React-Native中的FlatList學習記錄(三)之keyExtractor值不唯一造成的錯誤
寫作時間:2021/9/22
React-Native版本:0.63.2
目标平台:Android、iOS
開發過程中遇到的一個錯誤,最後發現是由于資料源有兩個item具有相同的key值,代碼如下
//App.js
'use strict';
import React from 'react';
import List from './demos/demo_1/List';
export default class App extends React.Component {
render() {
return (
<List />
);
}
}
//List.js
'use strict';
import React from 'react';
import { FlatList, Button, SafeAreaView } from 'react-native';
import Item from './Item';
export default class List extends React.Component {
constructor() {
super();
this.state = {
list: [
{ number: '11111111', data: { id: '1', name: 'aaa', age: 11 } },
{ number: '22222222', data: { id: '1', name: 'bbb', age: 22 } },
{ number: '33333333', data: { id: '3', name: 'ccc', age: 33 } },
],
};
}
render() {
return (
<SafeAreaView>
<Button title={'button'} onPress={this.onButtonPress} />
<FlatList data={this.state.list} renderItem={this.renderItem} keyExtractor={this.keyExtractor} />
</SafeAreaView>
);
}
renderItem = ({ item }) => {
return <Item itemData={item} />;
};
keyExtractor = (item) => item.data.id;
onButtonPress = () => {
this.setState({
list: [
{ number: '44444444', data: { id: '4', name: 'ddd', age: 44 } },
{ number: '55555555', data: { id: '5', name: 'eee', age: 55 } },
],
});
};
}
//Item.js
'use strict';
import React from 'react';
import { Text } from 'react-native';
export default class Item extends React.Component {
render() {
return <Text>{this.props.itemData.data.name}</Text>;
}
}
根據代碼不難看出,對清單資料進行了替換,希望替換之後的展示資料由3項變為2項,但實際現象如下
點選前
點選後
記錄一下,以後開發過程中需要避免出現類似情況