I have a react native hook where trips must be updated every time a createdTrips is added to the state:
const [trips, setTrips] = useState([]);
function fetchCreatedTrips() {
try {
API.graphql(graphqlOperation(onCreateTrip)).subscribe({
next: (result) => {
console.log(result);
const updatedTrips = [...trips, result.value.data.onCreateTrip]
setTrips(updatedTrips)
}
})
} catch (err) { console.log(err) }
}
Now, when i first open the screen, it renders all the trips items of the list.
However with the current code, after i create a trip and go back to that screen, it doesn't currently return all the trips + the newly created one, but only one, that is the newly created one. How can i return all the items of the list? Sorry in advance, i'm a beginner.
While setting the new state on your effect you should include the previous values of the trips. You can use the spread operator to do the same.
const createdTrips = [result.value.data.onCreateTrip];
setTrips([...createdTrips, ...trips]);
or better merge the newly created trip in the updateTrips variable and then set it as the state value,
const udpatedTrips = [...trips,result.value.data.onCreateTrip];
setTrips(udpatedTrips);
The problem in your code is you are firing those two methods at the same time and there can be race conditions, so you see random updates on the screen.
Ideally, you need to bring in some consistency in the API calls and the state update. So first fetchTrips()->then->fetchCreatedTrips(). Try the below code wherein I don't update the state immediately in fetchTrips() but rather pass on the results to fetchCreatedTrips() which completes the API call and updates the state together.
const [trips, setTrips] = useState([]);
useEffect(() => {
fetchTrips();
}, [])
async function fetchTrips() {
try {
const tripData = await API.graphql(graphqlOperation(listTrips));
const trips = tripData.data.listTrips.items
fetchCreatedTrips(trips);
} catch (err) { console.log(err) }
}
function fetchCreatedTrips(fetchedTrips) {
try {
API.graphql(graphqlOperation(onCreateTrip)).subscribe({
next: (result) => {
console.log(result);
const updatedTrips = [...fetchedTrips,...updatedTrips];
setTrips(updatedTrips)
}
})
} catch (err) { console.log(err) }
}
PS: Please handle exceptions correctly.
Related
I'm trying to implement secure store (like async storage) into my testproject and it works. The only thing that doesn't work appears to be my load() useEffect that runs every time I start a new session.
So every time I start the session "null is not an object" appears and throws errors at every part where I'm looking for my list on my home-screen (my state is called goals).
but if I temporarily turn it off, add a goal to my list, and then turn it on - it works fine every time I restart the app
I feel like I need to write a condition in my load() statement but I can't figure out what, I think the app runs the load() and gets stuck at the statements where I use goals before I've added any. Can someone help me here? I've tried if (goals !== null) but it doesn't work.
const [goals, setGoals] = useState([])
const load = async() => {
if (goals !== null) {
try {
const goalsValue = await SecureStore.getItemAsync('Goals');
setGoals(JSON.parse(goalsValue))
} catch (err) {
alert(err)
}
}
}
useEffect(()=> {
load()
},[])
So what is happening is that there's nothing inside goalsValue so when you try parsing it you get an error. To avoid that you should add an if statement that checks if it's empty or not
const [goals, setGoals] = useState([])
const load = async() => {
if (goals !== null) {
try {
const goalsValue = await SecureStore.getItemAsync('Goals');
if(goalsValue) setGoals(JSON.parse(goalsValue))
}catch (err) {alert(err)}
}}
useEffect(()=> {
load()
},[])
Try this and let me know if it works ☺️
I'm doing a test app to learn react native, and I'm trying to use secure store (a bit like async storage) to store my individual goals and save them. So far it's working, however when I refresh the app only the last goal I entered gets loaded.
Where am I going wrong here? In my console log the full array is shown with both the old and the new ones I add, then I refresh and I only have one left.
const [goals, setGoals] = useState([])
const addGoal = async (goal) => {
try{
const goalJson = JSON.stringify({text: goal, id:`${Math.random()}`, todos:[], date: Date.now(), percentage:0})
await SecureStore.setItemAsync("Goal", goalJson)
load()
}
catch (err) {alert(err)}
}
const load = async() => {
try {
const goalValue = await SecureStore.getItemAsync("Goal")
const parsed = JSON.parse(goalValue)
if(goals !== null) {
setGoals([...goals, parsed])
console.log(goals)
}
}catch (err) {alert(err)}
}
useEffect(()=> {
load()
},[])
SecureStore is like a key-value database, so currently you're always writing to the same key Goal and your addGoal function is erasing the previous value with goalJson content.
Instead, load once the goals from storage, then update the goals state when a new goal is added, and write them all to on storage each time goals value is updated.
This how effects works, by "reacting" to a change of value. This is just a little bit more complicated because of SecureStorage async functions.
