ReactJs自定义表单验证不起作用-Next.Js

Question

我正在尝试验证一个表单。当刷新页面并单击提交按钮时，只会生成最后一个元素的错误，根据验证，它应该会为每个输入生成错误
表单问题的屏幕截图
表单验证与onChange事件完美配合。但当刷新页面时，它并不能正常工作，并且我点击提交按钮而不将值输入

当我点击"；提交"；按钮，它生成一个对象{message: 'Required'}，在这个对象中，只生成消息键。它应该生成具有所有输入名称的对象，如{name: 'Required', email: 'Required', message: 'Required'}。

这是我的代码：

import { useState } from "react";
function ContactForm() {
const [fields, setFields] = useState({});
const [errors, setErrors] = useState({});
const [formValid, setFormValid] = useState(false);
async function handleOnSubmit(e) {
e.preventDefault();
console.log('fields', fields);
console.log('errors', errors);
console.log('formValid', formValid);
const formData = {};
[...e.currentTarget.elements].map((field) => {
if (!field.name) return false;
checkValidation([field.name], field.value);
setFields({...fields, [field.name]: field.value});
});
if (formValid === false) return false;
try {
const response = await fetch('/api/mail', {
method: 'post',
body: JSON.stringify(formData)
});
const body = await response.json();
console.log(body);
} catch (error) {
console.log(error);
}
console.log(formData);
}
function handleValidation(e) {
const name = e.target.name;
const value = e.target.value;
checkValidation(name, value);
}
function checkValidation(name, value) {
if (value === "") {
delete fields[name];
setErrors({...errors, [name]: 'Required'});
setFormValid(false);
return false;
}
delete errors[name];
setFields({...fields, [name]: value});
setFormValid(true);
// Special validation for email
emailValidation(name, value);
console.log('fields on validaton', fields);
console.log('errors on validation', errors);
}
// Email Validation
function emailValidation(name, value) {
const emailRegex = new RegExp(/[a-z0-9._%+-]+@[a-z0-9.-]+.[a-z]{2,15}/g);
if ((name == 'email') && (emailRegex.test(value) === false)) {
delete fields[name];
setErrors({...errors, [name]: 'Email is not validate'});
setFormValid(false);
}
}
return (
<div className="mt-5 mt-md-0">
<h1 className="section-title h1-responsive text-center mb-4">
<span>
Contact Us
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 456.99 38"><defs><style dangerouslySetInnerHTML={{__html: ".cls-1{fill:#cb0a34;}" }} /></defs><title>latest from out videos</title><g id="Layer_2" data-name="Layer 2"><g id="Layer_1-2" data-name="Layer 1"><path className="cls-1" d="M456.28,8.29a4.6,4.6,0,0,0,.29-.59c0-.11.08-.21.11-.31a4.56,4.56,0,0,0,.21-.72l0-.21A6.11,6.11,0,0,0,457,5.6h0a5.5,5.5,0,1,0-9.24,4C422.6,9.89,288,9.52,281.13,9.52h-31c-7.86,0-15.13,2.18-21.14,7.26a30.14,30.14,0,0,0-8.72-5.25c-4.68-1.82-9.42-2-14.32-2H9.24A5.5,5.5,0,1,0,0,5.5v0c0,.05,0,.09,0,.14a3.4,3.4,0,0,0,0,.45c0,.12,0,.23,0,.35l.06.3A1.82,1.82,0,0,0,.22,7,5.48,5.48,0,0,0,4.5,10.9a5.13,5.13,0,0,0,1.12.16c.85,0,1.7,0,2.54,0H209.44a28.85,28.85,0,0,1,19,7.26,28.31,28.31,0,0,0-6.38,9.13L229,38.29,236,27.45h0a28.11,28.11,0,0,0-6.38-9.12A28.8,28.8,0,0,1,241.09,12c4-1.09,8-1,12.14-1H451l.54,0a5.47,5.47,0,0,0,3.21-1l.07,0s0,0,.05-.05a4.53,4.53,0,0,0,.62-.54l.24-.26a6.41,6.41,0,0,0,.39-.52C456.15,8.52,456.21,8.4,456.28,8.29Z" /></g></g></svg>
</span>
</h1>
<form className="contact_form" method="post" onSubmit={handleOnSubmit}>
<div className="response-status"></div>
<div className="form-group row">
<div className="col-md-6 mb-2">
<label className="mb-1">Name <span className="text-danger">*</span></label>
<input
type="text"
name="name"
className={`form-control ${errors.name ? 'is-invalid' : ''}`}
onChange={handleValidation}
/>
{errors.name && <span className="text-danger">{errors.name}</span>}
</div>
<div className="col-md-6 mb-2">
<label className="mb-1">Email <span className="text-danger">*</span></label>
<input
type="text"
name="email"
className={`form-control ${errors.email ? 'is-invalid' : ''}`}
onChange={handleValidation}
/>
{errors.email && <span className="text-danger">{errors.email}</span>}
</div>
<div className="col-md-12 mb-2">
<label className="mb-1">Subject:</label>
<input type="text" name="subject" className="form-control" />
</div>
<div className="col-md-12 mb-3">
<label className="mb-1">Message <span className="text-danger">*</span></label>
<textarea
name="message"
className={`form-control ${errors.message ? 'is-invalid' : ''}`}
rows="5"
onChange={handleValidation}
></textarea>
{errors.message && <span className="text-danger">{errors.message}</span>}
</div>
<div className="col-md-12">
<button type="submit" className="btn btn-primary btn-block rounded waves-effect waves-light">Send Message</button>
</div>
</div>
</form>
</div>
)
}
export default ContactForm

