我需要你的帮助 !
我正在为我的compagny做一个项目,我应该创建一个可以与React重复的选择字段。所以,当我想保存我的选择时,我有一点问题,如果我刷新页面,默认选项仍然相同(而不是选定的选项)。有我的select.js代码:
import React, { Component, PropTypes } from 'react';
class Select extends React.Component {
constructor(props) {
super(props);
this.state = {value: ''};
this.handleChange = this.handleChange.bind(this);
}
handleChange(data) {
this.setState({value:data.value});
}
render() {
return (
<label>
<select className="widefat" name={this.props.name} onChange={this.handleChange}>
<option value="grapefruit">Grapefruit</option>
<option value="lime">Lime</option>
<option value="coconut">Coconut</option>
<option value="mango">Mango</option>
</select>
</label>
);
}
}
export default Select;
我改变了默认值:
When i change the select option
我认为这是因为在select.js中它将值初始化为''并且不保存选择但我不知道如何保存选择。
这是实现此目的的一种方法:
import React, { Component, PropTypes } from 'react';
class Select extends Component {
constructor(props) {
super(props);
this.state = { value: props.value }; // can be initialized by <Select value='someValue' />
}
handleChange(event) {
this.setState({value: event.target.value});
}
render() {
return (
<label>
<select className="widefat" value={this.state.value} name={this.props.name} onChange={this.handleChange.bind(this)}>
<option value="grapefruit">Grapefruit</option>
<option value="lime">Lime</option>
<option value="coconut">Coconut</option>
<option value="mango">Mango</option>
</select>
</label>
);
}
}
export default Select;
走得更远
你可以在render方法中迭代一个循环来实现它,如下所示:
render() {
const dictionary = [
{ value: 'grapefruit', label: 'Grapefruit' },
{ value: 'lime', label: 'Lime' },
{ value: 'coconut', label: 'Coconut' },
{ value: 'mango', label: 'Mango' }
];
return (
<label>
<select
className="widefat"
value={this.state.value}
name={this.props.name}
onChange={this.handleChange}
>
{dictionary.map(
// Iterating over every entry of the dictionary and converting each
// one of them into an `option` JSX element
({ value, label }) => <option key={value} value={value}>{label}</option>
)}
</select>
</label>
);
}
目标事件属性返回触发事件的元素。它存储了许多属性,将其打印到控制台,熟悉其功能
import React, { Component } from 'react';
class Select extends Component {
constructor(props) {
super(props);
this.state = { value: '' };
}
handleChange = e => this.setState({ value: e.target.value });
render() {
return (
<label>
<select className="widefat" name={this.props.name} onChange={this.handleChange}>
<option value="grapefruit">Grapefruit</option>
<option value="lime">Lime</option>
<option value="coconut">Coconut</option>
<option value="mango">Mango</option>
</select>
</label>
);
}
}
export default Select;
经过长时间的搜索文档和互联网的深度,我找到了答案。我忘记为我的标签添加“for”。有我的最终代码:
import React, { Component, PropTypes } from 'react';
class Select extends React.Component {
constructor(props) {
super(props);
this.handleChange = this.handleChange.bind(this);
}
handleChange(event) {
this.setState({value: this.props.value});
}
render() {
return (
<label htmlFor={this.props.id}>{this.props.label}
<select defaultValue={this.props.value} id={this.props.id} className="widefat" name={this.props.name} onChange={this.handleChange.bind(this)}>
<option>Aucun</option>
<option value="55">Option 2</option>
<option value="126">Backend configuration & installation</option>
<option value="125">Frontend integration</option>
<option value="124">Graphic Design</option>
</select>
</label>
);
}
}
export default Select;