The method will check for custom fields if given $sortClause implements
CustomFieldInterface. With optional parameter $name specific field from
field type's Indexable implementation can be targeted.
Will return null if no sortable field is found.
public getSortFieldName ( eZ\Publish\API\Repository\Values\Content\Query\SortClause $sortClause, string $contentTypeIdentifier, string $fieldDefinitionIdentifier, null | string $name = null ) : null | string | ||
$sortClause | eZ\Publish\API\Repository\Values\Content\Query\SortClause | |
$contentTypeIdentifier | string | |
$fieldDefinitionIdentifier | string | |
$name | null | string | |
return | null | string |