Problem/Motivation
I am working on developing a diff UI plugin for Taxonomy Terms and came across an issue in which the comparison table for taxonomy term
can not be rendered.
Steps to reproduce
Create a new route in which the path is '/taxonomy/term/{taxonomy_term}/revisions/view/{left_revision}/{right_revision}/{filter}' by a custom module.
In the controller function, use following codes to build the comparison table.
$build = $this->compareEntityRevisions($route_match, $left_revision, $right_revision, $filter);
When I access following URL:
/taxonomy/term/230/revisions/view/236/237/visual_inline
a fatal PHP error caused said:
Notice: Undefined index: full in Drupal\diff\Plugin\diff\Layout\VisualInlineDiffLayout->build() (line 159 of /usr/local/var/www/govCMS8/docroot/modules/contrib/diff/src/Plugin/diff/Layout/VisualInlineDiffLayout.php)
Proposed resolution
After debugging the codes, I am aware that this issue is caused by line 139 in /src/Plugin/diff/Layout/VisualInlineDiffLayout.php
// Get all view modes for entity type.
$view_modes = $this->entityDisplayRepository->getViewModeOptionsByBundle($entity->getEntityTypeId(), $entity->bundle());
The problem is that there is no display mode for a taxonomy bundle by default until you go to the display setting page (/admin/structure/taxonomy/manage/{vocabulary name}/overview/display) and save the setting for this vocabulary (bundle).
So $view_modes will be null if you haven't saved the display setting for a vocabulary.
The solution could be using the default display mode for an entity bundle that hasn't had any view display configuration yet. The updated code is
// Get all view modes for entity type.
$view_modes = $this->entityDisplayRepository->getViewModeOptionsByBundle($entity->getEntityTypeId(), $entity->bundle());
if (empty($view_modes)) {
// There is no any view modes for the entity bundle specified.
// Use the default view mode of the entity instead.
$view_modes = $this->entityDisplayRepository->getViewModeOptions($entity->getEntityTypeId());
}
This could happen to any entity types other than Node, not just Taxonomy Terms.
Remaining tasks
Create test script.
User interface changes
N/A
API changes
N/A
Data model changes
N/A
