feat: add redirectToSignUp() to ClerkMiddlewareAuthObject

Author: sambarnes

packages/nextjs/src/app-router/server/auth.ts

@@ -25,6 +25,16 @@ type Auth = AuthObject & {
    * `auth()` on the server-side can only access redirect URLs defined via [environment variables](https://clerk.com/docs/deployments/clerk-environment-variables#sign-in-and-sign-up-redirects) or [`clerkMiddleware` dynamic keys](https://clerk.com/docs/references/nextjs/clerk-middleware#dynamic-keys).
    */
   redirectToSignIn: RedirectFun<ReturnType<typeof redirect>>;
+
+  /**
+   * The `auth()` helper returns the `redirectToSignUp()` method, which you can use to redirect the user to the sign-up page.
+   *
+   * @param [returnBackUrl] {string | URL} - The URL to redirect the user back to after they sign up.
+   *
+   * @note
+   * `auth()` on the server-side can only access redirect URLs defined via [environment variables](https://clerk.com/docs/deployments/clerk-environment-variables#sign-in-and-sign-up-redirects) or [`clerkMiddleware` dynamic keys](https://clerk.com/docs/references/nextjs/clerk-middleware#dynamic-keys).
+   */
+  redirectToSignUp: RedirectFun<ReturnType<typeof redirect>>;
 };
 
 export interface AuthFn {
@@ -104,7 +114,28 @@ export const auth: AuthFn = async () => {
     });
   };
 
-  return Object.assign(authObject, { redirectToSignIn });
+  const redirectToSignUp: RedirectFun<never> = (opts = {}) => {
+    const clerkRequest = createClerkRequest(request);
+    const devBrowserToken =
+      clerkRequest.clerkUrl.searchParams.get(constants.QueryParameters.DevBrowser) ||
+      clerkRequest.cookies.get(constants.Cookies.DevBrowser);
+
+    const encryptedRequestData = getHeader(request, constants.Headers.ClerkRequestData);
+    const decryptedRequestData = decryptClerkRequestData(encryptedRequestData);
+
+    return createRedirect({
+      redirectAdapter: redirect,
+      devBrowserToken: devBrowserToken,
+      baseUrl: clerkRequest.clerkUrl.toString(),
+      publishableKey: decryptedRequestData.publishableKey || PUBLISHABLE_KEY,
+      signInUrl: decryptedRequestData.signInUrl || SIGN_IN_URL,
+      signUpUrl: decryptedRequestData.signUpUrl || SIGN_UP_URL,
+    }).redirectToSignUp({
+      returnBackUrl: opts.returnBackUrl === null ? '' : opts.returnBackUrl || clerkUrl?.toString(),
+    });
+  };
+
+  return Object.assign(authObject, { redirectToSignIn, redirectToSignUp });
 };
 
 auth.protect = async (...args: any[]) => {

packages/nextjs/src/server/clerkMiddleware.ts

@@ -18,8 +18,10 @@ import {
   isNextjsNotFoundError,
   isNextjsRedirectError,
   isRedirectToSignInError,
+  isRedirectToSignUpError,
   nextjsRedirectError,
   redirectToSignInError,
+  redirectToSignUpError,
 } from './nextErrors';
 import type { AuthProtect } from './protect';
 import { createProtect } from './protect';
@@ -34,6 +36,7 @@ import {
 
 export type ClerkMiddlewareAuthObject = AuthObject & {
   redirectToSignIn: RedirectFun<Response>;
+  redirectToSignUp: RedirectFun<Response>;
 };
 
 export interface ClerkMiddlewareAuth {
@@ -172,9 +175,13 @@ export const clerkMiddleware: ClerkMiddleware = (...args: unknown[]) => {
       logger.debug('auth', () => ({ auth: authObject, debug: authObject.debug() }));
 
       const redirectToSignIn = createMiddlewareRedirectToSignIn(clerkRequest);
+      const redirectToSignUp = createMiddlewareRedirectToSignUp(clerkRequest);
       const protect = await createMiddlewareProtect(clerkRequest, authObject, redirectToSignIn);
 
-      const authObjWithMethods: ClerkMiddlewareAuthObject = Object.assign(authObject, { redirectToSignIn });
+      const authObjWithMethods: ClerkMiddlewareAuthObject = Object.assign(authObject, {
+        redirectToSignIn,
+        redirectToSignUp,
+      });
       const authHandler = () => Promise.resolve(authObjWithMethods);
       authHandler.protect = protect;
 
@@ -311,6 +318,15 @@ const createMiddlewareRedirectToSignIn = (
   };
 };
 
+const createMiddlewareRedirectToSignUp = (
+  clerkRequest: ClerkRequest,
+): ClerkMiddlewareAuthObject['redirectToSignUp'] => {
+  return (opts = {}) => {
+    const url = clerkRequest.clerkUrl.toString();
+    redirectToSignUpError(url, opts.returnBackUrl);
+  };
+};
+
 const createMiddlewareProtect = (
   clerkRequest: ClerkRequest,
   authObject: AuthObject,
@@ -363,6 +379,16 @@ const handleControlFlowErrors = (
     }).redirectToSignIn({ returnBackUrl: e.returnBackUrl });
   }
 
+  if (isRedirectToSignUpError(e)) {
+    return createRedirect({
+      redirectAdapter,
+      baseUrl: clerkRequest.clerkUrl,
+      signInUrl: requestState.signInUrl,
+      signUpUrl: requestState.signUpUrl,
+      publishableKey: requestState.publishableKey,
+    }).redirectToSignUp({ returnBackUrl: e.returnBackUrl });
+  }
+
   if (isNextjsRedirectError(e)) {
     return redirectAdapter(e.redirectUrl);
   }

packages/nextjs/src/server/nextErrors.ts

@@ -4,6 +4,7 @@
 const CONTROL_FLOW_ERROR = {
   REDIRECT_TO_URL: 'CLERK_PROTECT_REDIRECT_TO_URL',
   REDIRECT_TO_SIGN_IN: 'CLERK_PROTECT_REDIRECT_TO_SIGN_IN',
+  REDIRECT_TO_SIGN_UP: 'CLERK_PROTECT_REDIRECT_TO_SIGN_UP',
 };
 
 /**
@@ -99,6 +100,13 @@ function redirectToSignInError(url: string, returnBackUrl?: string | URL | null)
   });
 }
 
+function redirectToSignUpError(url: string, returnBackUrl?: string | URL | null): never {
+  nextjsRedirectError(url, {
+    clerk_digest: CONTROL_FLOW_ERROR.REDIRECT_TO_SIGN_UP,
+    returnBackUrl: returnBackUrl === null ? '' : returnBackUrl || url,
+  });
+}
+
 /**
  * Checks an error to determine if it's an error generated by the
  * `redirect(url)` helper.
@@ -135,11 +143,21 @@ function isRedirectToSignInError(error: unknown): error is RedirectError<{ retur
   return false;
 }
 
+function isRedirectToSignUpError(error: unknown): error is RedirectError<{ returnBackUrl: string | URL }> {
+  if (isNextjsRedirectError(error) && 'clerk_digest' in error) {
+    return error.clerk_digest === CONTROL_FLOW_ERROR.REDIRECT_TO_SIGN_UP;
+  }
+
+  return false;
+}
+
 export {
   isNextjsNotFoundError,
   isLegacyNextjsNotFoundError,
   redirectToSignInError,
+  redirectToSignUpError,
   nextjsRedirectError,
   isNextjsRedirectError,
   isRedirectToSignInError,
+  isRedirectToSignUpError,
 };