I have a custom entity (Person) with these fields: ID, nom, prenom, telephoneportable, estactive, userID, created, changed. I created it with baseFieldDefinitions.

I want to have a computed field nomprenom = nom .” “.prenom
Here is the corresponding code:

$fields['nomprenom'] = BaseFieldDefinition::create('string')     ->setLabel(t('Nom et Prénom'))     ->setComputed(TRUE)     ->setClass('DrupalassociationNomPrenom');   

The code of class ‘NomPrenom’ is here:

/**  * @file  * Contains DrupalassociationNomPrenom.  */  namespace Drupalassociation;  use DrupalComponentUtilityString; use DrupalCoreTypedDataDataDefinitionInterface; use DrupalCoreTypedDataTypedDataInterface; use DrupalCoreTypedDataTypedData;  /**  * A computed property for defining 'Nom Prénom'.  */ class NomPrenom extends TypedData {    /**    * Cached processed value.    *    * @var string|null    */   protected $processed = NULL;    /**    * Implements DrupalCoreTypedDataTypedDataInterface::getValue().    */   public function getValue($langcode = NULL) {     if ($this->processed !== NULL) {       return $this->processed;     }      $this->processed = $this->get('nom')->value ." ". $this->get('prenom')->value;     return $this->processed;   }    /**    * Implements DrupalCoreTypedDataTypedDataInterface::setValue().    */   public function setValue($value, $notify = TRUE) {     $this->processed = $value;      // Notify the parent of any changes.     if ($notify && isset($this->parent)) {       $this->parent->onChange($this->name);     }   }  }   

When I try to add a new Person, I get a PHP Fatal error:

Call to undefined method DrupalassociationNomPrenom::setLangcode()

Why?