From a6d66e941d563192dbbc1b319dc2059ff9978fe2 Mon Sep 17 00:00:00 2001
From: Lenz Weber-Tronic <lorenz.weber-tronic@apollographql.com>
Date: Mon, 27 Nov 2023 12:18:00 +0100
Subject: [PATCH] ensure `defaultContext` is also used for mutations and
 subscriptions

---
 .changeset/quick-hats-marry.md           |  5 +++++
 src/core/QueryManager.ts                 |  6 ++----
 src/core/__tests__/QueryManager/index.ts | 11 ++++++++---
 3 files changed, 15 insertions(+), 7 deletions(-)
 create mode 100644 .changeset/quick-hats-marry.md

diff --git a/.changeset/quick-hats-marry.md b/.changeset/quick-hats-marry.md
new file mode 100644
index 00000000000..2667f0a9750
--- /dev/null
+++ b/.changeset/quick-hats-marry.md
@@ -0,0 +1,5 @@
+---
+"@apollo/client": patch
+---
+
+ensure `defaultContext` is also used for mutations and subscriptions
diff --git a/src/core/QueryManager.ts b/src/core/QueryManager.ts
index e19cfdd71a3..98ab4d1d1f4 100644
--- a/src/core/QueryManager.ts
+++ b/src/core/QueryManager.ts
@@ -8,7 +8,6 @@ import { equal } from "@wry/equality";
 import type { ApolloLink, FetchResult } from "../link/core/index.js";
 import { execute } from "../link/core/index.js";
 import {
-  compact,
   hasDirectives,
   isExecutionPatchIncrementalResult,
   isExecutionPatchResult,
@@ -1161,9 +1160,7 @@ export class QueryManager<TStore> {
     return asyncMap(
       this.getObservableFromLink(
         linkDocument,
-        // explicitly a shallow merge so any class instances etc. a user might
-        // put in here will not be merged into each other.
-        compact(this.defaultContext, options.context),
+        options.context,
         options.variables
       ),
 
@@ -1676,6 +1673,7 @@ export class QueryManager<TStore> {
   private prepareContext(context = {}) {
     const newContext = this.localState.prepareContext(context);
     return {
+      ...this.defaultContext,
       ...newContext,
       clientAwareness: this.clientAwareness,
     };
diff --git a/src/core/__tests__/QueryManager/index.ts b/src/core/__tests__/QueryManager/index.ts
index be28a6b575e..4435bf5515d 100644
--- a/src/core/__tests__/QueryManager/index.ts
+++ b/src/core/__tests__/QueryManager/index.ts
@@ -6180,7 +6180,11 @@ describe("QueryManager", () => {
       }).toThrowError(/Cannot set property defaultContext/);
     });
 
-    it("`defaultContext` will be applied to the context of a query", async () => {
+    it.each([
+      ["query", {method: "query", option: "query"}],
+      ["mutation", {method:"mutate", option: "mutation"}],
+      ["subscription", {method:"subscribe", option: "query"}]
+    ]as const)("`defaultContext` will be applied to the context of a %s", async (_, {method, option}) => {
       let context: any;
       const client = new ApolloClient({
         cache: new InMemoryCache(),
@@ -6196,8 +6200,9 @@ describe("QueryManager", () => {
         },
       });
 
-      await client.query({
-        query: gql`
+      // @ts-ignore a bit too generic for TS
+      client[method]({
+        [option]: gql`
           query {
             foo
           }