It seems like nothing is stored in the array with this code:
(Assume showList is an actual div id; didn't think it was necessary to include those tags in the code)
var i = 0;
var array = [];
var showList = document.getElementById('showList');
firebase.firestore().collection('TV Shows').get().then(snapshot => {
snapshot.forEach(doc => {
array[i] = doc.data().show.name;
i++;
//console.log(doc.data().show.name);
});
});
showList.innerHTML = array[4];
Funny enough, that commented console.log line works fine and displays all the objects, so I don't understand why I can't store it in the array. A big part of me feels as if it's my direction in using the array and/or i variable, but I tagged it as a firebase/firestore issue as well on the off chance it turns out to be a firebase issue.
If someone could point me in the write direction, I would appreciate it.
.get() is asyncronyous, and at the time you run:
showList.innerHTML = array[4];
array has not been initialized yet.
You either need to use callbacks/promises as mentioned in the linked duplicate, or simply move your call inside the .then() function:
var showList = document.getElementById('showList');
firebase.firestore().collection('TV Shows').get().then(snapshot => {
var array = [];
var i = 0;
snapshot.forEach(doc => {
array[i] = doc.data().show.name;
i++;
//console.log(doc.data().show.name);
});
showList.innerHTML = array[4];
});
Related
I'm developing a quiz/test website. I want to see different questions when I move to next question and don't want to see same answers at the same time.
I have a state array varaible which is calling allWords. This state
will keep all words.
And I have another state array variable which calls like
neverAskedWords. This state will keep words which never used
always.
I'm creating a new array variable and defining with allWords in a function. When I'm removing any record in the new array variable then that record is removing in allWords variable as well... Why?
I want to remove any record in that temporary array and want to save updated version to neverAskedWords state. In this way I could see different questions always. Here is my codes.
const [allWords, setAllWords] = useState([])
const [neverAskedWords, setNeverAskedWords] = useState([])
async function getAllData(){
axios
.get(`http://127.0.0.1:3000/api/improve-language`)
.then(res => {
setAllWords(res.data)//defining allWords
setNeverAskedWords(res.data)//defining neverAskedWords
firstQuestionAndAnswers(res.data)//sending all datas by parameter, bacause when I'm trying to get datas by using `allWords` state, it would be undefined. That's why sending all data by parameter for the first time to set first question and answers.
})
.catch(err =>{
console.log(err)
})
}
async function firstQuestionAndAnswers(wordsList){
let neverAskedList = await wordsList //creating and defining temporary variables
const allWordsList = await wordsList //creating and defining temporary variables
//some not necessary codes for this issue
const questionIndex = randomNumber(neverAskedList.length)
const firstQuestion = neverAskedList[questionIndex]
let firstAnswers = []
for (let i = 0; i < 4; i++) {
let answerIndex = randomNumber(allWordsList.length)
firstAnswers[i] = allWordsList[answerIndex]
allWordsList.splice(answerIndex, 1)//and here! I'm removing this record to prevent using it again next time, there will be different answers always
}
//some not necessary codes for this issue
firstAnswers.push(firstQuestion)
const randomisedAnswers = firstAnswers.sort(()=>Math.random() - 0.5)
//some not necessary codes for this issue
setQuestion(firstQuestion)
setAnswers(randomisedAnswers)
//and then here! I'm removing the used question in this time to prevent using it again, there will be different questions always and never see this question again
neverAskedList.splice(questionIndex, 1)
setNeverAskedWords(neverAskedList)
}
allWords should'nt change. But changing, because of why?
So the most obvious thing that I see in your code is that you are modifying the same object. What you should do instead is use the spread operator.
const [allWords, setAllWords] = useState([])
const [neverAskedWords, setNeverAskedWords] = useState([])
async function getAllData(){
axios
.get(`http://127.0.0.1:3000/api/improve-language`)
.then(res => {
setAllWords(res.data)//defining allWords
setNeverAskedWords(res.data)//defining neverAskedWords
firstQuestionAndAnswers(res.data)//sending all datas by parameter, bacause when I'm trying to get datas by using `allWords` state, it would be undefined. That's why sending all data by parameter for the first time to set first question and answers.
})
.catch(err =>{
console.log(err)
})
}
async function firstQuestionAndAnswers(wordsList){
// don't use await for js objects, should be used only with promises.
