I'm trying to implement a biometric authentication (faceID / fingerprint) on Android using React-native with Expo.
Using the LocalAuthentication.authenticateAsync() function, the user is able to authenticate with his biometry. But if it fail, the user have to press the biometric authentication again.
So i tried a little trick with a recursif or do while loop but the result is strange :
const scanFingerPrint = async () => {
try {
const results = await DeviceService.biometricAuthentication();
if (results.success) {
SecureStoreService.getCredential()
.then(credentials => onScan(credentials));
} else {
ShakeAnimation(animatedValueModal);
return scanFingerPrint();
}
} catch (e) {
console.log(e);
}
};
With this code, if the user fail the biometric authentication, it will pass in the "else" infinitly...
So I was wondering how to handle that on android.
You can handle it manually using a variable.
First create variable retryCount inside constructor or as a property of class so that it is accessible in each function.
constructor(props) {
super(props);
this.retryCount = 3;
}
set the value of retryCount before calling scanFingerPrint function.
this.retryCount = 3; //number of attempts you want to provide
Now modify function like below to prevent infinite loop:
const scanFingerPrint = async () => {
try {
if (this.retryCount <= 0){
//exceeded the number of attempts..try again after a minute
} else{
this.retryCount--;
const results = await DeviceService.biometricAuthentication();
if (results.success) {
SecureStoreService.getCredential()
.then(credentials => onScan(credentials));
} else {
ShakeAnimation(animatedValueModal);
return scanFingerPrint();
}
}
} catch (e) {
console.log(e);
}
};
You can pass function variable for attempts.
see this,
const scanFingerPrint = async (remainingAttempts = 5) => { // you can change 5 as per your choice
try {
const results = await DeviceService.biometricAuthentication();
if (results.success) {
SecureStoreService.getCredential().then(credentials =>
onScan(credentials)
);
} else {
ShakeAnimation(animatedValueModal);
if (remainingAttempts) {
remainingAttempts--;
scanFingerPrint(remainingAttempts);
} else {
alert("You have exceeded max scan limit.");
}
}
} catch (e) {
console.log(e);
}
};
and you do not need to change anything else. not event your first time function call.
Expo provide an "error" key on the results of the local authentication. To not handle an hardware error i used this :
if (!results.success) {
switch (results.error) {
case "lockout":
setLocked(true);
break;
case "authentication_failed" || "too_fast":
ShakeAnimation(animatedValueModal);
await scanBiometric();
break;
case "user_cancel" :
break;
default:
ShakeAnimation(animatedValueModal);
break;
}
}
Related
I was trying to make an app which lists a user's repositories from github using github API, however I'm having a big problem with fetching data from all pages (so far I can only get repos from one page). I tried to fix it by using an async/await function (instead of Promise), but it's also my first time using vue3 and I have no idea how to have a function inside of the setup() method.
The current code is here:
https://github.com/agzpie/user_repos
My try at using async/await, which didn't work:
import ListElement from "./components/ListElement";
import { ref, reactive, toRefs, watchEffect, computed } from "vue";
export default {
name: "App",
components: {
ListElement,
},
setup() {
const name = ref(null);
const userName = ref(null);
const state = reactive({ data: [] });
let success = ref(null);
const userNameValidator = /^[a-z\d](?:[a-z\d]|-(?=[a-z\d])){0,38}$/i;
const split1 = reactive({ spl1: [] });
const split2 = reactive({ spl2: [] });
async function myFetch() {};
/*
* Check for input in the form and then fetch data
*/
watchEffect(() => {
if (!userName.value) return;
if (!userNameValidator.test(userName.value)) {
console.log("Username has invalid characters");
return;
}
let hasNext = false;
state.data = [];
do {
async function myFetch() {
let url = `https://api.github.com/users/${userName.value}/repos?per_page=5`;
let response = await fetch(url);
if (!response.ok) {
success.value = false;
throw new Error(`HTTP error! status: ${response.status}`);
}
success.value = true;
// check response.headers for Link to get next page url
