useActionState を例で簡単に学習します (Next.js)

"use client";

import { useActionState } from "react";
import { signUp } from "../actions";

export default function SignUp() {
  const [state, action] = useActionState(signUp, {});

  return (
    <form action={action}>
      <div>
        <label htmlFor="username">Username:</label>
        <input
          type="text"
         >



<p>actions.ts:<br>
</p>

<pre class="brush:php;toolbar:false">"use server";

import { z } from "zod";

const SignUpSchema = z.object({
  username: z.string(),
  password: z
    .string()
    .min(8, { message: "Be at least 8 characters long" })
    .regex(/[a-zA-Z]/, { message: "Contain at least one letter." })
    .regex(/[0-9]/, { message: "Contain at least one number." })
    .regex(/[^a-zA-Z0-9]/, {
      message: "Contain at least one special character.",
    })
    .trim(),
});

export type SignUpActionState = {
  username?: string;
  password?: string;
  errors?: {
    username?: string[];
    password?: string[];
  };
};

export async function signUp(
  _prevState: SignUpActionState,
  form: FormData
): Promise<SignUpActionState> {
  const username = form.get("username") as string;
  const password = form.get("password") as string;

  const validatedFields = SignUpSchema.safeParse({
    username,
    password,
  });

  if (!validatedFields.success) {
    return {
      username,
      password,
      errors: validatedFields.error.flatten().fieldErrors,
    };
  }

  // process validated form inputs here

  return { username, password };
}