// use spread operator to make copy of the wordList array so you never actually modify the original object
let neverAskedList = [...wordsList]
const allWordsList = [...wordsList]
//some not necessary codes for this issue
const questionIndex = randomNumber(neverAskedList.length)
const firstQuestion = neverAskedList[questionIndex]
let firstAnswers = []
for (let i = 0; i < 4; i++) {
let answerIndex = randomNumber(allWordsList.length)
firstAnswers[i] = allWordsList[answerIndex]
allWordsList.splice(answerIndex, 1)//and here! I'm removing this record to prevent using it again next time, there will be different answers always
}
//some not necessary codes for this issue
firstAnswers.push(firstQuestion)
const randomisedAnswers = firstAnswers.sort(()=>Math.random() - 0.5)
//some not necessary codes for this issue
setQuestion(firstQuestion)
setAnswers(randomisedAnswers)
//and then here! I'm removing the used question in this time to prevent using it again, there will be different questions always and never see this question again
neverAskedList.splice(questionIndex, 1)
setNeverAskedWords(neverAskedList)
}
If you don't understand why it happened then here's a short explanation. In js when you do const a = { key: 'val' } you created a variable that references the memory block that is actually storing your object. And when you do const b = a you are creating another variable that references the same memory block. So updating 1 automatically changes the other one.
Within my function, through interaction from the user, I aim slowly build up an array of responses which I then pass off to an API. However, different approaches to append to the array, simply return a single position array (overwrite).
My current code as follows:
const contribution: Array = [];
const handlePress = () => {
var col = {
response,
user: 1,
update: update.id,
question: q.id,
};
contribution = [...contribution, col];
}
My understanding is that contribution = [...contribution, col] is the correct way to add to the array.
What is the best practice approach for doing this inside a function called each time the user interacts?
Although it is not clear from the question, I suspect, this code is inside a component. If so, then a new contribution array is created on every render. You need to use useState to store this array so that a new array is not created on every render.
const [contribution, setContribution] = React.useState([]);
const handlePress = () => {
var col = {
response,
user: 1,
update: update.id,
question: q.id,
};
setContribution([...contribution, col]);
}
Context:
I 'm doing a cloud function to send pushes to multiple users. I need to recover the info of each user to know some data like, name, country..etc..
Problem:
Actually I recover the list of user Id's and when I got it, then I create an array of promisesto recover all the info:
var usersPromises = []
for (var i = 0; i < usersInRange.length; i++) {
usersPromises[i] = firestore.collection("users").doc(usersInRange[i])
}
Then I recover and send the push using firestore.getAll():
firestore.getAll(...usersPromises).then(results => {
for(snapshot in results){
if(snapshot.exists){
......
var user = snapshot.data()
......
}else{
......
}
}
})
This solution is actually working "fine" almost all the time. But at this moment the Firestore db has some users that do not exist or something is wrong, because the method getAll()stops before finishing all the promises. I know it because no push is sent, and in the console, just say that the method has finished.
Reading in SO and documentation, I saw, that getAll stops if some promise is "broken". (all or nothing)
And here is where I'm lost. How can I "force" or do in another way, to just "jump" this promises that can't be completed?
P.S:
I tried to do with a "for" but It seems to omit some promises:
for (var i = 0; i < usersPromises.length; i++) {
usersPromises[i]
.get()
.then(snapshot => {
if(snapshot.exists){
......
var user = snapshot.data()
......
}else{
......
}
})
}
I think its not a problem of getAll. I have tested like this:
const firestore = new Firestore();
let doc = []
doc[0] = firestore.doc('test/test');
doc[1] = firestore.doc('test/test1');
doc[2] = firestore.doc('test/doc');
firestore.getAll(...doc)
.then(result=> result.forEach(doc => console.log(doc._fieldsProto)))
.catch(err=>console.log(err));
In my database I have 'test/test' and 'test/doc' document, but I do not have 'test/test1' and results look like this:
So we just get undefined on document that is not exist and that's all. I suggest to add catch and see if there is any exception. When I have been writing the test the function was interrupted by typo mistake in inner function.
