public function toStorageFieldDefinition(FieldDefinition $fieldDef, StorageFieldDefinition $storageDef) { if (isset($fieldDef->fieldTypeConstraints->fieldSettings['isISBN13'])) { $storageDef->dataInt1 = $fieldDef->fieldTypeConstraints->fieldSettings['isISBN13']; } else { $storageDef->dataInt1 = 1; } $storageDef->dataText1 = $fieldDef->defaultValue->data; }