From 530e5c686beebe576de2c19b48dfb773d55ba0ca Mon Sep 17 00:00:00 2001
From: Carson Full <carsonfull@gmail.com>
Date: Wed, 4 Sep 2024 16:29:16 -0500
Subject: [PATCH] Avoid duplicating __typename in generated EdgeQL

---
 integration-tests/lts/select.test.ts     | 17 +++++++++++++++++
 packages/generate/src/syntax/toEdgeQL.ts |  2 +-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/integration-tests/lts/select.test.ts b/integration-tests/lts/select.test.ts
index f44c05602..983a82e20 100644
--- a/integration-tests/lts/select.test.ts
+++ b/integration-tests/lts/select.test.ts
@@ -1119,6 +1119,23 @@ SELECT __scope_0_defaultPerson {
     >(true);
   });
 
+  test("polymorphic with explicit __typename is not duplicated", async () => {
+    const query = e.select(e.Movie.characters, (movie) => ({
+      __typename: movie.__type__.name,
+      ...e.is(e.Villain, { nemesis: true }),
+    }));
+
+    assert.equal(
+      query.toEdgeQL(),
+      `WITH
+  __scope_0_defaultPerson := DETACHED default::Movie.characters
+SELECT __scope_0_defaultPerson {
+  single __typename := __scope_0_defaultPerson.__type__.name,
+  [IS default::Villain].nemesis
+}`,
+    );
+  });
+
   test("polymorphic field in nested shape", async () => {
     const query = e.select(e.Movie, (movie) => ({
       title: true,
diff --git a/packages/generate/src/syntax/toEdgeQL.ts b/packages/generate/src/syntax/toEdgeQL.ts
index ee4d97a31..696241431 100644
--- a/packages/generate/src/syntax/toEdgeQL.ts
+++ b/packages/generate/src/syntax/toEdgeQL.ts
@@ -1398,7 +1398,7 @@ function shapeToEdgeQL(
   if (lines.length === 0 && injectImplicitId) {
     addLine("id");
   }
-  if (hasPolyEl) {
+  if (hasPolyEl && !seen.has("__typename")) {
     addLine("__typename := .__type__.name");
   }
   return keysOnly ? `{${lines.join(", ")}}` : `{\n${lines.join(",\n")}\n}`;