I am having an issue with async await for my AsyncStorage function within my React-native application. The error I'm getting is:
Can not use keyword 'await' outside of a async function
As you can see below, it's obvious that await is within the function. What am I doing wrong to get this error?
_retrieveData = async function (location) {
try {
var index = await AsyncStorage.getItem(location, (err, result) => result).then(result => result).catch(error=>console.log(error))
if (index !== null) {
return JSON.parse(index)
}
} catch (error) {
return null
}
};
_storeData = async function(location, value) {
try {
await AsyncStorage.set(location, JSON.stringify(value));
} catch (error) {
console.log(error)
}
};
Use ES6 arrow functions
const _retrieveData = async location => {
try {
let index = await AsyncStorage.getItem(location)
if (index !== null) {
return JSON.parse(index);
}
} catch (error) {
return null;
}
};
const _storeData = async (location, value) => {
try {
await AsyncStorage.set(location, JSON.stringify(value));
} catch (error) {
console.log(error);
}
};
Make them as an arrow functions
_retrieveData = async location => {
try {
let index = await AsyncStorage.getItem(location)
if (index !== null) {
return JSON.parse(index);
}
} catch (error) {
return null;
}
};
_storeData = async (location, value) => {
try {
await AsyncStorage.set(location, JSON.stringify(value));
} catch (error) {
console.log(error);
}
};
Related
async onDeleteProduct(id, index){
try{
const result = await this.$axios.$delete('http://localhost:8000/api/products'+id)
if(result.status){
this.products.splice(index, 1)
}
} catch(err){
console.log(err)
}
},
In my below code, I stored an object in AsyncStorage in React Native, but I have a problem reading it inside {personValue}. I got
Can't find variable personValue
Error. could you help me to run my code?
const storeData = async () => {
try {
const newperson = JSON.stringify(person);
await AsyncStorage.setItem("#Key", newperson);
alert(newperson);
} catch (e) {
}
};
const getData = async () => {
try {
const personValue = await AsyncStorage.getItem("#Key");
if (personValue !== null) {
console.log(JSON.parse(personValue));
return JSON.parse(personValue);
}
} catch (error) {
}
in the console, I can see the object correctly in GetData method
P.S: I found the mistake I made. I parsed the wrong variable.
const getData = async () => {
try {
const personValue = await JSON.parse(AsyncStorage.getItem("#Key"));
if (personValue !== null) {
console.log(personValue);
return personValue;
}
}
I'm trying to only show the disclosure screen the first time the user logs in by using AsyncStorage. Currently getData is returning a Promise and it goes straight to the landing screen on first login.
Could I get some help to get this functioning the way I want it to?
This is my login handler:
const key = 'key';
const storeData = async () => {
try {
await AsyncStorage.setItem('key', 'true');
} catch (error) {
// saving failed
console.log(error.message);
}
};
const getData = async key => {
let value = '';
try {
value = await AsyncStorage.getItem(key);
return JSON.parse(value);
} catch (e) {
console.log(error.message);
}
};
const _loginHandler = () => {
if (userName == '' || password == '') {
console.log('gagagagagagagagagagagagagagagagag');
} else {
setShowLoading(true);
const payload = {userName: userName.trim(), password: password.trim()};
setUserName('');
setPassword('');
_UserLoginHandler(payload).then(data => {
setShowLoading(false);
if (data.error) {
GlobalShowSnackBar(data.error);
} else {
setTimeout(() => {
setUserId(data);
//props.navigation.replace(getData("key")?'Landing':'Disclosure')
console.log('Key Value ' + JSON.stringify(getData('key'))); <-- this outputs Key Value {"_U":0,"_V":0,"_W":null,"_X":null}
if (getData('key')) {
props.navigation.navigate('Landing');
} else {
storeData(key);
props.navigation.navigate('Disclosure');
}
}, 500);
}
});
}
};
I got it to work with
getData('key').then(val => {
if (val) {
props.navigation.navigate('Landing');
} else {
storeData(key);
props.navigation.navigate('Disclosure');
}
});
I am working with express server and trying to read data from file and return it to different function.
My code structure looks like this:
async function getUser(req) {
fs.readFile(cfg.fileDefaults, (err, defaults) => {
do something
return user;
}
}
module.exports = {getUser}
In controller I call that function
static getTable(req, res, next) {
async function search() {
user = await getUser(req); //return undefined
getUser(req).then((a) => {
console.log(a); //second try, return undefined
})
}
search();
}
How should I call it correctly?
const fs = require('fs')
function getUser(req) {
return new Promise((resolve, reject) => {
fs.readFile(cfg.fileDefaults, (err, defaults) => {
//do something
const user = { hellow: 'world' }
resolve(user)
})
})
}
module.exports = { getUser }
In controller
static getTable(req, res, next) {
async function search() {
user = await getUser(req); // return { hellow: 'world' }
res.end(JSON.stringify(user, null, ' '))
}
search().catch((err) => {
console.log('err',err)
res.status(500)
res.end('error')
})
}
Have created React Native app and ned to use AsyncStorage to benefit from it's storage mechanism.
To save in AsyncStorage use code:
_storeData = async (param) => {
try {
let par = JSON.stringify(param);
//await AsyncStorage.setItem(this.key, par);
Utilities.setItem(this.key, par);
this._retrieveData();
} catch (error) {
console.log(JSON.stringify(error));
}
};
To retrieve data:
_retrieveData = async () => {
try {
const value = Utilities.getItem(this.key);
if (value !== null) {
alert('data is new: ' + JSON.stringify(value));
}
} catch (error) {
}
};
And, to setItem and getItem in Utilities partial:
const setItem = (key, value) => {
if (!key || !value) return;
AsyncStorage.setItem(key, value);
};
const getItem = (key) => {
if (!key) return;
var val = AsyncStorage.getItem(key);
return val;
};
Data is being saved, but response I'm getting does not look correctly, as it's a string of 'weird' characters:
{"_40":0,"_65":0,"_55":null,"_72":null}
Does anybody know why I'm getting such answer?
Note that AsyncStorage.getItem is also async - the weird characters represent the promise being returned by getItem.
Use var val = await AsyncStorage.getItem(key); and mark your getItem utility function as async. You'll need to await on any calls to Utilities.getItem and Utilities.setItem as well.