From 986aac5715965b5907bc21ffa8c60dcfc7c47da1 Mon Sep 17 00:00:00 2001
From: Yaacov Rydzinski <yaacovCR@gmail.com>
Date: Thu, 9 Nov 2023 14:47:05 +0200
Subject: [PATCH 1/2] fix(incremental): fix loop

---
 src/execution/IncrementalPublisher.ts | 30 +++++++++++++++------------
 1 file changed, 17 insertions(+), 13 deletions(-)

diff --git a/src/execution/IncrementalPublisher.ts b/src/execution/IncrementalPublisher.ts
index 161c90553c..e8d3b83fd9 100644
--- a/src/execution/IncrementalPublisher.ts
+++ b/src/execution/IncrementalPublisher.ts
@@ -609,27 +609,31 @@ export class IncrementalPublisher {
     deferredGroupedFieldSetRecord: DeferredGroupedFieldSetRecord,
   ): IncrementalDeferResult {
     const { data, deferredFragmentRecords } = deferredGroupedFieldSetRecord;
-    let maxLength = deferredFragmentRecords[0].path.length;
-    let maxIndex = 0;
-    for (let i = 1; i < deferredFragmentRecords.length; i++) {
-      const deferredFragmentRecord = deferredFragmentRecords[i];
+    let maxLength: number | undefined;
+    let recordWithLongestPath: DeferredFragmentRecord | undefined;
+    for (const deferredFragmentRecord of deferredFragmentRecords) {
+      if (deferredFragmentRecord.id === undefined) {
+        continue;
+      }
       const length = deferredFragmentRecord.path.length;
-      if (length > maxLength) {
+      if (maxLength === undefined || length > maxLength) {
         maxLength = length;
-        maxIndex = i;
+        recordWithLongestPath = deferredFragmentRecord;
       }
     }
-    const recordWithLongestPath = deferredFragmentRecords[maxIndex];
-    const longestPath = recordWithLongestPath.path;
-    const subPath = deferredGroupedFieldSetRecord.path.slice(
-      longestPath.length,
-    );
-    const id = recordWithLongestPath.id;
+    const subPath = deferredGroupedFieldSetRecord.path.slice(maxLength);
+    // safe because `id` is always defined once the fragment has been released
+    // as pending and at least one fragment has been completed, so must have been
+    // released as pending
+    // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+    const id = recordWithLongestPath!.id;
     const incrementalDeferResult: IncrementalDeferResult = {
       // safe because `data``is always defined when the record is completed
       // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
       data: data!,
-      // safe because `id` is defined once the fragment has been released as pending
+      // safe because `id` is always defined once the fragment has been released
+      // as pending and at least one fragment has been completed, so must have been
+      // released as pending
       // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
       id: id!,
     };

From 969f4173dd7b241c885c5920fd4e7b23961e1e0a Mon Sep 17 00:00:00 2001
From: Yaacov Rydzinski <yaacovCR@gmail.com>
Date: Thu, 9 Nov 2023 21:45:46 +0200
Subject: [PATCH 2/2] integrate suggestion from review

---
 src/execution/IncrementalPublisher.ts | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/src/execution/IncrementalPublisher.ts b/src/execution/IncrementalPublisher.ts
index e8d3b83fd9..760043c78b 100644
--- a/src/execution/IncrementalPublisher.ts
+++ b/src/execution/IncrementalPublisher.ts
@@ -610,23 +610,19 @@ export class IncrementalPublisher {
   ): IncrementalDeferResult {
     const { data, deferredFragmentRecords } = deferredGroupedFieldSetRecord;
     let maxLength: number | undefined;
-    let recordWithLongestPath: DeferredFragmentRecord | undefined;
+    let idWithLongestPath: string | undefined;
     for (const deferredFragmentRecord of deferredFragmentRecords) {
-      if (deferredFragmentRecord.id === undefined) {
+      const id = deferredFragmentRecord.id;
+      if (id === undefined) {
         continue;
       }
       const length = deferredFragmentRecord.path.length;
       if (maxLength === undefined || length > maxLength) {
         maxLength = length;
-        recordWithLongestPath = deferredFragmentRecord;
+        idWithLongestPath = id;
       }
     }
     const subPath = deferredGroupedFieldSetRecord.path.slice(maxLength);
-    // safe because `id` is always defined once the fragment has been released
-    // as pending and at least one fragment has been completed, so must have been
-    // released as pending
-    // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-    const id = recordWithLongestPath!.id;
     const incrementalDeferResult: IncrementalDeferResult = {
       // safe because `data``is always defined when the record is completed
       // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
@@ -635,7 +631,7 @@ export class IncrementalPublisher {
       // as pending and at least one fragment has been completed, so must have been
       // released as pending
       // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-      id: id!,
+      id: idWithLongestPath!,
     };
 
     if (subPath.length > 0) {