feat!: convert HTTP errors to ServerError for Apollo Client

.changeset/http-error-server-error.md

@@ -0,0 +1,48 @@
+---
+'apollo-angular': major
+---
+
+**BREAKING CHANGE**: HTTP errors now return Apollo Client's `ServerError` instead of Angular's `HttpErrorResponse`
+
+When Apollo Server returns non-2xx HTTP status codes (status >= 300), apollo-angular's HTTP links now return `ServerError` from `@apollo/client/errors` instead of Angular's `HttpErrorResponse`. This enables proper error detection in errorLinks using `ServerError.is(error)` and provides consistent error handling with Apollo Client's ecosystem.
+
+**Migration Guide:**
+
+Before:
+```typescript
+import { HttpErrorResponse } from '@angular/common/http';
+
+link.request(operation).subscribe({
+  error: (err) => {
+    if (err instanceof HttpErrorResponse) {
+      console.log(err.status);
+      console.log(err.error);
+    }
+  }
+});
+```
+
+After:
+```typescript
+import { ServerError } from '@apollo/client/errors';
+
+link.request(operation).subscribe({
+  error: (err) => {
+    if (ServerError.is(err)) {
+      console.log(err.statusCode);
+      console.log(err.bodyText);
+      console.log(err.response.headers);
+    }
+  }
+});
+```
+
+**Properties Changed:**
+- `err.status` → `err.statusCode`
+- `err.error` → `err.bodyText` (always string, JSON stringified for objects)
+- `err.headers` (Angular HttpHeaders) → `err.response.headers` (native Headers)
+- Access response via `err.response` which includes: `status`, `statusText`, `ok`, `url`, `type`, `redirected`
+
+**Note:** This only affects HTTP-level errors (status >= 300). Network errors and other error types remain unchanged. GraphQL errors in the response body are still processed normally through Apollo Client's error handling.
+
+Fixes #2394

packages/apollo-angular/http/src/http-batch-link.ts

@@ -1,9 +1,10 @@
 import { print } from 'graphql';
 import { Observable } from 'rxjs';
-import { HttpClient, HttpContext, HttpHeaders } from '@angular/common/http';
+import { HttpClient, HttpContext, HttpHeaders, HttpErrorResponse } from '@angular/common/http';
 import { Injectable } from '@angular/core';
 import { ApolloLink } from '@apollo/client';
 import { BatchLink } from '@apollo/client/link/batch';
+import { ServerError } from '@apollo/client/errors';
 import type { HttpLink } from './http-link';
 import { Body, Context, OperationPrinter, Request } from './types';
 import {
@@ -14,6 +15,43 @@ import {
   prioritize,
 } from './utils';
 
+function convertHttpErrorToApolloError(err: HttpErrorResponse): Error {
+  // Create a Response-like object that satisfies Apollo Client's expectations
+  const mockResponse = {
+    status: err.status,
+    statusText: err.statusText,
+    ok: err.ok,
+    url: err.url || '',
+    headers: new Headers(),
+    type: 'error' as ResponseType,
+    redirected: false,
+  } as Response;
+
+  // Convert Angular's HttpHeaders to native Headers
+  err.headers.keys().forEach(key => {
+    const values = err.headers.getAll(key);
+    if (values) {
+      values.forEach(value => mockResponse.headers.append(key, value));
+    }
+  });
+
+  // Get the body text
+  const bodyText = typeof err.error === 'string'
+    ? err.error
+    : JSON.stringify(err.error || {});
+
+  // Return ServerError for non-2xx status codes (following Apollo Client's logic)
+  if (err.status >= 300) {
+    return new ServerError(
+      `Response not successful: Received status code ${err.status}`,
+      { response: mockResponse, bodyText }
+    );
+  }
+
+  // For other HttpErrorResponse cases, return a generic error
+  return new Error(err.message);
+}
+
 export declare namespace HttpBatchLink {
   export type Options = {
     batchMax?: number;
@@ -89,7 +127,10 @@ export class HttpBatchLinkHandler extends ApolloLink {
           throw new Error('File upload is not available when combined with Batching');
         }).subscribe({
           next: result => observer.next(result.body),
-          error: err => observer.error(err),
+          error: err => {
+            if (err instanceof HttpErrorResponse) observer.error(convertHttpErrorToApolloError(err));
+            else observer.error(err);
+          },
           complete: () => observer.complete(),
         });
 

packages/apollo-angular/http/src/http-link.ts

@@ -1,8 +1,9 @@
 import { print } from 'graphql';
 import { Observable } from 'rxjs';
-import { HttpClient, HttpContext } from '@angular/common/http';
+import { HttpClient, HttpContext, HttpErrorResponse } from '@angular/common/http';
 import { Injectable } from '@angular/core';
 import { ApolloLink } from '@apollo/client';
+import { ServerError } from '@apollo/client/errors';
 import { pick } from './http-batch-link';
 import {
   Body,
@@ -15,6 +16,43 @@ import {
 } from './types';
 import { createHeadersWithClientAwareness, fetch, mergeHeaders, mergeHttpContext } from './utils';
 
+function convertHttpErrorToApolloError(err: HttpErrorResponse): Error {
+  // Create a Response-like object that satisfies Apollo Client's expectations
+  const mockResponse = {
+    status: err.status,
+    statusText: err.statusText,
+    ok: err.ok,
+    url: err.url || '',
+    headers: new Headers(),
+    type: 'error' as ResponseType,
+    redirected: false,
+  } as Response;
+
+  // Convert Angular's HttpHeaders to native Headers
+  err.headers.keys().forEach(key => {
+    const values = err.headers.getAll(key);
+    if (values) {
+      values.forEach(value => mockResponse.headers.append(key, value));
+    }
+  });
+
+  // Get the body text
+  const bodyText = typeof err.error === 'string'
+    ? err.error
+    : JSON.stringify(err.error || {});
+
+  // Return ServerError for non-2xx status codes (following Apollo Client's logic)
+  if (err.status >= 300) {
+    return new ServerError(
+      `Response not successful: Received status code ${err.status}`,
+      { response: mockResponse, bodyText }
+    );
+  }
+
+  // For other HttpErrorResponse cases, return a generic error
+  return new Error(err.message);
+}
+
 export declare namespace HttpLink {
   export interface Options extends FetchOptions, HttpRequestOptions {
     operationPrinter?: OperationPrinter;
@@ -94,7 +132,10 @@ export class HttpLinkHandler extends ApolloLink {
             operation.setContext({ response });
             observer.next(response.body);
           },
-          error: err => observer.error(err),
+          error: err => {
+            if (err instanceof HttpErrorResponse) observer.error(convertHttpErrorToApolloError(err));
+            else observer.error(err);
+          },
           complete: () => observer.complete(),
         });