AsyncStorage 以错误的格式保存数组

Question

我一直在构建一个日记应用程序，我想在 AsyncStorage 中保存这些日子，这很有效，但如果我想添加一个日子，那就太奇怪了，这就是我的功能：
这是回报： [[[{"date":"t","value":"t","name":"t"}],{"date":"p","value":"p","name":"p"}],{"date":"h","value":"h","name":"h"}]

async function createDay(date: string, journal: string, name: string) {
    try {

        try {
            const getalldays = await AsyncStorage.getItem('@journal')
            const alldays = await JSON.parse(getalldays!)

            if (JSON.parse(alldays!) !== null) {
                console.log('SHORT')
                await alldays!.push(JSON.parse(alldays!))
            }

            const newDay = { date: date, value: journal, name: name }
            await alldays.push(newDay)

            await AsyncStorage.setItem('@journal', JSON.stringify(alldays))

            const newall = await AsyncStorage.getItem('@journal')

            console.log(newall)

            return;
        } catch (error) {
            console.log(error)
            return;
        }
    } catch (err) {
        console.error(err)
    }
}

Answer 1

据我了解的问题，您希望以这种格式存储数据

[
  { date: 'h', value: 'h', name: 'h' },
  { date: 'h', value: 'h', name: 'h' },
  { date: 'h', value: 'h', name: 'h' },
  { date: 'h', value: 'h', name: 'h' },
]

我建议您为所有 Storage operations 创建一个帮助文件

第 1 步：

在您的App.js 所在的位置创建一个名为storage 的文件夹。现在在storage 文件夹中，创建一个名为AsyncStore.js 的文件，看起来应该是这样的

AsyncStore.js

import AsyncStorage from '@react-native-async-storage/async-storage';

const setData = async (token, value) => {
  try {
    await AsyncStorage.setItem(token, JSON.stringify(value));
    return true;
  } catch (e) {
    return false;
  }
};

const getData = async (token) => {
  try {
    const jsonValue = await AsyncStorage.getItem(token);
    return jsonValue != null ? JSON.parse(jsonValue) : null;
  } catch (e) {
    return null;
  }
};

const removeData = async (token) => {
  try {
    await AsyncStorage.removeItem(token);
  } catch (e) {
    return null;
  }
};

export default { setData, getData, removeData };

第 2 步：

把你的存储函数createDay改成这个

async function createDay(date, journal, name) {
  try {
    const response = await Storage.getData('@journal'); // Get last data stored

    let tempData = []; // Make a new array

    if (response) tempData = [...response]; // Copy elements if array is not null

    tempData.push({ date: 'h', value: 'h', name: 'h' }); // Push New element to array

    await Storage.setData('@journal', tempData); // Set new Array in local Storage
  } catch (err) {
    console.error(err); // Some error while storing data
  }
}

结果

我制作了一个示例 Snack here 供您查看工作实现。如果您想检查数据是否存储完好，您可以检查如下所示

import * as React from 'react';
import { Text, View, StyleSheet, Button } from 'react-native';

import AsyncStore from './storage/AsyncStore';

export default function App() {
  const [JournalData, SetJournalData] = React.useState([]);

  React.useEffect(() => {
    RestoreData(); // Restoring the last data stored here
  }, []);

  const RestoreData = async () => {
    try {
      const response = await AsyncStore.getData('@journal');
      if (response) {
        console.log(response);
        SetJournalData(response);
      }
    } catch (e) {
      console.log(e);
    }
  };

  async function createDay(date, journal, name) {
    try {
      const response = await AsyncStore.getData('@journal'); // Get last data stored

      let tempData = []; // Make a new array

      if (response) tempData = [...response]; // Copy elements if array is not null

      tempData.push({ date: 'h', value: 'h', name: 'h' }); // Push New element to array

      SetJournalData(tempData);
      await AsyncStore.setData('@journal', tempData); // Set new Array in local Storage
    } catch (err) {
      console.error(err); // Some error while storing data
    }
  }

  return (
    <View style={styles.container}>
      <Button title="Add Some Data" onPress={createDay} />
      <Text>{`Listing total ${JournalData.length} items`}</Text>
      {JournalData.map((item, index) => (
        <Text
          key={
            index
          }>{`item Number = ${index} date = ${item.date} value = ${item.value} name = ${item.name}`}</Text>
      ))}
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    backgroundColor: '#ecf0f1',
    padding: 8,
  },
});