Allow None for Version.is_head and Version.is_complete_history

src/linkahead/common/versioning.py

@@ -103,8 +103,8 @@ class Version():
     def __init__(self, id: Optional[str] = None, date: Optional[str] = None,
                  username: Optional[str] = None, realm: Optional[str] = None,
                  predecessors: Optional[List[Version]] = None, successors: Optional[List[Version]] = None,
-                 is_head: Union[bool, str] = False,
-                 is_complete_history: Union[bool, str] = False):
+                 is_head: Union[bool, str, None] = False,
+                 is_complete_history: Union[bool, str, None] = False):
         """Typically the `predecessors` or `successors` should not "link back" to an existing Version
 object."""
         self.id = id
@@ -210,18 +210,9 @@ object."""
             p) for p in xml if p.tag.lower() == "predecessor"]
         successors = [Version.from_xml(s)
                       for s in xml if s.tag.lower() == "successor"]
-        is_head = xml.get("head")
-        if is_head is None:
-            raise ValueError(f"Version head is missing from xml:{str(xml)}")
-
-        is_complete_history = xml.get("completeHistory")
-        if is_complete_history is None:
-            raise ValueError(
-                f"Version completeHistory is missing from xml:{str(xml)}")
-
         return Version(id=xml.get("id"), date=xml.get("date"),
-                       is_head=is_head,
-                       is_complete_history=is_complete_history,
+                       is_head=xml.get("head"),
+                       is_complete_history=xml.get("completeHistory"),
                        username=xml.get("username"), realm=xml.get("realm"),
                        predecessors=predecessors, successors=successors)