split1.spl1 = response.headers.get("Link").split(",");
let j = 0;
while (j < split1.spl1.length) {
split2.spl2[j] = split1.spl1[j].split(";");
console.log(split2.spl2[j][0]);
console.log(split2.spl2[j][1]);
if (split2.spl2[j][1].includes("next")) {
let urlNext = split2.spl2[j][0].replace(/[<>(\s)*]/g, "");
console.log(urlNext);
url = urlNext;
hasNext = true;
break;
} else {
hasNext = false;
}
j++;
}
// second .then
let myData = await response.json();
state.data.push(...myData);
console.log("data", myData);
name.value = "";
}
myFetch().catch((err) => {
if (err.status == 404) {
console.log("User not found");
} else {
console.log(err.message);
console.log("oh no (internet probably)!");
}
});
} while (hasNext);
});
// Sort list by star count
const orderedList = computed(() => {
if (state.data == 0) {
return [];
}
return [...state.data].sort((a, b) => {
return a.stargazers_count < b.stargazers_count ? 1 : -1;
});
});
return {
myFetch,
success,
isActive: true,
name,
userName,
ListElement,
...toRefs(state),
orderedList,
};
},
};
Any help would be highly appreciated
The call to myFetch() near the end is a call to an async function without an await, so it is effectively going to loop (if hasNext was initialized to true, but it isn't) without waiting for it to complete.
You should probably change that line to await myFetch() and wrap it all with a try/catch block.
I also don't really care for the way you're directly updating state inside the async myFetch call (it could also be doing several of those if it looped) and perhaps it should be returning the data from myFetch instead, and then you can use let result = await myFetch() and then make use of that when it returns.
Also, instead of awaiting myFetch() result, you could not await it but push it onto a requests array and then use await Promise.all(requests) outside the loop and it is one operation to await, all requests running in parallel. In fact, it should probably be await Promise.allSettled(requests) in case one of them fails. See allSettled for more.
But also I wonder why you're reading it paged if the goal is to fetch them all anyway? To reduce load on the server? If that is true, issuing them paged but in parallel would probably increase the load since it will still read and return all the data but require multiple calls.
I want to clear the react native app data if my app is disconnected from internet for more than 5 min.
I am using react native NetInfo to check network connectivity status.
Saving the time when app disconnected and checking when it will reconnect to internet.
If interval is more than 5 min then I want to clear the app data.
My Code is:
class OfflineMessage extends PureComponent {
constructor(props) {
super(props);
this.state = {
isConnected: true
};
}
componentDidMount() {
NetInfo.addEventListener((state) => {
this.handleConnection(state.isConnected);
});
}
componentWillUnmount() {
NetInfo.removeEventListener((state) => {
this.handleConnection(state.isConnected);
});
}
handleConnection = (isConnected) => {
this.setState({ isConnected });
if(!isConnected){
this.startTimer();
} else {
this.checkElapsed();
}
};
startTimer = async () => {
try {
console.log('Internet disconnected at: ');
await AsyncStorage.setItem('time', JSON.stringify(Date.now()));
} catch (error) {
// console.log('Something went wrong', error);
}
}
checkElapsed = async () => {
try {
let startTime = await AsyncStorage.getItem('time');
if(startTime){
let endTime = Date.now();
const elapsedTime = Math.floor((endTime -JSON.parse(startTime))/1000);
if(elapsedTime > 5){
alert("5 min is completed.");
// Clear app data
}
console.log('Time elapsed'+ elapsedTime);
}
} catch (error) {
// console.log('Something went wrong', error);
}
}
Problem:
Both the methods startTimer and checkElapsed called whenever connectivity status changes.
What is wrong with this code.
if I modify given code as :
state = {
isConnected: true
};
componentDidMount() {
this.unsubscribeFromNetInfo = NetInfo.addEventListener((state) => {
this.handleConnection(state.isConnected);
});
}
componentWillUnmount() {
this.unsubscribeFromNetInfo();
}
handleConnection = (isConnected) => {
console.log(isConnected);
this.setState({ isConnected });
};
EventListener called multiple times and status changes frequently true false,true,false .
