react-select简介
React-Select是github上一个极其火的控件库，星数达到13004，它是React开发中几乎是你必需打交道的一个内容。React Select的基本功能实现的是一个表单中的常见的下拉列表框控件，其实它的功能扩展来看远远不止如此，它支持：
-
多选
-
样式定制
-
多级联动选择
-
异步加载
等等。
但是，如果在你的开发中使用的是一个很基础性的下拉列表框，那么你可以直接使用类似于Semantic UI或者是Material React控件库的Select组件，甚至是最基本的HTML5组件中的那个。
值得注意的是，如如今react-select组件从1.0升级到2.0，变化了巨大变化。有关细节请参考官方网站，总起来看越升级越容易使用，功能也越强大。
在Formik中使用react-select组件
Formik官方也提供了一个使用react-select组件的基本例子，但是使用的是react-select组件的Ver 1.x。在1.x版本时期，组件的样式是使用css方案定义的，但是升级到2.0后，样式使用了更为先进且更迎合React开发思想的Emotion这个开源库（使用JSX组件思想——css-in-JS——开发样式）。由于Formik官方提供的相关实例极为简单，所以几需要作两处修改即可。
工程名称：formik-09x-react-select-example，主要文件：index.js
修改后完整代码如下：
import './formik-demo.css';
import React from 'react';
import { render } from 'react-dom';
import { withFormik } from 'formik';
//ERROR NOW: import Yup from 'yup';==>changed into the following
import * as Yup from 'yup';
import Select from 'react-select';
//NOT SUPPORTED IN VERSION 2.X.
// Styles are now implemented with css-in-js rather than less / scss stylesheets
//import 'react-select/dist/react-select.css';
// Helper styles for demo
import './formik-demo.css';
import {
MoreResources,DisplayFormikState,} from './formik-helper';
import SimpleSelect from './SimpleSelect'
import AnimatedMulti from './AnimationMultiSelect'
const formikEnhancer = withFormik({
mapPropsToValues: props => ({
email: '',topics: []
}),validationSchema: Yup.object().shape({
email: Yup.string()
.email('Invalid email address')
.required('Email is required!'),topics: Yup.array()
.min(3,'Pick at least 3 tags')
.of(
Yup.object().shape({
label: Yup.string().required(),value: Yup.string().required(),})
),}),handleSubmit: (values,{ setSubmitting }) => {
const payload = {
...values,topics: values.topics.map(t => t.value),};
setTimeout(() => {
alert(JSON.stringify(payload,null,2));
setSubmitting(false);
},1000);
},displayName: 'MyForm'
});
const MyForm = props => {
const {
values,touched,dirty,errors,handleChange,handleBlur,handleSubmit,handleReset,setFieldValue,setFieldTouched,isSubmitting,} = props;
return (
<form onSubmit={handleSubmit}>
<label htmlFor="email" style={{ display: 'block' }}>
Email
</label>
<input
id="email"
placeholder="Enter your email"
type="email"
value={values.email}
onChange={handleChange}
onBlur={handleBlur}
/>
{errors.email &&
touched.email && (
<div style={{ color: 'red',marginTop: '.5rem' }}>
{errors.email}
</div>
)}
<MySelect
value={values.topics}
onChange={setFieldValue}
onBlur={setFieldTouched}
error={errors.topics}
touched={touched.topics}
/>
<button
type="button"
className="outline"
onClick={handleReset}
disabled={!dirty || isSubmitting}
>
Reset
</button>
<button type="submit" disabled={isSubmitting}>
Submit
</button>
<DisplayFormikState {...props} />
</form>
);
};
const options = [
{ value: 'Food',label: 'Food' },{ value: 'Being Fabulous',label: 'Being Fabulous' },{ value: 'Ken Wheeler',label: 'Ken Wheeler' },{ value: 'ReasonML',label: 'ReasonML' },{ value: 'Unicorns',label: 'Unicorns' },{ value: 'Kittens',label: 'Kittens' },];
class MySelect extends React.Component {
handleChange = value => {
// this is going to call setFieldValue and manually update values.topcis
this.props.onChange('topics',value);
};
handleBlur = () => {
// this is going to call setFieldTouched and manually update touched.topcis
this.props.onBlur('topics',true);
};
render() {
return (
<div style={{ margin: '1rem 0' }}>
<label htmlFor="color">
Topics (select at least 3){' '}
</label>
<Select
id="color"
options={options}
isMulti
onChange={this.handleChange}
onBlur={this.handleBlur}
value={this.props.value}
/>
{!!this.props.error &&
this.props.touched && (
<div style={{ color: 'red',marginTop: '.5rem' }}>
{this.props.error}
</div>
)}
</div>
);
}
}
const MyEnhancedForm = formikEnhancer(MyForm);
const App = () => (
<div className="app">
<h1>
Using{' '}
<a href="https://github.com/jaredpalmer/formik">
Formik
</a>{' '}
with 3rd-party input components
</h1>
<p>
This example shows to use Formik with a 3rd-party
input component. The trick is to use Formik's{' '}
<code>setFieldValue</code> prop and a custom component
class whenever you need a custom change handler.{' '}
</p>
<p>
To show this off,below is a Formik-enhanced form. It
has a "vanilla" Formik input for <code>email</code>{' '}
and a custom select component for <code>topics</code>{' '}
that uses Jed Watson's {' '}
<a href="https://github.com/JedWatson/react-select">
react-select
</a>{' '}
library.
</p>
<MyEnhancedForm />
<hr/>
<SimpleSelect/>
<hr/>
<AnimatedMulti/>
<hr/>
<MoreResources />
</div>
);
render(<App />,document.getElementById('root'));
第一处修改是屏蔽css文件的导入引用，如下：
//import 'react-select/dist/react-select.css';
第二处更为简单，只需要把<Select/>组件中的属性表达方式修改一下，即把multi={true}修改为isMulti就可以了，如下：
<Select
id="color"
options={options}
isMulti
onChange={this.handleChange}
onBlur={this.handleBlur}
value={this.props.value}
/>
另外还添加了两个我自己加入的react-select组件，分别是SimpleSelect和AnimationMultiSelect，它们各自的源码如下，请参考：
//SimpleSelect.js
import React,{Component} from 'react'
import Select from 'react-select'
const options=[
{value:'liu',label:'刘备'},{value:'guan',label:'关羽'},{value:'zhang',label:'张飞'}
]
const SimpleSelect=()=>(
<Select options={options}/>
)
export default SimpleSelect
//AnimationMultiSelect
import React from 'react';
import Select from 'react-select';
import makeAnimated from 'react-select/lib/animated';
// import { colourOptions } from '../data';
const colourOptions=[
{value:'c1',{value:'c2',label:'关羽1'},{value:'c3',label:'关羽2'},{value:'c4',label:'关羽3'},{value:'c5',label:'张飞'}
]
export default function AnimatedMulti() {
return (
<Select
closeMenuOnSelect={false}
components={makeAnimated()}
defaultValue={[colourOptions[4],colourOptions[5]]}
isMulti
options={colourOptions}
/>
);
}
引用
1，https://react-select.com/home#getting-started
2，https://blog.csdn.net/Tony1590112/article/details/78296345
3，https://github.com/emotion-js/emotion
4，https://github.com/jaredpalmer/formik
