Check if dependencies exist as nodes.

Miguel Barão
1 parent 861d9ae5
Showing 1 changed file with 15 additions and 4 deletions Show diff stats
aprendizations/learnapp.py
@@ -40,6 +40,11 @@ async def bcrypt_hash_gen(new_pw):
 # ============================================================================
+class LearnException(Exception):
+    pass
+
+
+# ============================================================================
 # LearnApp - application logic
 # ============================================================================
 class LearnApp(object):
@@ -256,8 +261,8 @@ class LearnApp(object):
     #
     # Edges are obtained from the deps defined in the YAML file for each topic.
     # ------------------------------------------------------------------------
-    def populate_graph(self, conffile):
-        logger.info(f'Populating graph from:  {conffile}')
+    def populate_graph(self, conffile: str):
+        logger.info(f'Populating graph from:  {conffile}...')
         config = load_yaml(conffile)    # course configuration
         # default attributes that apply to the topics
@@ -275,7 +280,13 @@ class LearnApp(object):
         g.add_nodes_from(topics.keys())
         for tref, attr in topics.items():
-            g.add_edges_from((d, tref) for d in attr.get('deps', []))
+            for d in attr.get('deps', []):
+                if d not in g.nodes():
+                    logger.error(f'Topic "{tref}" depends on "{d}" but the '
+                                 f'latter does not exist')
+                    raise LearnException()
+                else:
+                    g.add_edge(d, tref)
             t = g.node[tref]  # get current topic node
             t['type'] = attr.get('type', 'topic')
@@ -302,7 +313,7 @@ class LearnApp(object):
     # Buils dictionary of question factories
     # ------------------------------------------------------------------------
     def make_factory(self):
-        logger.info('Building questions factory')
+        logger.info('Building questions factory...')
         factory = {}    # {'qref': QFactory()}
         g = self.deps
         for tref in g.nodes():