Here is my (untested) improved code. I renamed the storage key from Goal to Goals.
const [goals, setGoals] = useState([])
const [loaded, setLoaded] = useState(false)
useEffect(()=> {
async function load() {
try {
const goalsValue = await SecureStore.getItemAsync("Goals")
const goalsParsed = JSON.parse(goalsValue)
if (goalsParsed !== null) {
setGoals(goalsParsed)
}
setLoaded(true)
} catch (err) { alert(err) }
}
load()
}, []) // load only when component mount
const addGoal = (text) => {
const goal = { text, id:`${Math.random()}`, todos:[],
date: Date.now(), percentage:0 }
setGoals([...goals, goal])
})
useEffect(() => {
async function saveGoals() {
try {
// save all goals to storage
const goalsJson = JSON.stringify(goals)
await SecureStore.setItemAsync("Goals", goalsJson)
}
catch (err) {alert(err)}
}
if (loaded) { // don't save before saved goals were loaded
saveGoals();
}
}, [goals, loaded]) // run the effect each time goals is changed
I am trying to make an axios call to a video game database with a URL specific to the chosen option by the user. Depending on the 'opt' chosen, it will get all the data linked to the option and place into a useState ('selectedResults') as shown below
function ViewContent() {
const [selectedOpt, setSelectedOpt] = useState('none');
const opts = ["Games", "Publishers and Developers", "Reviews", "Platform"];
const [selectedResults, setSelectedResults] = useState([]);
const getGames = (selectedOpt) => {
if(selectedOpt == 'Games'){
axios.get(apiURL.games)
.then(function (response){
results = JSON.stringify(response.data.data);
setSelectedResults(response.data.data);
})
.catch(function (error){
alert(error.message)
console.log('getGameTest', error);
})
}
else if(selectedOpt == 'Publishers and Developers'){
axios.get(apiURL.creators)
.then(function (response){
// results = JSON.stringify(response.data.data);
setSelectedResults(response.data.data);
})
.catch(function (error){
alert(error.message)
console.log('getCreatorTest', error);
})
}
else if(selectedOpt == 'Reviews'){
}
};
}
The error I get is
Warning: Can't perform a React state update on an unmounted component. This is a no-op, but it indicates a memory leak in your application. To fix, cancel all subscriptions and asynchronous tasks in a useEffect cleanup function.
Is there a way I can use the useEffect cleanup for multiple axios calls or would I have to make one for each? I am trying to look over some examples but I am not getting any progress. If I missed anything, feel free to ask and I will update the question.
You might want to update react state when the component
is mounted.
export const useIsMounted = (): { readonly current: boolean } => {
const isMountedRef = React.useRef(false);
React.useEffect(() => {
isMountedRef.current = true;
return () => {
isMountedRef.current = false;
};
}, []);
return isMountedRef;
};
You can create a hook just like the above one or you can prefer useIsMounted hook from this source in order to detect if the component is mounted. Then in your case, simply do the logic below.
if(isMounted.current) {
yourSetStateAction()
}
I have a few components that can be separate or on the same page. Each of these components uses the same Vuex state. Since they can each be used on other pages and still work, each of them dispatches a call to the same Vuex action which in turns calls a service that uses axios to get the JSON data.
All of this works great!
However, when I do have 2 (or more) of these components on a single page, that axios call gets called 1 time for each of the components. Initially, I went down the path of trying to see if data existed and get created a "last got data at" timestamp so I could just bypass the 2nd call. However, these are happening both on the components created event and are being essentially called at the same time.
So, enter debounce. Seems like the exact reason for this. However, when I implement it, it fails and is passing on to the next line of code and not awaiting. What am I doing wrong?
Agenda Component (one that uses the same state)
async created() {
await this.gatherCalendarData();
},
methods: {
async gatherCalendarData() {
await this.$store.dispatch('time/dateSelected', this.$store.state.time.selectedDate);
},
},
Month Component (another, notice they are the same)
async created() {
await this.gatherCalendarData();
},
methods: {
async gatherCalendarData() {
await this.$store.dispatch('time/dateSelected', this.$store.state.time.selectedDate);
},
},
The Action getting called
async dateSelected(context, data) {
let result = await getCalendarData(isBetween.date, context.rootState.userId);
await context.commit('SET_MONTHLY_DATA', { result: result.Result, basedOn: isBetween.date });
},
This getCalendarData method is in a service file I created to make api calls (below.)
This is the error that I receive (once for each component) that calls this action.
[Vue warn]: Error in created hook (Promise/async): "TypeError: Cannot read property 'Result' of undefined"
Which is referring to the 3rd line above: result: result.Result
API Service
const getCalendarData = debounce(async (givenDate, userId) => {
let response = await getCalendarDataDebounced(givenDate, userId);
return response;
}, 100);
const getCalendarDataDebounced = async (givenDate, userId) => {
let result = await axiosGet('/api/v2/ProjectTime/BuildAndFillCalendarSQL', {
givenDate: givenDate,
userID: userId,
});
return result;
};
Axios Wrapper
const axiosGet = async (fullUrl, params) => {
let result = null;
try {
let response = await axios.get(fullUrl, params ? { params: params } : null);
result = await response.data;
} catch(error) {
console.error('error:', error);
}
return result;
};
If I put console.log messages before, after and inside the getCalendarData call as well as in the getCaledarDataDebounced methods: (assuming just 2 components on the page) the 2 before logs show up and then the 2 after logs appear. Next the error mentioned above for each of the 2 components, then a single 'inside the getCalendarData' is logged and finally the log from within the debounced version where it actually gets the data.
