1 files changed, 32 insertions, 26 deletions
diff --git a/bsfs/graph/nodes.py b/bsfs/graph/nodes.py
index 91cbb5d..c6bd5d8 100644
--- a/bsfs/graph/nodes.py
+++ b/bsfs/graph/nodes.py
@@ -249,32 +249,38 @@ class Nodes():
         # add access controls to fetch
         fetch = self._ac.fetch_read(self.node_type, fetch)
 
-        # compose filter ast
-        filter = ast.filter.IsIn(self.guids) # pylint: disable=redefined-builtin
-        # add access controls to filter
-        filter = self._ac.filter_read(self.node_type, filter)
-
-        # validate queries
-        validate.Filter(self._backend.schema)(self.node_type, filter)
-        validate.Fetch(self._backend.schema)(self.node_type, fetch)
-
-        # process results, convert if need be
-        def triple_iter():
-            # query the backend
-            triples = self._backend.fetch(self.node_type, filter, fetch)
-            # process triples
-            for root, name, raw in triples:
-                # get node
-                node = Nodes(self._backend, self._ac, self.node_type, {root})
-                # get path
-                path, tail = name2path[name]
-                # covert raw to value
-                if isinstance(tail.range, bsc.Node):
-                    value = Nodes(self._backend, self._ac, tail.range, {raw})
-                else:
-                    value = raw
-                # emit triple
-                yield node, path, value
+        if len(self._guids) == 0:
+            # shortcut: no need to query; no triples
+            # FIXME: if the Fetch query can given by the user, we might want to check its validity
+            def triple_iter():
+                return []
+        else:
+            # compose filter ast
+            filter = ast.filter.IsIn(self.guids) # pylint: disable=redefined-builtin
+            # add access controls to filter
+            filter = self._ac.filter_read(self.node_type, filter) # type: ignore [assignment]
+
+            # validate queries
+            validate.Filter(self._backend.schema)(self.node_type, filter)
+            validate.Fetch(self._backend.schema)(self.node_type, fetch)
+
+            # process results, convert if need be
+            def triple_iter():
+                # query the backend
+                triples = self._backend.fetch(self.node_type, filter, fetch)
+                # process triples
+                for root, name, raw in triples:
+                    # get node
+                    node = Nodes(self._backend, self._ac, self.node_type, {root})
+                    # get path
+                    path, tail = name2path[name]
+                    # covert raw to value
+                    if isinstance(tail.range, bsc.Node):
+                        value = Nodes(self._backend, self._ac, tail.range, {raw})
+                    else:
+                        value = raw
+                    # emit triple
+                    yield node, path, value
 
         # simplify by default
         view_kwargs['node'] = view_kwargs.get('node', len(self._guids) != 1)