From 8e92be3e8b791187d8557fccd30ffc82feac5cd4 Mon Sep 17 00:00:00 2001
From: Ben Newman <ben@apollographql.com>
Date: Sat, 10 Oct 2020 13:21:24 -0400
Subject: [PATCH] Default args.offset to 0 in offsetLimitPagination. (#7141)

https://github.com/apollographql/apollo-client/issues/7135#issuecomment-706415063
---
 CHANGELOG.md                         |  7 +++++++
 src/utilities/policies/pagination.ts | 16 ++++++++++++----
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 88efbefa97e..a253ec9830f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,10 @@
+## Apollo Client 3.2.3
+
+## Improvements
+
+- Default `args.offset` to zero in `offsetLimitPagination`. <br/>
+  [@benjamn](https://github.com/benjamn) in [#7141](https://github.com/apollographql/apollo-client/pull/7141)
+
 ## Apollo Client 3.2.2
 
 ## Bug Fixes
diff --git a/src/utilities/policies/pagination.ts b/src/utilities/policies/pagination.ts
index 66f3429558c..8b7d8a23959 100644
--- a/src/utilities/policies/pagination.ts
+++ b/src/utilities/policies/pagination.ts
@@ -31,10 +31,18 @@ export function offsetLimitPagination<T = Reference>(
     keyArgs,
     merge(existing, incoming, { args }) {
       const merged = existing ? existing.slice(0) : [];
-      const start = args ? args.offset : merged.length;
-      const end = start + incoming.length;
-      for (let i = start; i < end; ++i) {
-        merged[i] = incoming[i - start];
+      if (args) {
+        // Assume an offset of 0 if args.offset omitted.
+        const { offset = 0 } = args;
+        for (let i = 0; i < incoming.length; ++i) {
+          merged[offset + i] = incoming[i];
+        }
+      } else {
+        // It's unusual (probably a mistake) for a paginated field not
+        // to receive any arguments, so you might prefer to throw an
+        // exception here, instead of recovering by appending incoming
+        // onto the existing array.
+        merged.push.apply(merged, incoming);
       }
       return merged;
     },