背景
我将根据选择框中的值过滤表格。我无法理解state
中的props
和react.js
。一旦我传递了值,我就可以轻松地进行过滤,但我试图以“反应”的方式做到这一点。
问题
当用户选择其中一个选项时,如何在选中SelectionBox
时将其传递给TableDisplay
?
示例
class SelectionBox extends React.Component {
render() {
return <div className="filter">
<label for="business">Filter by Status
<select id="business" name="business">
<option value="all">All Requests</option>
<option value="approved">Approved</option>
<option value="pending">Pending</option>
<option value="denied">Denied</option>
</select>
</label>
</div>;
}
}
class TableDisplay extends React.Component {
render() {
return <div className="wrapper">
<h1>Requests</h1>
<SelectionBox />
<div><table className="table">
<tr className="seperate"><td>Title</td><td>Status</td><td>Created</td><td>Updated</td><td>Delete</td></tr>
{Object.keys(requests).map(function(key) {
let styling = "bg-plain";
if (requests[key].status == "Approved") {
styling = "bg-success";
} else if (requests[key].status == "Denied") {
styling = "bg-danger";
}
return <tr className={styling}>
<td>{requests[key].title}</td>
<td>{requests[key].status}</td>
<td>{requests[key].created_at.slice(0, 10)}</td>
<td>{requests[key].updated_at.slice(0, 10)}</td>
<td><a href="">Delete</a></td>
</tr>;
})}
</table>
</div></div>;
}
}
研究
从阅读中我认为我需要在这里实现的是,
在SelectionBox
constructor(props) {
super(props);
this.state = {
// Something referring to the state of the select box here
};
};
然后从props
内访问TableDisplay
?
答案 0 :(得分:1)
首先,为了清楚您对state
vs props
的理解,您应该参考以下答案:What is the difference between state and props in React?
其次,要将SelectionBox
的值传递给TableDisplay
,您需要创建包含两个组件的某种父TableDisplayContainer
组件。 TableDisplayContainer
会将select
下拉列表的值存储在其状态中。要执行此操作,您需要将作为道具的函数传递给SelectionBox
,以处理onChange
下拉列表的select
事件(例如,您可以将其称为handleOnChange
)。 handleOnChange
方法会将值设置为TableDisplayContainer
的状态。一旦设置为状态,您可以将值作为道具传递给TableDisplay
组件。
以下是您可以做的快速示例:
class SelectionBox extends React.Component {
render() {
return (
<div className="filter">
<label for="business">Filter by Status
<select
id="business"
name="business"
onChange={this.props.handleOnChange}
>
<option value="all">All Requests</option>
<option value="approved">Approved</option>
<option value="pending">Pending</option>
<option value="denied">Denied</option>
</select>
</label>
</div>
);
}
}
class TableDisplay extends React.Component {
render() {
// Do your filtering with this value
const {selectValue} = this.props;
return (
<div className="wrapper">
<h1>Requests</h1>
<SelectionBox />
<div><table className="table">
<tr className="seperate"><td>Title</td><td>Status</td><td>Created</td><td>Updated</td><td>Delete</td></tr>
{Object.keys(requests).map(function(key) {
let styling = "bg-plain";
if (requests[key].status == "Approved") {
styling = "bg-success";
} else if (requests[key].status == "Denied") {
styling = "bg-danger";
}
return <tr className={styling}>
<td>{requests[key].title}</td>
<td>{requests[key].status}</td>
<td>{requests[key].created_at.slice(0, 10)}</td>
<td>{requests[key].updated_at.slice(0, 10)}</td>
<td><a href="">Delete</a></td>
</tr>;
})}
</table>
</div>
</div>
);
}
}
class TableDisplayContainer extends React.Component {
constructor() {
super();
this.state = {
selectValue: 'all' // use this as default
}
}
handleOnChange(e) {
this.setState({
selectValue: e.target.value
});
}
render() {
const {selectValue} = this.state;
return (
<div>
<SelectionBox
handleOnChange={this.handleOnChange.bind(this)}
/>
<TableDisplay
selectValue={selectValue}
/>
</div>
)
}
}
答案 1 :(得分:0)
On React状态是与组件本身相关的东西,并且props向下传递给它(或者在遗漏的情况下具有默认值)。 handle events guide解释了我的解决方案:
您可以将onChange处理程序传递给selectionBox并在TableDisplay组件上使用它
class SelectionBox extends React.Component {
render () {
//...
<select onChange={this.props.onChange}>
//...
</select>
//...
}
}
SelectionBox.propTypes = {
onChange: PropTypes.func.isRequired
}
class TableDisplay extends React.Component {
constructor(props) {
super(props)
this.onSelection = this._onSelection.bind(this)
this.state = {
selectValue: null
}
}
_onSelection (ev) {
this.setState({selectValue:ev.target.value})
}
render () {
//...
<SelectionBox onChange={this.props.onSelection} />
//...
<h1>{'The select value is '+ this.state.selectValue}</h1>
}
}
请注意,我使用propTypes只是为了确保我不会忘记。