MapItem violates FieldItemInterface::schema()'s contract - breaks widgets

How do widgets rely on that? Anything on widgets can be overridden to do whatever you want? Widgets like Paragraphs and IEF have litte/nothing to do with the property/schema structure.

I agree that it does violate the documentation/description there, but it does reflect how it really behaves?

The only way to respect that documentation would be to change MapItem so that it contains a value map property, but that would obviously be a bigger API change.

It think it's this which causes a crash when installing an entity type using this field type (in my case, as a bundle field coming from a Commerce bundle plugin):

Error: Call to a member function isRequired() on null in             [error]
Drupal\Core\Entity\Sql\SqlContentEntityStorageSchema->getDedicatedTableSchema()
(line 1846 of
core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchema.php)

Quoting @tstoeckler at #2906600-7: FieldItemList::equals() doesn't work correctly for computed fields with custom storage:

2. Map fields will always be considered equal regardless of their values due to #2887105: MapItem violates FieldItemInterface::schema()'s contract - breaks widgets. Note that even though I consider that a bug I don't think it makes sense to block this (or anything) on that as @Berdir does not consider it a bug, so regardless where we collectively come down on this I don't think it will be fixed anytime soon.

Confirming #4. Detail at #2895532-124: @DataType=map cannot be normalized, affects @FieldType=link, @FieldType=map.

There is another problem with that definition removal. The base fields of "map" type can't be uninstalled.

Definition:

$fields['contribution_statistics'] = BaseFieldDefinition::create('map')
      ->setLabel(t('Contribution statistics'))
      ->setDescription(t('The contribution statistics of source file.'))
      ->setRequired(TRUE)
      ->setDisplayConfigurable('form', FALSE)
      ->setDisplayConfigurable('view', FALSE);

Hook update which tries to uninstall it:

  $definition_update_manager = \Drupal::entityDefinitionUpdateManager();
  if ($field_definition = $definition_update_manager->getFieldStorageDefinition('contribution_statistics', 'my_entity_type_id')) {
    $definition_update_manager->uninstallFieldStorageDefinition($field_definition);
  }

This hook update fails with

>  [error]  Call to a member function isRequired() on null 

. This is because isRequired() checks for !empty($this->definition['required']), but $this->definition is an empty array, since there is no definition!

I've managed to fix this by rollback the definition removal and run the update, which ended successfully. I think this issue needs more attention.

Attach the patch which solve my problem.

@tstoeckler there is no nothing special. Simple content entity type + definition I've provided. It can't be uninstalled. It fails when check its property "is required", but there is no property.

I can't test your solution right now, since I bypass this error by temporary rollback definition removal. But this can be easily reproduced with just 1 base field installed on entity and trying to uninstall it then via hook_update_N().

Actually I copy-pasted all the code that reproduces bug as it is.

Here is another impact this issue is having: #3145076: [backport] MapItem base fields cannot be uninstalled.

Edit: I can see this was mentioned in #12.

This issue is being reviewed by the kind folks in Slack, #needs-review-queue-initiative. We are working to keep the size of Needs Review queue [2700+ issues] to around 400 (1 month or less), following Review a patch or merge request as a guide.

Seems the last patch had some failures in D8 (triggered for D10)

Think we will need a test case also to show the issue.