I'm working with latest Joomla 4 beta, and wondering how can I use namespaces with templates so I can start using and developing custom fields for my templates.

I need to know what should I set in the templateDetails.xml file so I can use proper addfieldprefix address for my custom fields.

Some context:

  • what I have and currently use is based on my previous questions asked here: plugin defined custom field - partially works with addfieldpath for templates, use plugin defined custom field inside another plugin, setting extension namespace
  • no matter how/what, using addfieldprefix inside the templateDetails.xml and linking from a plugin doesn't work; EG addfieldprefix="Joomla\CMS\Plugin\EditorsXtd\Vimeo\Field"
  • I also found no documentation, stackoverflow or any resource about using namespaced custom form fields inside templateDetails.xml, I only found the libraries/namespacemap.php and seems only 4 types of items can use this system: if (!in_array($type, ['component', 'module', 'plugin', 'library'], true))

Open to any suggestion.


  • For those interested, probably mostly @Sharky, I made a PR to Joomla git in regards to this.
    – thednp
    Sep 30, 2020 at 12:42


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