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在 react native 中，如何使用 FlatList 自定义警报文本数组。

如果单击第一个项目，我想显示警报标题的“警报优先”。

但是很难在 ALERT_TITLE 和 props{id} 之间同步 id。

多次失败后，我需要堆栈溢出。

请回答我的问题。

下面是我的代码和来自https://reactnative.dev/docs/0.60/flatlist的参考

我不确定 const array set const ALERT_TITLE = {'Alert First', 'Alert Second', 'Alert Third'}; 或 const ALERT_TITLE = [{id: 'aa', title: 'Alert First ',},{id: 'bb', title: 'Alert Second ',},{id: 'cc', title: 'Alert Third ' ,},];

const ALERT_TITLE = [
  {id: 'aa', title: 'Alert First ',},
  {id: 'bb', title: 'Alert Second ',},
  {id: 'cc', title: 'Alert Third ',},
];
const ALERT_MESSAGE = [
  {id: 'aa', title: 'msg First ',},
  {id: 'bb', title: 'msg Second ',},
  {id: 'cc', title: 'msg Third ',},
];

const DATA = [
  {id: 'aa', title: 'First Item',},
  {id: 'bb', title: 'Second Item',},
  {id: 'cc', title: 'Third Item',},
];

function Item({ id, title, selected, onSelect }) {
  return (
    <TouchableOpacity
      onPress={() => Alert.alert(
        ALERT_TITLE.toDoSomeThing,//{if first item click I wanna show 'Alert First'}
        ALERT_MESSAGE.toDoSomeThing,//{if first item click I wanna show 'msg First'}
        [
          { text: 'Cancel'},
          { text: 'OK', onPress: () => onSelect(id)}
        ],
        { cancelable: false }
      )}

      style={[
        styles.item,
        { backgroundColor: selected ? '#6e3b6e' : '#f9c2ff' },
      ]}
    >
      <Text style={styles.title}>{title}</Text>
    </TouchableOpacity>

  );
}

export default function App() {
  const [selected, setSelected] = React.useState(new Map());

  const onSelect = React.useCallback(
    id => {
      const newSelected = new Map(selected);
      newSelected.set(id, !selected.get(id));

      setSelected(newSelected);
    },
    [selected],
  );

  return (
    <SafeAreaView style={styles.container}>
      <FlatList
        data={DATA}
        renderItem={({ item }) => (
          <Item
            id={item.id}
            title={item.title}
            selected={!!selected.get(item.id)}
            onSelect={onSelect}
          />
        )}
        keyExtractor={item => item.id}
        extraData={selected}
      />
    </SafeAreaView>
  );
}
4

1 回答 1

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ALERT_MESSAGE 和 ALERT_TITLE 是数组，因此它们不提供 ALERT_TITLE.toDoSomeThing 或 ALERT_MESSAGE.toDoSomeThing 访问器。

要显示所需的文本，您应该在 ALERT_TITLE 和 ALERT_MESSAGE 数组中找到所需的项目，并从中访问字段，如下所示

function Item({ id, title, selected, onSelect }) {
  return (
    <TouchableOpacity
      onPress={() => Alert.alert(
        ALERT_TITLE.find(el => el.id === id).title,//{if first item click I wanna show 'Alert First'}
        ALERT_MESSAGE.find(el => el.id === id).title,//{if first item click I wanna show 'msg First'}
        [
          { text: 'Cancel'},
          { text: 'OK', onPress: () => onSelect(id)}
        ],
        { cancelable: false }
      )}

      style={[
        styles.item,
        { backgroundColor: selected ? '#6e3b6e' : '#f9c2ff' },
      ]}
    >
      <Text style={styles.title}>{title}</Text>
    </TouchableOpacity>

  );
}

另一种方法（比这个更快）是将项目的索引传递给 Item 组件，如下所示：

您的平面清单声明变为：

<FlatList
    data={DATA}
    renderItem={({ item, index }) => (
      <Item
        id={item.id}
        title={item.title}
        selected={!!selected.get(item.id)}
        onSelect={onSelect}
        index={index}
      />
    )}
    keyExtractor={item => item.id}
    extraData={selected}
    />

并且您的 Item 组件通过道具获取索引

function Item({ id, title, selected, onSelect, index }) {
  return (
    <TouchableOpacity
      onPress={() => Alert.alert(
        ALERT_TITLE[index].title,//{if first item click I wanna show 'Alert First'}
        ALERT_MESSAGE[index].title,//{if first item click I wanna show 'msg First'}
        [
          { text: 'Cancel'},
          { text: 'OK', onPress: () => onSelect(id)}
        ],
        { cancelable: false }
      )}

      style={[
        styles.item,
        { backgroundColor: selected ? '#6e3b6e' : '#f9c2ff' },
      ]}
    >
      <Text style={styles.title}>{title}</Text>
    </TouchableOpacity>

  );
}
于 2020-08-15T14:05:58.017 回答