Add variables to generated event filter and event object

Event types can not only contain properties, but also variables. For example the ConditionType, which is the foundation of Alarms and Conditions, contains variables. Add the variables to the generated event filter and event object.

asyncua/common/events.py

@@ -125,8 +125,10 @@ async def select_clauses_from_evtype(evtypes):
     clauses = []
     selected_paths = []
     for evtype in evtypes:
-        for prop in await get_event_properties_from_type_node(evtype):
-            browse_name = await prop.read_browse_name()
+        event_props_and_vars = await get_event_properties_from_type_node(evtype)
+        event_props_and_vars.extend(await get_event_variables_from_type_node(evtype))
+        for node in event_props_and_vars:
+            browse_name = await node.read_browse_name()
             if browse_name not in selected_paths:
                 op = ua.SimpleAttributeOperand()
                 op.AttributeId = ua.AttributeIds.Value
@@ -180,6 +182,22 @@ async def get_event_properties_from_type_node(node):
     return properties
 
 
+async def get_event_variables_from_type_node(node):
+    variables = []
+    curr_node = node
+    while True:
+        variables.extend(await curr_node.get_variables())
+        if curr_node.nodeid.Identifier == ua.ObjectIds.BaseEventType:
+            break
+        parents = await curr_node.get_referenced_nodes(
+            refs=ua.ObjectIds.HasSubtype, direction=ua.BrowseDirection.Inverse, includesubtypes=True
+        )
+        if len(parents) != 1:  # Something went wrong
+            return None
+        curr_node = parents[0]
+    return variables
+
+
 async def get_event_obj_from_type_node(node):
     """
     return an Event object from an event type node
@@ -198,9 +216,11 @@ async def get_event_obj_from_type_node(node):
             async def init(self):
                 curr_node = node
                 while curr_node.nodeid.Identifier != parent_identifier:
-                    for prop in await curr_node.get_properties():
-                        name = (await prop.read_browse_name()).Name
-                        val = await prop.read_data_value()
+                    node_props_and_vars = await curr_node.get_properties()
+                    node_props_and_vars.extend(await curr_node.get_variables())
+                    for field in node_props_and_vars:
+                        name = (await field.read_browse_name()).Name
+                        val = await field.read_data_value()
                         self.add_property(name, val.Value.Value, val.Value.VariantType)
                     parents = await curr_node.get_referenced_nodes(refs=ua.ObjectIds.HasSubtype,
                                                                    direction=ua.BrowseDirection.Inverse,