Basic error validation in the form

app/api/authentication.tsx

@@ -1,7 +1,7 @@
 /* Copyright (C) 2024 Manuel Bustillo*/
 
-import { getCsrfToken, getSlug } from '@/app/lib/utils';
+import { asArray, getCsrfToken, getSlug } from '@/app/lib/utils';
-import { Captcha, User } from '@/app/lib/definitions';
+import { Captcha, StructuredErrors, User } from '@/app/lib/definitions';
 
 export function login({ email, password, onLogin }: { email: string, password: string, onLogin: (user: User) => void }) {
   return fetch(`/api/${getSlug()}/users/sign_in`, {
@@ -34,13 +34,23 @@ export function logout({ onLogout }: { onLogout: () => void }) {
     .catch((error) => console.error(error));
 }
 
-export function register({slug, email, password, passwordConfirmation, captcha, onRegister}: {
+function flattenErrors(errors: StructuredErrors): string[] {
+  if(errors instanceof Array) {
+    return errors;
+  }
+  return Object.keys(errors).map((key) => {
+    return `${key}: ${asArray(errors[key]).join(', ')}`;
+  });
+}
+
+export function register({slug, email, password, passwordConfirmation, captcha, onRegister, onError}: {
   slug: string,
   email: string,
   password: string,
   passwordConfirmation: string,
   captcha: Captcha,
-  onRegister: () => void
+  onRegister: () => void,
+  onError: (errors: string[]) => void
 }){
   fetch(`/api/${slug}/users`, {
     method: 'POST',
@@ -55,6 +65,13 @@ export function register({slug, email, password, passwordConfirmation, captcha,
       'Content-Type': 'application/json',
       'X-CSRF-TOKEN': getCsrfToken(),
     }
-  }).then(onRegister)
+  }).then((response) => {
-    .catch((error) => console.error(error));
+    if(response.ok) {
+      response.json().then(onRegister);
+    } else {
+      response.json().then((data: any) => {
+        onError(data.errors && flattenErrors(data.errors) || [data.error]);
+      });
+    }
+  })
 }

app/lib/definitions.ts

@@ -69,4 +69,8 @@ export type User = {
 export type Captcha = {
   id: string;
   answer: string;
-}
+}
+
+export type StructuredErrors = {
+  [key: string]: string[]|string;
+};

app/lib/utils.ts

@@ -13,3 +13,8 @@ export const getSlug = () => localStorage.getItem('slug') || 'default';
 export const capitalize = (val:string) => {
   return String(val).charAt(0).toUpperCase() + String(val).slice(1);
 }
+
+// From https://stackoverflow.com/a/62118163/3607039
+export function asArray<T>(value: T | T[]): T[] {
+  return ([] as T[]).concat(value)
+}

app/ui/components/registration-form.tsx

@@ -11,6 +11,8 @@ import { register } from '@/app/api/authentication';
 import { getCaptchaChallenge } from '@/app/api/captcha';
 
 export default function RegistrationForm() {
+  const [errors, setErrors] = useState<string[]>([]);
+
   const [email, setEmail] = useState<string>("");
   const [password, setPassword] = useState<string>("");
   const [passwordConfirmation, setPasswordConfirmation] = useState<string>("");
@@ -26,6 +28,7 @@ export default function RegistrationForm() {
         console.log(id, url);
         setCaptchaId(id);
         setCaptchaUrl(url);
+        setCaptchaAnswer("");
       }
     });
   }
@@ -52,10 +55,14 @@ export default function RegistrationForm() {
       </FloatLabel>
       <img className="w-96" src={captchaUrl} alt="captcha" />
       <FloatLabel className="my-4">
-        <InputText id="captcha" type="text" className='rounded-sm' onChange={(e) => setCaptchaAnswer(e.target.value)} />
+        <InputText id="captcha" type="text" className='rounded-sm' value={captchaAnswer} onChange={(e) => setCaptchaAnswer(e.target.value)} />
         <label htmlFor="captcha">Captcha</label>
       </FloatLabel>
 
+      {errors.map((error, index) => (
+        <div key={index} className="text-red-500">{error}</div>
+      ))}
+
 
       <button
         className={classNames('primary')}
@@ -70,7 +77,8 @@ export default function RegistrationForm() {
               id: captchaId,
               answer: captchaAnswer
             },
-            onRegister: () => { console.log("registered") }
+            onRegister: () => { setErrors([]) },
+            onError: (errors) => { refreshCaptcha(); setErrors(errors)  }
           }
         )}
       >