Fix l7rule API handling of None updates

The current l7rule API does not properly handle
clearing/reseting values on update.

This patch corrects this to appropriately handle None/null updates
to the l7rule parameters.

Conflicts:
    octavia/tests/functional/api/v2/test_l7rule.py

Story: 2005374
Task: 36023

Change-Id: I4e8007ff98f585ce6622f7128ecdd53cdfa926a7
(cherry picked from commit e4e7b4a880)
(cherry picked from commit 55b04f279b)
(cherry picked from commit e0913562de)

octavia/api/v2/controllers/l7rule.py

@@ -198,6 +198,11 @@ class L7RuleController(base.BaseController):
         l7rule = l7rule_.rule
         context = pecan.request.context.get('octavia_context')
         db_l7rule = self._get_db_l7rule(context.session, id)
+
+        # Handle the invert unset
+        if l7rule.invert is None:
+            l7rule.invert = False
+
         new_l7rule = db_l7rule.to_dict()
         new_l7rule.update(l7rule.to_dict())
         new_l7rule = data_models.L7Rule.from_dict(new_l7rule)

octavia/common/validate.py

@@ -104,6 +104,8 @@ def regex(regex):
 # L7 rules must be internally consistent.
 def l7rule_data(l7rule):
     """Raises an error if the l7rule given is invalid in some way."""
+    if not l7rule.value:
+        raise exceptions.InvalidL7Rule(msg=_('L7 rule type requires a value'))
     if l7rule.type == constants.L7RULE_TYPE_HEADER:
         if not l7rule.key:
             raise exceptions.InvalidL7Rule(msg='L7 rule type requires a key')