Apply formatters and widgets to Taxonomy Term base fields

Yay !
Adjusted issue summary, this does not turn the base fields into configurable fields, only makes them use widgets / formatters.

side note: I'd happily leave it to someone to update the summaries on #2225371: Apply formatters and widgets to Custom Block base fields and #2225399: Apply formatters and widgets to Feed base fields similarly ;-)

Assigning to myself to work on this during the Drupal Developer Days Szeged sprint.

Fixed the test failures.

1. +++ b/core/modules/forum/config/entity.form_display.taxonomy_term.forums.default.yml
   @@ -3,11 +3,6 @@ targetEntityType: taxonomy_term
   -content:
   -  name:
   -    weight: -5
   -  description:
   -    weight: 0
   

   Hm, we still want to provide a 'content' section with 'name' and 'description' entries in the display shipped in default config.
   We just want to extend each of those entries with properties for "being displayed by a widget / formatter" - see how it appears in a real-life entity.form_display.taxonomy_term.forums.default.yml file after the patch (and after submiting the corresponding "Manage Form" screen)

2. +++ b/core/modules/taxonomy/lib/Drupal/taxonomy/TermViewBuilder.php
   @@ -19,30 +19,9 @@ class TermViewBuilder extends EntityViewBuilder {
   +    /** @var \Drupal\taxonomy\TermInterface $entity */
   

   Unrelated / not needed ?
   (I know we put those more and more, still hate them ;-)

Thanks for the review @yched!

Regarding your first point, this might be indicative of another bug, but we had to remove this to prevent ContainerFormController from breaking:

Widget instantiation in EntityFormDisplay::getRenderer():

    // Instantiate the widget object from the stored display properties.
    if (($configuration = $this->getComponent($field_name)) && isset($configuration['type']) && ($definition = $this->getFieldDefinition($field_name))) {
      $widget = $this->pluginManager->getInstance(array(
        'field_definition' => $definition,
        'form_mode' => $this->originalMode,
        // No need to prepare, defaults have been merged in setComponent().
        'prepare' => FALSE,
        'configuration' => $configuration
      ));
    }

EntityDisplayBase::getComponent():

  /**
   * {@inheritdoc}
   */
  public function getComponent($name) {
    return isset($this->content[$name]) ? $this->content[$name] : NULL;
  }

If we left the content section in, then $this->content['name'|'description'] would no longer be empty but contain weight. This caused the widget for the fields to fail initialization, since getComponent() returned a configuration array with just weight, none of the other properties like type, and the widgets for name and description ended up being NULL.

I have removed the @var type hinting mentioned in your second point.

Forgot to attach interdiff in previous comment.

@mr.baileys : that's because the entries should turn from "entries for an 'extra field'" to "entries for a field rendered by a widget" - i.e, they should now have a 'type' property, which is the name of the widget (and optionnally, not needed in our case here, a 'settings' property).

Something like :
core/modules/forum/config/entity.form_display.taxonomy_term.forums.default.yml

 content:
   name:
+    type: string
     weight: -5
   description:
+    type: text_textfield
     weight: 0

#1875974: Abstract 'component type' specific code out of EntityDisplay will make the difference between the two kind of entries (extra fields / fields using a widget) more explicit, but for now that's how it works.

Thanks @yched! Fixed with help from Wim Leers and swentel.

Oh wow, this was fun to debug

Hey, so this is a review of @swentel's patch in #14 (because @Wim is too fast for me... ;) ) Will reapply patch and double check for #15.

Patch applies fine and form display and rendering of taxonomy term look identical to pre-patch.

Here are screenshots of working formatters:

Confirmation: Patch #15 works just as well.

RTBC pending test result.

Needs a reroll

git ac https://drupal.org/files/issues/2225431-15.patch
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 25369  100 25369    0     0  19986      0  0:00:01  0:00:01 --:--:-- 23360
error: patch failed: core/modules/taxonomy/taxonomy.module:135
error: core/modules/taxonomy/taxonomy.module: patch does not apply

Previous patch was missing changes from #14/#15. Here is the correct re-roll.

Test is green, since it is just a reroll (and currently applies), I'm moving it to RTBC.

Committed/pushed to 8.x, thanks!