Now, you are handling the NetInfo subscription wrong, according to https://github.com/react-native-community/react-native-netinfo#usage
You would have to do:
componentDidMount() {
this.unsubscribeFromNetInfo = NetInfo.addEventListener(state => {
this.handleConnection(state.isConnected);
});
}
componentWillUnmount() {
this.unsubscribeFromNetInfo();
}
Also, if you want to check for 5 minutes use:
if (elapsedTime > 5 * 60)
as your conversion
Math.floor((endTime - JSON.parse(startTime)) / 1000)
converts it to seconds not minutes.
In the current state, your app will trigger almost everything as the code only checks for 5 seconds.
Otherwise, the logic that you implemented itself should be working :)
I am a beginner at react-native.
I trying to retrieve data that stored from screen1.js in Screen2.js but I failed.
I have import Asyncstorage from react-native for both .js
This how I store variable from screenone.js :
class screenone extends Component {
state = {
oldpin: '000000',
newpin: '',
secpin: '',
};
onPressButton = () => {
if (this.state.newpin == this.state.secpin) {
this.setState(
{ oldpin: this.state.newpin },
async() => await this.storeData());
}
else {
ToastAndroid.show("Password Unmatched", ToastAndroid.SHORT);
}
}
storeData = async () =>{
const {oldpin} = this.state;
let pin : oldpin;
try{
await AsyncStorage.setItem('mypin',pin);
ToastAndroid.show("Password Changed", ToastAndroid.SHORT);
}
catch (err){
console.warn(err)
}}
....
This is how I trying to retrieve data in screentwo.js:
class screentwo extends Component {
constructor(props) {
super(props);
this.onComplete = this.onComplete.bind(this);
this.state = {
pin: ''
};
}
retrieveData = async (mypin) => {
try {
let value = await AsyncStorage.getItem(mypin);
if (value !== null) {
console.log(value);
this.setState({
pin: value})
}
} catch (error) {
console.warn(err)
}
}
onComplete(inputtedPin, clear) {
retrieveData();
if (inputtedPin !== this.state.pin) {
ToastAndroid.show("Incorrect Pin", ToastAndroid.SHORT);
clear();
} else {
ToastAndroid.show("Pin is correct", ToastAndroid.SHORT);
clear();
this.props.navigation.navigate("Dashboard");
}}
....
Error:
Reference Error: ReferenceError:Can't find variable:retrieveData
Am I using the right way to stored and retrieve data?
Any suggestion?
Thank you.
There are a couple of issues that I can see with your code.
Firstly the retrieveData() function. It is asynchronous and should be called with await also you are getting the error: Reference Error: ReferenceError:Can't find variable:retrieveData because you haven't used this
So ideally you should call it await this.retrieveData();
There are a few more issues with this function. You use the parameter mypin but don't seem to pass any parameter to the function when you call it. Fixing this issue you should call retreiveData() like this:
await this.retrieveData('mypin');
Or you could remove passing the paramater altogether, which I will show how to do in my refactor below.
Finally you call retreiveData every time you check the inputtedPin this isn't that efficient, it is asynchronous so it may take some time, and secondly it also takes time for the setState function to complete, which means that the state may not have updated in time when you go to check it against the inputtedPin, meaning that you are checking the inputtedPin against the wrong value.
Code Refactor
This is how I would refactor your component.
Refactor retrieveData so that it no longer takes a parameter and the key is hardcoded in the .getItem
In the componentDidMount get the value of the pin from AsyncStorage and save it to state.
Remove the retrieveData call from onComplete
Here is the refactor
retrieveData = async () => { // parameter have been removed
try {
let value = await AsyncStorage.getItem('mypin'); // notice I am now passing the key as a string not as a parameter
if (value !== null) {
console.log(value);
this.setState({ pin: value })
}
} catch (error) {
console.warn(err)
}
}
// here we call the refactored retrievedData which will set the state.
async componentDidMount () {
await this.retrieveData();
}
onComplete(inputtedPin, clear) {
// we remove the call to retrieveData as we have already gotten the pin in the componentDidMount
if (inputtedPin !== this.state.pin) {
ToastAndroid.show("Incorrect Pin", ToastAndroid.SHORT);
clear();
} else {
ToastAndroid.show("Pin is correct", ToastAndroid.SHORT);
clear();
this.props.navigation.navigate("Dashboard");
}
}
only replace
retrieveData();
to
this.retrieveData();
When you call async method from a caller method that method also become async Try prefix
async onComplete () { await this.retrieveData() }
I am trying to use a completion handler in react-native is that possible?
pls some samples will help.
