Allow linking to referenced entities: add `url` property to `EntityReferenceItem::propertyDefinitions()`
>>> [!note] Migrated issue
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<!-- Migrated from issue #3555413. -->
Reported by: [lauriii](https://www.drupal.org/user/1078742)
Related to !292
>>>
<h3 id="overview">Overview</h3>
<p><del><span class="drupalorg-gitlab-issue-link drupalorg-gitlab-link-wrapper"><a href="https://git.drupalcode.org/project/canvas/-/work_items/3545859" class="drupalorg-gitlab-link">https://git.drupalcode.org/project/canvas/-/work_items/3545859</a></span> introduced <code>HostEntityUrlPropSource</code> but it supports only the host entity. However, there are many valid use cases to link to entities that are other than the host entity; for example, if you are rendering tags, you may want to link to the taxonomy term canonical page to list more content with the same tag or you may want to link to the users profile.</del></p>
<p>The <em>end user goal</em> makes sense, the proposed technical implementation does not, and led this issue into some chaos due to how <span class="drupalorg-gitlab-issue-link drupalorg-gitlab-link-wrapper"><a href="https://git.drupalcode.org/project/canvas/-/work_items/3545859" class="drupalorg-gitlab-link">https://git.drupalcode.org/project/canvas/-/work_items/3545859</a></span> landed. Fortunately, we quickly recovered from the chaos by having conversations between @Wim Leers, @lauriii, @phenaproxima and @effulgentsia. 🤝</p>
<h3 id="proposed-resolution">Proposed resolution</h3>
<p><del>Expand this feature to ensure <em>all</em> entities that may be accessed in content templates, not just the host entity, can be used in link props.</del></p>
<p>See <span class="drupalorg-gitlab-issue-link drupalorg-gitlab-link-wrapper"><a href="https://git.drupalcode.org/project/canvas/-/work_items/3545859" class="drupalorg-gitlab-link">https://git.drupalcode.org/project/canvas/-/work_items/3545859</a></span>.</p>
<h3 id="ui-changes">User interface changes</h3>
<p>Tested while editing the <code>ContentTemplate</code> for article <code>Node</code>s, using the <code>type: string, format: uri-reference</code> prop in the "all props" test SDC:</p>
<dl>
<dt>Before</dt>
<dd><img src="https://www.drupal.org/files/issues/2025-11-04/before.gif"></dd>
<dt>After</dt>
<dd><img src="https://www.drupal.org/files/issues/2025-11-04/after.gif"></dd>
</dl>
issue