我正在研究基于React.js的大纲(与workflowy类似)。我被困在一个点上。当我按下任何一个项目上的输入时,我想在其下方插入另一个项目。React.js无法在状态更新上重新呈现应用
因此,我已经使用的setState函数来插入项目只是当前项如以下所示通过下面的代码片断:
this.setState({
items: this.state.items.splice(this.state.items.map((item) => item._id).indexOf(itemID) + 1, 0, {_id: (new Date().getTime()), content: 'Some Note'})
})
然而,应用程序被重新呈现没有任何错误显示为空白。
我的全部源至今:
import './App.css';
import React, { Component } from 'react';
import ContentEditable from 'react-contenteditable';
const items = [
{
_id: 0,
content: 'Item 1 something',
note: 'Some note for item 1'
},
{
_id: 5,
content: 'Item 1.1 something',
note: 'Some note for item 1.1'
},
{
_id: 1,
content: 'Item 2 something',
note: 'Some note for item 2',
subItems: [
{
_id: 2,
content: 'Sub Item 1 something',
subItems: [{
_id: 3,
content: 'Sub Sub Item 4'
}]
}
]
}
];
class App extends Component {
render() {
return (
<div className="App">
<Page items={items} />
</div>
);
}
}
class Page extends Component {
constructor(props) {
super(props);
this.state = {
items: this.props.items
};
this.insertItem = this.insertItem.bind(this);
}
render() {
return (
<div className="page">
{
this.state.items.map(item =>
<Item _id={item._id} content={item.content} note={item.note} subItems={item.subItems} insertItem={this.insertItem} />
)
}
</div>
);
}
insertItem(itemID) {
console.log(this.state.items);
this.setState({
items: this.state.items.splice(this.state.items.map((item) => item._id).indexOf(itemID) + 1, 0, {_id: (new Date().getTime()), content: 'Some Note'})
})
console.log(this.state.items);
}
}
class Item extends Component {
constructor(props) {
super(props);
this.state = {
content: this.props.content,
note: this.props.note
};
this.saveItem = this.saveItem.bind(this);
this.handleKeyPress = this.handleKeyPress.bind(this);
}
render() {
return (
<div key={this.props._id} className="item">
<ContentEditable html={this.state.content} disabled={false} onChange={this.saveItem} onKeyPress={(event) => this.handleKeyPress(this.props._id, event)} />
<div className="note">{this.state.note}</div>
{
this.props.subItems &&
this.props.subItems.map(item =>
<Item _id={item._id} content={item.content} note={item.note} subItems={item.subItems} insertItem={this.insertItem} />
)
}
</div>
);
}
saveItem(event) {
this.setState({
content: event.target.value
});
}
handleKeyPress(itemID, event) {
if (event.key === 'Enter') {
event.preventDefault();
console.log(itemID);
console.log(event.key);
this.props.insertItem(itemID);
}
}
}
export default App;
GitHub的回购:https://github.com/Hirvesh/mneme
任何人可以帮助我理解,为什么它不会再次渲染后,我更新的项目?
编辑:
我有更新的代码,添加键,下面的建议,仍然呈现为空白,尽管状态更新:
import './App.css';
import React, { Component } from 'react';
import ContentEditable from 'react-contenteditable';
const items = [
{
_id: 0,
content: 'Item 1 something',
note: 'Some note for item 1'
},
{
_id: 5,
content: 'Item 1.1 something',
note: 'Some note for item 1.1'
},
{
_id: 1,
content: 'Item 2 something',
note: 'Some note for item 2',
subItems: [
{
_id: 2,
content: 'Sub Item 1 something',
subItems: [{
_id: 3,
content: 'Sub Sub Item 4'
}]
}
]
}
];
class App extends Component {
render() {
return (
<div className="App">
<Page items={items} />
</div>
);
}
}
class Page extends Component {
constructor(props) {
super(props);
this.state = {
items: this.props.items
};
this.insertItem = this.insertItem.bind(this);
}
render() {
return (
<div className="page">
{
this.state.items.map(item =>
<Item _id={item._id} key={item._id} content={item.content} note={item.note} subItems={item.subItems} insertItem={this.insertItem} />
)
}
</div>
);
}
insertItem(itemID) {
console.log(this.state.items);
this.setState({
items: this.state.items.splice(this.state.items.map((item) => item._id).indexOf(itemID) + 1, 0, {_id: (new Date().getTime()), content: 'Some Note'})
})
console.log(this.state.items);
}
}
class Item extends Component {
constructor(props) {
super(props);
this.state = {
content: this.props.content,
note: this.props.note
};
this.saveItem = this.saveItem.bind(this);
this.handleKeyPress = this.handleKeyPress.bind(this);
}
render() {
return (
<div className="item">
<ContentEditable html={this.state.content} disabled={false} onChange={this.saveItem} onKeyPress={(event) => this.handleKeyPress(this.props._id, event)} />
<div className="note">{this.state.note}</div>
{
this.props.subItems &&
this.props.subItems.map(item =>
<Item _id={item._id} key={item._id} content={item.content} note={item.note} subItems={item.subItems} insertItem={this.insertItem} />
)
}
</div>
);
}
saveItem(event) {
this.setState({
content: event.target.value
});
}
handleKeyPress(itemID, event) {
if (event.key === 'Enter') {
event.preventDefault();
console.log(itemID);
console.log(event.key);
this.props.insertItem(itemID);
}
}
}
export default App;
编辑2:
根据以下建议,如果有人想看看,添加的键= {i._id},仍然不起作用,会将最新的代码推送到github。
this.state.items.map((item, i) =>
<Item _id={item._id} key={i._id} content={item.content} note={item.note} subItems={item.subItems} insertItem={this.insertItem} />
)
如果您对代码进行格式化并使其更具可读性,将会更容易。如果可能,您也可以删除任何未使用的代码。 – nem035
单独检查长的不可读代码行: 'const newItems = this.state.items.splice(this.state.items.map((item)=> item._id).indexOf(itemID)+ 1,0,{ _id:(new Date().getTime()),content:'Some Note'})' 'this.setState({items:newItems})' – webdeb
我做了,项目状态对象更新就好了,项目被添加,但该应用程序重新渲染为空 – Hirvesh