React特征学习Form数据管理示例详解

目录

• Form数据管理
• 重置Form状态
• form验证
• 小结

Form数据管理

有时会遇到多个位置需要用户输入的情况，若每个状态都配置state或handler会很繁琐，可以尝试下面的方法

import * as React from 'react';
const LoginForm = () => {
  // 将多个状态合并为对象
  const [state, setState] = React.useState({
    email: '',
    password: '',
  });
  // 通过单个handler统一管理
  const handleChange = (e) => {
    setState({
      ...state,
      [e.target.id]: e.target.value,
    });
  };
  const handleSubmit = (e) => {
    e.preventDefault();
    alert(state.email + ' ' + state.password);
  };
  return (
    <form onSubmit={handleSubmit}>
      <div>
        <label htmlFor="email">Email</label>
        <input
          id="email"
          type="text"
          value={state.email}
          onChange={handleChange}
        />
      </div>
      <div>
        <label htmlFor="password">Password</label>
        <input
          id="password"
          type="password"
          value={state.password}
          onChange={handleChange}
        />
      </div>
      <button type="submit">Submit</button>
    </form>
  );
};
export { LoginForm };

重置Form状态

由于每次用户输入后都需要数据重置回初始状态，可以使用以下方法来预设初始值，并重置Form内容，方便新用户的再次输入

import * as React from 'react';
const LoginForm = () => {
  // 初始
  const [state, setState] = React.useState({
    // 设置初始值
    email: '123@456.com',
    password: '12345',
  });
  const handleChange = (e) => {
    setState({
      ...state,
      [e.target.id]: e.target.value,
    });
  };
  const handleSubmit = (e) => {
    e.preventDefault();
    // 在这里重置状态
    setState({
      email: '',
      password: '',
    });
    alert(state.email + ' ' + state.password);
  };
  return (
    <form onSubmit={handleSubmit}>
      <div>
        <label htmlFor="email">Email</label>
        <input
          id="email"
          type="text"
          value={state.email}
          onChange={handleChange}
        />
      </div>
      <div>
        <label htmlFor="password">Password</label>
        <input
          id="password"
          type="password"
          value={state.password}
          onChange={handleChange}
        />
      </div>
      <button type="submit">Submit</button>
    </form>
  );
};
export { LoginForm };

屏幕显示如下，submit后 Form内容会被重置

也可以考虑设置一个变量来统一管理初始值，方便对状态的查找和维护

import * as React from 'react';
const LoginForm = () => {
  // 定义初始值
  const INITIAL_STATE = {
    email: '',
    password: '',
  };
  const [state, setState] = React.useState(INITIAL_STATE);
  const handleChange = (e) => {
    setState({
      ...state,
      [e.target.id]: e.target.value,
    });
  };
  const handleSubmit = (e) => {
    e.preventDefault();
    // 重置初始值
    setState(INITIAL_STATE);
  };
  return (
    <form onSubmit={handleSubmit}>
      <div>
        <label htmlFor="email">Email</label>
        <input
          id="email"
          type="text"
          value={state.email}
          onChange={handleChange}
        />
      </div>
      <div>
        <label htmlFor="password">Password</label>
        <input
          id="password"
          type="password"
          value={state.password}
          onChange={handleChange}
        />
      </div>
      <button type="submit">Submit</button>
    </form>
  );
};
export { LoginForm };

form验证

验证Form的输入是不可或缺的流程，可参考以下方案

import * as React from 'react';
const LoginForm = () => {
  const INITIAL_STATE = {
    email: '',
    password: '',
  };
  // 设置Validation要求
  const VALIDATION = {
    email: [
      {
        isValid: (value) => !!value,
        message: 'Is required.',
      },
      {
        isValid: (value) => /\S+@\S+\.\S+/.test(value),
        message: 'Needs to be an email.',
      },
    ],
    password: [
      {
        isValid: (value) => !!value,
        message: 'Is required.',
      },
    ],
  };
  // 获取ErrorsFields
  const getErrorState = (state) =>
    Object.keys(state).reduce((acc, key) => {
      if (!VALIDATION[key]) return acc;
      const errorsPerField = VALIDATION[key].map((validation) => ({
          isValid: validation.isValid(state[key]),
          message: validation.message,
        })).filter((errorPerField) => !errorPerField.isValid);
      return { ...acc, [key]: errorsPerField };
    }, {});
  const [state, setState] = React.useState(INITIAL_STATE);
  // 设置错误信息变量
  const errorState = getErrorState(state);
  console.log(errorState);
  const handleChange = (e) => {
    setState({
      ...state,
      [e.target.id]: e.target.value,
    });
  };
  const handleSubmit = (e) => {
    e.preventDefault();
    // 获取错误反馈
    const hasErrors = Object.values(errorFields).flat().length > 0;
    if (hasErrors) return;
    setState(INITIAL_STATE);
  };
  return (
    <form onSubmit={handleSubmit}>
      <div>
        <label htmlFor="email">Email</label>
        <input
          id="email"
          type="text"
          value={state.email}
          onChange={handleChange}
        />
         {/* 显示email错误 */}
        {errorState.email?.length ? (
          <span style={{ color: 'red' }}>
            {errorState.email[0].message}
          </span>
        ) : null}
      </div>
      <div>
        <label htmlFor="password">Password</label>
        <input
          id="password"
          type="password"
          value={state.password}
          onChange={handleChange}
        />
        {/* 显示password错误 */}
        {errorState.password?.length ? (
          <span style={{ color: 'red' }}>
            {errorState.password[0].message}
          </span>
        ) : null}
      </div>
      <button type="submit">Submit</button>
    </form>
  );
};
export { LoginForm };

效果显示如下

小结

到这里完成一个简易的React Login Form， 然而现实中React Form的问题还有很多， 随着学习的深入，会继续探索Form实用的复杂性，更多关于React特征Form数据管理的资料请关注其它相关文章！