feat: add form_post response mode support for Apple OAuth

Author: omnimaxxing

package.json

@@ -4,7 +4,7 @@
   "type": "module",
   "homepage:": "https://payloadcms.com",
   "repository": "https://github.com/WilsonLe/payload-oauth2",
-  "description": "OAuth2 plugin for Payload CMS",
+  "description": "OAuth2 plugin for Payload CMS with Apple Sign In support",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
   "keywords": [
@@ -14,7 +14,8 @@
     "typescript",
     "react",
     "oauth2",
-    "payload-plugin"
+    "payload-plugin",
+    "apple-sign-in"
   ],
   "files": [
     "dist"

src/callback-endpoint.ts

@@ -15,19 +15,23 @@ export const createCallbackEndpoint = (
  // Support both GET (default OAuth2) and POST (required for Apple OAuth with form_post)
 	// - GET: Used by most OAuth providers (Google, GitHub, etc.)
 	// - POST: Required by Apple when requesting name/email scopes with response_mode=form_post
-	method: ['get', 'post'],
+	method: 'post' as const,
 	path: pluginOptions.callbackPath || '/oauth/callback',
   handler: async (req) => {
     try {
-   // Handle authorization code from both GET query params and POST body
-			// This enables support for Apple's form_post response mode while maintaining
-			// compatibility with traditional OAuth2 GET responses
-			const code = req.method === 'POST' ? req.body?.code : req.query?.code
+      // Handle authorization code from both GET query params and POST body
+      // This enables support for Apple's form_post response mode while maintaining
+      // compatibility with traditional OAuth2 GET responses
+      const code = req.method === "POST"
+        ? (req.body)?.code  // Type assertion for body
+				: (req.query)?.code  // Type assertion for query
       	// Improved error handling to clearly indicate whether we're missing the code
 			// from POST body (Apple OAuth) or GET query parameters (standard OAuth)
     	if (typeof code !== 'string')
 				throw new Error(
-						`Code not found in ${req.method === 'POST' ? 'body' : 'query'}: ${JSON.stringify(req.method === 'POST' ? req.body : req.query)}`,
+          `Code not found in ${req.method === 'POST' ? 'body' : 'query'}: ${JSON.stringify(
+						req.method === 'POST' ? req.body : req.query
+					)}`,
 				)
 
       // /////////////////////////////////////