OpenmageLabs ProductTaxClasses

Magento 1 / OpenMage module that allows administrators to restrict which product Tax Classes are available when creating or editing a product in the admin panel.

🧩 Features

• Hide specific product tax classes in the admin product form.
• Keep the selected tax class visible even if it is hidden in configuration.
• Fully configurable via System > Configuration > Sales > Tax > Product Tax Classes.
• Compatible with both Magento 1.9.2.4+ and OpenMage 20.10.0+ (with layout handling differences noted below).

⚙️ Installation

1. Copy all module files into your Magento/OpenMage root directory.
2. Clear the Magento cache (System > Cache Management).
3. Logout and log back into the admin panel to trigger setup script execution.

🛠️ Configuration

Go to:

System > Configuration > Sales > Tax > Product Tax Classes

• Visible Product Tax Classes – Select which tax classes will appear in the product edit interface.
• Note: By default, all product tax classes are available.

💡 How It Works

• The module uses an observer (adminhtml_block_html_before) to filter the <select> options in the admin form.
• A JavaScript enhancement hides unselected options without removing them entirely from the DOM.
• The selected tax class (if hidden) remains visible and selectable.
• The list of visible tax class IDs is injected into the admin page as a global JS variable (window.visibleTaxClassIds).

🧪 Compatibility

Magento Version	Status	Notes
OpenMage 20.10.0+	✅	Fully compatible with layout XML format used in this module.
Magento 1.9.2.4	✅	JS injection requires slight layout XML adjustment (see below).

Layout XML for Magento 1.9.2.4

If the default layout does not inject inject.phtml properly, use this workaround:

<adminhtml_catalog_product_edit>
    <reference name="content">
        <block type="core/template" name="openmagelabs.producttaxclasses.jsinject" template="openmagelabs/producttaxclasses/inject.phtml" />
    </reference>
</adminhtml_catalog_product_edit>

📝 License

MIT License