In the xml file for a module, I call a custom field class:

    <fields name="params">
        <fieldset name="basic" addfieldprefix="Myextension\Name\Administrator\Field">
            <field name="category_id" type="categorylist" default="0"
                   label="MOD_MYMODULE_PARAM_CATEGORYLIST_NONE" multiple="true" size="5">
                <option value="0">MOD_MYMODULE_PARAM_CATEGORYLIST_NONE</option>

In the file CategorylistField, I call HTMLHelper:

class CategorylistField extends ListField
    protected $type = 'CategoryList';

    protected function getInput(): string
        return HTMLHelper::_('myextensionhtml.categorylist', $options, $this->element, $attribs, $this->value);

When I edit the module, I have an error:

500 JHtml myextensionhtml not found on JROOT\libraries\src\HTML\HTMLHelper.php:156

In my component, the call of HTMLHelper::_('myextensionhtml.categorylist' works, why doesn't it work in the module?

1 Answer 1


You need to register the HTML services with the service registry. If your component uses the same convention as Joomla core, then the services are registered during the boot up process of the component. In that case, you can boot the component manually before using HTML services:

// Boot the component.

 return HTMLHelper::_('myextensionhtml.categorylist', $options, $this->element, $attribs, $this->value);

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