javascript 如何将键值对添加到状态对象 React
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How to add a key-value pair to state Object React
提问by Anna Jeanine
I'm struggling with setting the state of one of my objects in React. The code which I have:
我正在努力在 React 中设置我的一个对象的状态。我拥有的代码：
export class RRHN_App extends React.Component {
constructor(props) {
super(props);
this.startLoadingItems();
this.fetchData();
this.state = {
items: [],
itemStatus : [],
selectedItem: null,
prefsDialog: false,
preferences : {
color : "brown",
listSize : 800
}
}
}
toggleItem(item) {
console.log("Selected item: ", item);
if( this.state.selectedItem &&
item.id === this.state.selectedItem.id) {
this.setState({selectedItem: null});
} else {
let ItemID= item.id;
let newSeen = {ItemID : "seen"};
this.setState({selectedItem: item});
this.setState({itemStatus: newSeen});
}
console.log(this.state.itemStatus)
}
fetchData() {
request.get("http://localhost:3000/itemStatuses")
.end( (err,response) => {
this.setState({itemStatus: response.body})
})
}
startLoadingItems() {
request.get("http://localhost:3000/hn/topstories")
.end( (err,response) => {
this.setState({items : response.body})
})
}
}
When printing the itemStatusI get this:
打印时itemStatus我得到这个：
{16490176: "seen", 16497964: "seen", 16514428: "read", 16542395: "read", 16566536: "read"}
When the code is executed the itemStatuslooks like this:
当代码执行时，itemStatus看起来像这样：
{ItemID: "seen"}
How can I add a key-value pair of the item.id and "seen" to the state?
如何将 item.id 和“seen”的键值对添加到状态？
回答by Markus
Additionally to the dynamic key Rajesh pointed out, also note the setStatewill shallow merge existing and new state:
Try
除了 Rajesh 指出的动态键之外，还要注意setState将浅合并现有状态和新状态：尝试
this.setState({[ItemId]: 'seen'})