我不知道为什么它不能正常工作。请检查代码。我在代码中找不到问题，我被卡住了。

Answer 1

您正在从许多地方设置状态，并且也在循环中设置状态。在某个时刻，该值可能已经过时或不可靠。

如果要根据以前的值更新状态的值，建议使用以下模式：setState(prevState => prevState*2)

基本上使用上一个状态的值来使用这个回调模式获得新状态。

import { useState } from "react";
import "./styles.css";
export default function App() {
const [fields, setFields] = useState({});
const [errors, setErrors] = useState({});
const [formValid, setFormValid] = useState(false);
async function handleOnSubmit(e) {
e.preventDefault();
console.log("fields", fields);
console.log("errors", errors);
console.log("formValid", formValid);
const formData = {};
[...e.currentTarget.elements].map((field) => {
if (!field.name) return false;
checkValidation([field.name], field.value);
setFields({ ...fields, [field.name]: field.value });
});
if (formValid === false) return false;
try {
const response = await fetch("/api/mail", {
method: "post",
body: JSON.stringify(formData)
});
const body = await response.json();
console.log(body);
} catch (error) {
console.log(error);
}
console.log(formData);
}
function handleValidation(e) {
const name = e.target.name;
const value = e.target.value;
checkValidation(name, value);
}
function checkValidation(name, value) {
if (value === "") {
delete fields[name];
setErrors((errors) => {
return { ...errors, [name]: "Required" };
});
setFormValid(false);
return false;
}
delete errors[name];
setFields({ ...fields, [name]: value });
setFormValid(true);
// Special validation for email
emailValidation(name, value);
console.log("fields on validaton", fields);
console.log("errors on validation", errors);
}
// Email Validation
function emailValidation(name, value) {
const emailRegex = new RegExp(/[a-z0-9._%+-]+@[a-z0-9.-]+.[a-z]{2,15}/g);
if (name == "email" && emailRegex.test(value) === false) {
delete fields[name];
setErrors((errors) => ({ ...errors, [name]: "Email is not validate" }));
setFormValid(false);
}
}
return (
<div className="mt-5 mt-md-0">
<h1 className="section-title h1-responsive text-center mb-4">
<span>
Contact Us
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 456.99 38">
<defs>
<style
dangerouslySetInnerHTML={{ __html: ".cls-1{fill:#cb0a34;}" }}
/>
</defs>
<title>latest from out videos</title>
<g id="Layer_2" data-name="Layer 2">
<g id="Layer_1-2" data-name="Layer 1">
<path
className="cls-1"
d="M456.28,8.29a4.6,4.6,0,0,0,.29-.59c0-.11.08-.21.11-.31a4.56,4.56,0,0,0,.21-.72l0-.21A6.11,6.11,0,0,0,457,5.6h0a5.5,5.5,0,1,0-9.24,4C422.6,9.89,288,9.52,281.13,9.52h-31c-7.86,0-15.13,2.18-21.14,7.26a30.14,30.14,0,0,0-8.72-5.25c-4.68-1.82-9.42-2-14.32-2H9.24A5.5,5.5,0,1,0,0,5.5v0c0,.05,0,.09,0,.14a3.4,3.4,0,0,0,0,.45c0,.12,0,.23,0,.35l.06.3A1.82,1.82,0,0,0,.22,7,5.48,5.48,0,0,0,4.5,10.9a5.13,5.13,0,0,0,1.12.16c.85,0,1.7,0,2.54,0H209.44a28.85,28.85,0,0,1,19,7.26,28.31,28.31,0,0,0-6.38,9.13L229,38.29,236,27.45h0a28.11,28.11,0,0,0-6.38-9.12A28.8,28.8,0,0,1,241.09,12c4-1.09,8-1,12.14-1H451l.54,0a5.47,5.47,0,0,0,3.21-1l.07,0s0,0,.05-.05a4.53,4.53,0,0,0,.62-.54l.24-.26a6.41,6.41,0,0,0,.39-.52C456.15,8.52,456.21,8.4,456.28,8.29Z"
/>
</g>
</g>
</svg>
</span>
</h1>
<form className="contact_form" method="post" onSubmit={handleOnSubmit}>
<div className="response-status"></div>
<div className="form-group row">
<div className="col-md-6 mb-2">
<label className="mb-1">
Name <span className="text-danger">*</span>
</label>
<input
type="text"
name="name"
className={`form-control ${errors.name ? "is-invalid" : ""}`}
onChange={handleValidation}
/>
{errors.name && <span className="text-danger">{errors.name}</span>}
</div>
<div className="col-md-6 mb-2">
<label className="mb-1">
Email <span className="text-danger">*</span>
</label>
<input
type="text"
name="email"
className={`form-control ${errors.email ? "is-invalid" : ""}`}
onChange={handleValidation}
/>
{errors.email && (
<span className="text-danger">{errors.email}</span>
)}
</div>
<div className="col-md-12 mb-2">
<label className="mb-1">Subject:</label>
<input type="text" name="subject" className="form-control" />
</div>
<div className="col-md-12 mb-3">
<label className="mb-1">
Message <span className="text-danger">*</span>
</label>
<textarea
name="message"
className={`form-control ${errors.message ? "is-invalid" : ""}`}
rows="5"
onChange={handleValidation}
></textarea>
{errors.message && (
<span className="text-danger">{errors.message}</span>
)}
</div>
<div className="col-md-12">
<button
type="submit"
className="btn btn-primary btn-block rounded waves-effect waves-light"
>
Send Message
</button>
</div>
</div>
</form>
</div>
);
}

沙盒