From ae72f1afbe857e508b5a19edb3e22959c5b80a43 Mon Sep 17 00:00:00 2001
From: Nigel Sampson <nigel.sampson@pushpay.com>
Date: Tue, 3 Dec 2019 15:08:51 +1300
Subject: [PATCH] Don't append __typename if it's already being selection
 (#1221)

---
 .../Stitching/Utilities/ExtractFieldQuerySyntaxRewriter.cs | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/Stitching/Stitching/Utilities/ExtractFieldQuerySyntaxRewriter.cs b/src/Stitching/Stitching/Utilities/ExtractFieldQuerySyntaxRewriter.cs
index 9335096b171..74b96e455e5 100644
--- a/src/Stitching/Stitching/Utilities/ExtractFieldQuerySyntaxRewriter.cs
+++ b/src/Stitching/Stitching/Utilities/ExtractFieldQuerySyntaxRewriter.cs
@@ -179,7 +179,12 @@ protected override SelectionSetNode RewriteSelectionSet(
 
             RemoveDelegationFields(current, context, selections);
             AddDependencies(context.TypeContext, selections, dependencies);
-            selections.Add(CreateField(WellKnownFieldNames.TypeName));
+
+            if (!selections.OfType<FieldNode>().Any(n => n.Name.Value == WellKnownFieldNames.TypeName))
+            {
+                selections.Add(CreateField(WellKnownFieldNames.TypeName));
+            }
+            
             current = current.WithSelections(selections);
             current = base.RewriteSelectionSet(current, context);
             current = OnRewriteSelectionSet(current, context);