So it seems like the debouncing is working in that it is only run a single time. But it appears that await call let result = await getCalendarData(isBetween.date, context.rootState.userId); is not truly Waiting.
Am I missing something here?
EDITS after Answer
Based on #JakeHamTexas' answer, my action of dateSelected is now (actual full code, nothing removed like above as to not confuse anything):
async dateSelected(context, data) {
console.log('dateSelected action');
let isBetween = isDateWithinCurrentMonth(data, context.state);
if (!isBetween.result) {
// The date selected is in a different month, so grab that months data
return new Promise(resolve => {
getCalendarData(isBetween.date, context.rootState.userId)
.then(result => {
console.log('inside promise');
context.commit('SET_MONTHLY_DATA', { result: result.Result, basedOn: isBetween.date });
context.commit('SET_SELECTED_DATE', isBetween.date);
context.commit('statistics/TIME_ENTRIES_ALTERED', true, { root: true });
resolve();
});
});
} else {
// The date selected is within the given month, so simply select it
context.commit('SET_SELECTED_DATE', data);
}
context.commit('CLEAR_SELECTED_TIME_ENTRY_ID');
},
And my API call of getCalendarData is now:
const getCalendarData = async (givenDate, userId) => {
console.log('getting calendar data');
let result = await axiosGet('/api/v2/ProjectTime/BuildAndFillCalendarSQL', {
givenDate: givenDate,
userID: userId,
});
return result;
};
The error is gone! However, it does not seem to be debouncing - meaning everything gets called 3 times. I would expect the dateSelected action to be called 3 times. But I would like to avoid the getting calendar data being called 3 times. If it helps, this is what the console looks like:
dateSelected action
getting calendar data
dateSelected action
getting calendar data
dateSelected action
getting calendar data
inside promise
inside promise
inside promise
You need to return a promise from your action. Returning a promise of undefined (which is what is currently happening) resolves immediately.
dateSelected(context, data) {
return new Promise(resolve => {
getCalendarData(isBetween.date, context.rootState.userId)
.then(result => {
context.commit('SET_MONTHLY_DATA', { result: result.Result, basedOn: isBetween.date });
resolve();
}
}
},
Additionally, a vuex commit does not return a promise, so it doesn't make sense to await it.
export const USER_KEY = "isLoggedIn";
export const phoneVerified = () => AsyncStorage.setItem(USER_KEY, 1);
export const userInfoVerified = () => AsyncStorage.setItem(USER_KEY, 2);
I have used the above functions to store the value and the below one to get the value.
export const isSignedIn = () => {
return new Promise((resolve, reject) => {
AsyncStorage.getItem(USER_KEY)
.then(res => {
console.log("from isSignedIn : "+res); //res is showing null.
if (res !== null) {
resolve(res);
} else {
resolve(0);
}
})
.catch(err => reject(err));
});
};
Why this always returns null? I was trying async/await but still getting null. I think somehow the data is not storing.
I'm afraid you can only store strings. Please refer to this React Native AsyncStorage storing values other than strings and this https://facebook.github.io/react-native/docs/asyncstorage.html#setitem
Thanks.
As answered by #Vishu Bhardwaj AsyncStorage accepts only string. So you can use JSON.stringify() and JSON.parse() in such cases.
I was stuck with this stupid problem for almost one week, no other way that is suggested in all communities worked for me, but then I found something that is built of react-native which its setState() callback function: https://medium.learnreact.com/setstate-takes-a-callback-1f71ad5d2296.
so the only way that I guarantee that it's the only secure way so far is this that u use the setState() function in your promise and everything that you need to run, put them on a function and call it for the setState() callback function , this is only way you can make sure yourself that you neither get null nor never calling the function . Here I'm going to provide an example of it which this.tokeToServer() is my function which it's used as a callback function.
try {
AsyncStorage.getItem('firebase_token',(err,item) => {
if (item) {
this.setState({
firebase_token: item,
}),this.tokenToServer();
}
});
} catch (error) {
console.log("Error retrieving data" + error);
}
As presented by friend Abdu4, I had the same problem for 4 days and searching for different sites and forums. Attempts with async/await and others, even though you should use these options, the one you completed and really worked was to assign the value through setState by callback
try {
AsyncStorage.getItem('TOKEN_KEY',(err,item) => {
if (item) {
setToken({
Token: item,
});
}
});
} catch (error) {
console.log("Error retrieving data" + error);
}