I hope this will help!
var db=firebase.firestore();
var musicidarray=[];
var musicpaircontentarray=[];
//Retreive all music value pairs
db.collection("MusicIdNamePairs").get().then((querySnapshot) => {
querySnapshot.forEach((doc) => {
musicidarray.push(doc.id);
musicpaircontentarray.push(doc);
//alert(doc.get("Name"));
//console.log(`${doc.id} => ${doc.data()}`);
});
});
alert(musicidarray.length);//Suprisingly outputs length as zero even when the previou loop has run
for(var i=0;i<musicpaircontentarray.length;i++)
{
alert(musicpaircontentarray[i].get("Name"));
}
Here the musicidarray and the musicpaircontentarray (storing the document reference obtained from Cloud Firestore) is showing length as zero even after it has executed the push operation inside the foreach loop in the previous block of code.What is wrong here.Please help me.Thanks a lot for the help.
<script>
var db=firebase.firestore();
var musicidarray=[];
var musicpaircontentarray=[];
//Retreive all music value pairs
db.collection("MusicIdNamePairs").get().then((querySnapshot) => {
querySnapshot.forEach((doc) => {
musicidarray.push(doc.id);
musicpaircontentarray.push(doc);
//alert(doc.get("Name"));
//console.log(`${doc.id} => ${doc.data()}`);
});
displayarray();
});
function displayarray()
{
alert(musicidarray.length);
for(var i=0;i<musicpaircontentarray.length;i++)
{
alert(musicpaircontentarray[i].get("Name"));
}
}
</script>
The issue here as far as my understanding is that the array.length is called even before the data is retrieved from the database(even though the content is after the loop in the script and looks as if the length is called after only the loop is executed).Instead, call the display array method after the entire loop is assured to be completed as in the solution.
Hope this is the right way. If I am wrong somewhere, please correct me.
I am having an interesting issue. The general idea of what I am doing is pulling data from a Firebase database, and populating a table based on that data. Everything runs perfectly during initial population--cells and rows are populated as they should be, but the weird issue is that the scripts seem to execute again randomly. I've logged the incoming data to the console, and can see it print twice after some amount of time.
This second execution does not happen if I am to navigate between pages, or reload the page--in either of those cases everything works as it should. The problem SEEMS to happen when I log back into my computer after locking it??? Does anybody have ANY idea what could be going on here? Relevant portion of script below:
const table = document.getElementById('myTable');
firebase.auth().onAuthStateChanged(firebaseUser => {
if (firebaseUser) {
let user = firebase.auth().currentUser;
let uid = user.uid;
const dbRef = firebase.database().ref().child("data/" + uid);
dbRef.once('value', snap => {
var dataCount = snap.child("secondData").numChildren();
var datalist = snap.child("secondData").val();
var dataArray = Object.keys(datalist).map(function(k) {
return datalist[k]
});
pullAllInfo(dataCount, dataArray);
});
}
});
function pullAllInfo(count, array) {
let k = 0;
let dataArray = [];
for (i = 0; i < count; i++) {
let specificRef = firebase.database().ref().child("secondData/" + array[i]);
specificRef.once('value', snap => {
var optionsTag = array[k];
k++;
var dataId = snap.child("id").val();
var dataName = snap.child("name").val();
var dataCount = snap.child("data").numChildren();
dataArray.push(dataId, dataName, dataCount, optionsTag);
if (k == count) {
buildTable(dataArray);
console.log(dataArray);
}
});
}
}
As you can see from the code above I AM calling .once() for each reference, which would prevent data duplication from the typical .on() call. Just cant seem to figure this one out. ALSO I have an iMac, just for anyone curious about my potential computer unlock diagnosis.
Thanks all!
Most likely, the auth state is changing and setting off your function. Try throwing a log under firebase.auth().onAuthStateChanged like this:
firebase.auth().onAuthStateChanged(firebaseUser => {
console.log( 'auth state changed', firebaseUser );
if (firebaseUser) {
My guess is that you'll see that the AuthState is changing when you log out/log in from your computer.
I solved this issue by creating another global boolean called preLoaded. At the beginning, it is set to false and, once the data is loaded and passed off to build the table, it is set to true. It now looks like this:
if(k == count && preloaded == false){
preloaded = true;
console.log(dataArray);
buildTable(dataArray);
}
All set!