Filtering by the optinal attribute without any defined value considered

mpewui.py

@@ -272,6 +272,9 @@ def __init__(self, qdict):
 					self.fltopts[k] = val
 				else:
 					# Filter meaning: the option should present with any (non-None) value
+					if k[-1] == '*':
+						assert False, 'Only defined attributes can be optional: ' + k
+						k = k[:-1]
 					self.fltopts[k] = None
 		# # Fetch the kind of items to be shown
 		# self.kind = qdict.get(UiResOpt.kind.name)  #pylint: disable=E1101
@@ -460,7 +463,7 @@ def root(cmd):
 		# Parse URL parameters and form the UI command parameters
 		try:
 			resopts = ResultOptions(bottle.request.query)
-		except (KeyError, ValueError) as err:
+		except (KeyError, ValueError, AssertionError) as err:
 			# 400  - Bad Request
 			# 415  - Unsupported Media Type
 			bottle.response.status = 400

views/restapi.md

@@ -58,9 +58,9 @@
 <p>Query <strong>examples</strong>:
 <ul>
   <li>
-    Show tasks with their jobs having <var>rcode=-15</var> if exists, <var>1.5 sec &le; duration &lt; 3600 sec</var> and <var>category</var> attribute might present with any value:
+    Show tasks with their jobs having <var>rcode=-15</var> if exists, <var>1.5 sec &le; duration &lt; 3600 sec</var> and <var>cat1 &le; category &lt; cat5 </var> if exists:
     <pre>
-      http://localhost:8080/tasks?flt=rcode*:-15|duration:1.5..3600|category*
+      http://localhost:8080/tasks?flt=rcode*:-15|duration:1.5..3600|category*=cat1..cat5
     </pre>
   </li>
   <li>