[4.0] Get categories from component

[SharkyKZ]

Pull Request for Issue #26157 (comment).

Summary of Changes

Get categories from component instead of using deprecated JCategories::getInstance().

Testing Instructions

Create a custom field for articles.
Assign to Uncategorised category.
Create an article. Select Uncategorised category.
Check that custom field appears in form.

Expected result AFTER applying this Pull Request

Works like before.

Documentation Changes Required

No.

[ghost]

I have tested this item ✅ successfully on 827a8d5

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[chmst]

I have tested this item ✅ successfully on 827a8d5

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/30613.}

[Quy]

RTC

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[wilsonge]

Will this still work on J3 style components that don't use services?

[SharkyKZ]

It should. Legacy components implement Joomla\CMS\Categories\CategoryServiceInterface.

joomla-cms/libraries/src/Extension/LegacyComponent.php

Lines 37 to 40 in a5cd87a

	class LegacyComponent
	implements ComponentInterface, MVCFactoryServiceInterface, CategoryServiceInterface, FieldsServiceInterface, RouterServiceInterface,
	TagServiceInterface
	{

Works with Weblinks 3.7.0.

[wilsonge]

Cool - thanks!