that will translate a string per that module's helper file.

Throughout the system, there are several XML files where you may want certain nodes to be translated. The syntax looks something like this.

<dhl translate="label" module="usa">
    <label>The Label</label>
</dhl>

Here you're telling magento to translate the "label" node enclosed in dhl, and to use the usa module to do it. That is, use the helper instantiated like

$Mage::getModel('usa/data');
//same thing as above, helpers default to data
Mage::getModel('usa');

to translate the label

$helper->__('The Label');

My guess is one of your XML files still has your old module configure for translation

<sometag module="mycompany" translate="someothertag" />

which makes magento look for a helper that's no longer there, and boom, there's your error.

---

Tha Data helper is loaded when you call the translation helper, ie: Mage::helper('modulename')->__("some string to translate").
In your config .xml, have you declared the module's helper class?:

<config>
    ...
    <global>
        ...
        <helpers>
            <yourmodule>
                <class>Yourcompanyname_Yourmodule_Helper</class>
            </yourmodule>
        </helpers>
        ...
    </global>
    ...
</config>