[BEAM-12696] Update NewTaggedExternal to not require inputs (apache#1…

…5266)
ryanthompson591 · Aug 10, 2021 · 8099ee2 · 8099ee2
1 parent 152f74b
commit 8099ee2
Showing 1 changed file with 7 additions and 1 deletion.
diff --git a/sdks/go/pkg/beam/core/graph/edge.go b/sdks/go/pkg/beam/core/graph/edge.go
@@ -387,7 +387,13 @@ func NewTaggedExternal(g *Graph, s *Scope, payload *Payload, ins []*Inbound, out
 	edge.Op = External
 	edge.Payload = payload
 
-	windowingStrategy := inputWindow([]*Node{ins[0].From})
+	var windowingStrategy *window.WindowingStrategy
+	if len(ins) == 0 {
+		windowingStrategy = window.DefaultWindowingStrategy()
+	} else {
+		windowingStrategy = inputWindow([]*Node{ins[0].From})
+	}
+
 	for _, o := range outs {
 		o.To.w = windowingStrategy
 		o.To.bounded = bounded