react-native array.map with asyncstorage.getItem

Question

I've been trying to retrive data from asyncstorage using react native.

Here is what i've done so far:

import React, { Component } from 'react';

import {
  Text,
} from 'react-native';

class GetData extends Component {
  constructor() {
    super()
    this.state = {
      dataLocalIds: [
        "data1Data",
        "data2Data",
        "data3Data",
        "data4Data",
        "data5Data",
        "data6Data"
      ],
    }

    this.state.dataLocalIds.map((value, index) => {
      this.data = this.getDatas(value, index);
    })
  }

  async getDatas(value, index) {
    try {
      const value = await AsyncStorage.getItem(value).then(val => {
        return JSON.parse(val)
      });
      return value
    } catch (err) {
      throw err
    }
  }

  renderScreen = () => {
      return (
        <Text> Hello World </Text>
      );
  }

  render() {
    return (
      this.renderScreen()
    );
  }
}

export default GetData;

Problem is: Apps crash with error, " the bind value at index 1 is null ".

Stacktrace does not point to lines inside my code. Instead, it points to sqlite and asyncstorage.

I really have no idea how to solve this issue. Help Would be appreciated.

Johnny Zabala · Accepted Answer · 2017-12-24 00:33:47Z

2

Hi MacFlyer have you tried using multiget (https://facebook.github.io/react-native/docs/asyncstorage.html#multiget)?

answered Dec 24, 2017 at 0:33

Johnny Zabala

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1 Comment

MacFlyer Over a year ago

I will try. Thanks!

Ishrak · Accepted Answer · 2017-12-24 05:51:49Z

0

Probably its causing due to your getData() method's argument name is value and also you are declaring a new variable const value inside the try block.

when value is passed to AsyncStorage it searches for reference to immediate scope (try block) if finds a variable is declared(JS parsing and tokenizing phase) but its value is undefined. so undefined is passed to the AsyncStorage.getItem method.

Try renaming one of those.

answered Dec 24, 2017 at 5:51

Ishrak

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Comments

Felipe Piubello · Accepted Answer · 2017-12-24 17:45:52Z

0

try something like:

constructor(){
    super();

    this.state={...}
    this.getDataFromAsyncStorage()
}
async getDataFromAsyncStorage() {
    let dataArray = [];
    for (let value of this.state.localIds){
        let data = await AsyncStorage.getItem(value);
        dataArray.push(data)
    }
    this.data = dataArray;
}

answered Dec 24, 2017 at 17:45

Felipe Piubello

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1 Comment

Felipe Piubello Over a year ago

also, adding checking if AsyncStorage found data or not is missing, but I believe this logic would not have the issues you're facing with your current code, so I guess it just needs some sharpening

Pasquale Mangialavori · Accepted Answer · 2017-12-25 10:21:23Z

0

1) this.myFunction = this.myFunction.bind(this) in the constructor could solve i think.

You have another problem.

Getdatas function is async and returns promise 2)

const promises = this.state.dataLocalIds.map((value, index) => this.getDatas(value, index));
const [data1, data2, ] = await Promise.all(promises)

3) the variable named value is already declared in geDatas scope

Try to fix and let us know

edited Dec 25, 2017 at 10:21

answered Dec 24, 2017 at 14:53

Pasquale Mangialavori

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