added child resource lookup to pagination base resource

ordr2/resources/base.py

@@ -30,8 +30,13 @@ class BaseResource(object):
 
 
     def __getitem__(self, key):
-        klass = self.nodes[key]
-        return klass(key, self)
+        klass = self.nodes.get(key, None)
+        if klass:
+            return klass(key, self)
+        try:
+            return super().__getitem__(key)
+        except AttributeError:
+            raise KeyError()
 
 
     @classmethod
@@ -210,3 +215,10 @@ class PaginationResourceMixin(object):
         params = self.query_params(*args, **kwargs)
         return self.request.resource_url(self, query=params)
 
+
+    def __getitem__(self, key):
+        model = self.request.dbsession.query(self.sql_model_class).get(key)
+        if not model:
+            raise KeyError()
+        return self.child_resource_class.from_sqla(model, self)
+