I created an entity in a module, using code. I generated skeletons with drupal console generate:entity:content (without bundles), and then added a datetime field to my TestFieldEntityItem.php, in baseFieldDefinitions().

$fields['test_date'] = BaseFieldDefinition::create('datetime')   ->setLabel(t('Test date'))   ->setDescription(t('Test.'))   ->setRevisionable(TRUE)   ->setSettings([     'datetime_type' => 'date'   ])   ->setDefaultValue('')   ->setDisplayOptions('view', [     'label' => 'above',     'type' => 'datetime_default',     'settings' => [       'format_type' => 'medium',     ],     'weight' => 14,   ])   ->setDisplayOptions('form', [     'type' => 'datetime_default',     'weight' => 14,   ])   ->setDisplayConfigurable('form', TRUE)   ->setDisplayConfigurable('view', TRUE); 

I installed my module, cleared the cache, reinstalled calendar and calendar_datetime modules, but when I try to add a view from a template, like the calendar module suggests, I can’t see any template matching my datetime field.

If I create a datetime field on this entity through the UI, it appears in view templates. What am I missing?

Inspecting the calendar code, I found the function that search datetime fields, in ViewsFieldTemplate.php. This function finds my field, but the field_info does not match isDateField() because of the argument property.

isDateField() wants ‘datetime’ as argument ID.

protected function isDateField($field_info) {   if (!empty($field_info['field']['id']) && $field_info['field']['id'] == 'field') {     if (!empty($field_info['argument']['id']) && $field_info['argument']['id'] == 'date') {       return TRUE;     }   }   return FALSE; } 

My field_info argument is ‘string’.

array (size=7)   'title' => ...   'help' => ...   'field' =>        'id' => string 'field' (length=5)   'argument' =>        'id' => string 'string' (length=6)   'filter' =>        'id' => string 'string' (length=6)   'sort' =>        'id' => string 'standard' (length=8)   'entity field' => string 'test_date' (length=4) 

So thanks to @4k4 answer, I tried to do the same as the working date field, and I created my own EntityViewsData (I tried hook_views_data_alter() first but the field was not present in input data)

namespace Drupalkabukis_testsEntity; use DrupalviewsEntityViewsData;  class TestEntityViewsData extends EntityViewsData {   public function getViewsData() {     $additionalData = [       'test_date' => [         'title' => new TranslatableMarkup('Birth date'),         'help' => new TranslatableMarkup('Birth date'),         'field' => [ 'id' => 'field' ],         'argument' => [ 'id' => 'date' ],         'filter' => [ 'id' => 'date' ],         'sort' => [ 'id' => 'date' ],         'entity field' => 'test_date',       ]     ];     $data['test_field_entity_field_data'] = array_merge($data['test_field_entity_field_data'], $additionalData);     return $data;   } } 

Now, the field appears in views template list ! However, the generated view is not working, I get the following error :

DrupalcalendarPluginviewsstyleCalendarStyle: A calendar date argument is required when using the calendar style, but it is missing or is not using the default date.