Pull Request resolves #47609

• I read the Generative AI policy and my contribution is either not created with the help of AI or is compatible with the policy and GNU/GPL 2 or later.

Summary of Changes

This PR fixes a regression introduced in Joomla 5.4 where saving an article that has tags creates a duplicate row in the #__ucm_content table on every save.

The fix modifies a query in TagsHelper::postStore() (libraries/src/Helper/TagsHelper.php) to look up existing UCM records directly from the #__ucm_content table instead of the deprecated #__ucm_base table.

Root Cause

In Joomla 5.4, UCM architecture was deprecated and the call to storeUcmBase() was removed from CoreContent::store(). This means articles created after Joomla 5.4 no longer get a row in the #__ucm_base table.

However, TagsHelper::postStore() was still querying #__ucm_base to determine whether an existing #__ucm_content row exists for the article. Since new articles have no entry in #__ucm_base, the query always returns null. TagsHelper interprets this as 'no UCM record exists yet' and inserts a brand new duplicate row into #__ucm_content on every save.

Approach

This PR takes a different approach compared to existing PRs for this issue:
Stop querying the deprecated table entirely.

By querying #__ucm_content directly the fix:
(1) Is immune to orphaned #__ucm_base rows.
(2) Does not need to keep #__ucm_base and #__ucm_content in sync.
(3) Aligns with the deprecation roadmap (dropping #__ucm_base in 7.0).

However,
#__ucm_content is a big table with many columns so querying is expensive ( performance wise).

Testing Instructions

(1) Create an article and assign a tag to it.
(2) Click on save, wait for the page to reload and click on save again.

Actual result BEFORE applying this Pull Request

In the #__ucm_content table, for each click on save, a new entry is created in the table. No entry for the item is generated in #__ucm_base.

Expected result AFTER applying this Pull Request

A single entry is created in #__ucm_content and for successive saves of the articles the same entry is updated.
No duplicates are created.

Link to documentations

Please select:

• Documentation link for guide.joomla.org:

• No documentation changes for guide.joomla.org needed

• Pull Request link for manual.joomla.org:

• No documentation changes for manual.joomla.org needed