Thanks.
So i am calling this method in an instance class from a parent class, but want the method to return a value when done.
Right now its returns before the value is created but would rather like for the value to be passed once created.
getfcmToken() {
//generate token here
firebase.messaging().getToken().then(token => {
if (token) {
console.log("LOG: ", token);
_userID = token
alert(_userID)
} else {
// user doesn't have a device token yet
}
})
return this._userID;
}
I think you can just send a function as a parameter to getfcmToken. For example:
in helper/ instance class
getfcmToken(callback) {
firebase.messaging().getToken().then(token => {
if (token) {
this._userID = token;
callback({success: true, token: token};
} else {
// user doesn't have a device token yet
callback({success: false, message: 'User doesn't have device token'});
}
});
}
and then in parent class:
getUserToken() {
firebaseHelper.getfcmToken((result)=>{
if (success === true) {
//do something with token
}
});
}
How to remove an item from AsyncStorage? right now I am trying this code:
AsyncStorage.removeItem('userId');
but this is not working for me.
Try this:
async removeItemValue(key) {
try {
await AsyncStorage.removeItem(key);
return true;
}
catch(exception) {
return false;
}
}
This is what I did, had a similar issue.It works well when you want to remove an item based on its id. make sure each item has a unique id.
remove_user = async(userid) => {
try{
let usersJSON= await AsyncStorage.getItem('users');
let usersArray = JSON.parse(usersJSON);
alteredUsers = usersArray.filter(function(e){
return e.id !== userid.id
})
AsyncStorage.setItem('users', JSON.stringify(alteredUsers));
this.setState({
users:alteredUsers
})
}
catch(error){
console.log(error)
}
};
This looks correct, but maybe you are trying to read back from AsyncStorage too soon? It's asynchronous, so the change isn't applied right away and you might still see the key if you try to get it on the following line. Try to call AsyncStorage.removeItem with await or do what you want to do in the callback.
this delete method which removes object from array by passing index (here i called id)
async deleteData(id) {
try {
this.state.item.splice(id, 1);
await AsyncStorage.setItem("mylist",JSON.stringify(this.state.item))
this.setState({ item: JSON.parse(await AsyncStorage.getItem("mylist")) })
} catch (error) {
console.log(error);
}
};
and call this by using onPress method, here i am using button and pass index
<Button onPress={this.deleteData.bind(this,index)}>delete</Button>
This is the framework code for AsyncStorage.removeItem:
removeItem: function(
key: string,
callback?: ?(error: ?Error) => void
): Promise {
return new Promise((resolve, reject) => {
RCTAsyncStorage.multiRemove([key], function(errors) {
var errs = convertErrors(errors);
callback && callback(errs && errs[0]);
if (errs) {
reject(errs[0]);
} else {
resolve(null);
}
});
});
}
As you can see above it requires the key(Which is name of the item you set in asyncstorage that you want to delete) and a callback function. Make sure you have the correct key and the correct params and it should work fine.
Use removeItem() method to remove values from AsyncStorage in react.
try {
await AsyncStorage.removeItem(key);
console.log('Data removed')
}
catch(exception) {
console.log(exception)
}
try this for react-native
const deletCar = async () => {
try {
await AsyncStorage.removeItem('#storage_Key').then(() => {
// props.navigation.navigate('same page name refresh ');
/* setprevCar({ carNumner: '', carModel: '' }) return empty obj if deleted. */
})
}
catch (exception) {
return false;
}
}
if you want to remove the selected list :-
let key =[
'visitorId',
'visitorMobile',
'visitorData',
]
await AsyncStorage.multiRemove(key)