The unique field validation works for EntityForm, even when you want to create a media entity, but. the media library uses the class FileUploadForm, that class has not a method getEntity, and we get an error from the media library using the unique field.
Error: Call to undefined method Drupal\media_library\Form\FileUploadForm::getEntity() in unique_content_field_validation_validate_unique() (line 231 of /app/web/modules/contrib/unique_content_field_validation/unique_content_field_validation.module)
Install the module unique_field_ajax
Go to structure/media/fields create a new text field named "test"
Enable unique value on that field
Go to structure/ content types, add a new field named media to the basic content type
Go to structure/ content types / basic page, manage form display, the new field "media" should use the widget "Media Library"
Go to node/add/page, try to add a media using the media library and the unique field in the media library form.
Fixed
2.0
Code
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It's likely this issue predates Contrib.social: some issue and comment data are missing.
I have use this patch for more than a year and it is working ok.
Reroll latest patch for 2.x and checking if there is a entity to avoid null references for getEntityTypeId().
Automatically closed - issue fixed for 2 weeks with no activity.