FieldPath refers to a field in a document. The path may consist of a single field name (referring to a top-level field in the document), or a list of field names (referring to a nested field in the document).
FieldPath by providing field names. If more than one field name is provided, the path will point to a nested field in a document.
A list of field names.
Value may be repeated.
documentId() returns admin.firestore.FieldPath
Returns a special sentinel
FieldPath to refer to the ID of a document. It can be used in queries to sort or filter by the document ID.