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Resolve promise inside javascript map function

I have gone through several questions and posts regarding how to accomplish this but none have worked. I have tried an array (no pun intended) of possible solutions involving
Promise.*, thenable, await and none have worked.
I have an array of payments that I extract from a Prisma db call, the object looks like this:
[{
"id": 1,
"amount": 100,
"payment_data": [{
"credits": 2,
"subscription_id": 534
}, {
"credits": 3,
"subscription_id": 469
}],
"customerId": 14
}]
I am trying to run another database query using the subscription_id under each payment_data for which I built a simple function:
const get_subscription = async function (subscription_id) {
return await db.subscriptions.findUnique({
where: {
id: Number(subscription_id)
}
})
}
And then I execute it inside a .map like this:
const mapped_payments = payments.map((payment) => ({
...payment,
payment_data: payment.payment_data.map(function (data) {
data.subscription = get_subscription(data.subscription_id).then((resp => resp))
return data
})
}))
The problem is no matter what I have tried this never resolves.
If I console log mapped_payments the subscription object shows as Promise {<pending>} and entirely empty when I return the response in express.
I am sure this is a simple solution but I have moved all possible solutions (Promise.*, thenable, await) into the function, into the .map and into the res.send but none work.
Any help is appreciated!

You need to use async map callback to await the get_subscription function, Also it would be better to use Promise.all to handle all mapped promises.
const mapped_payments = await Promise.all(payments.map(async (payment) => ({
...payment,
payment_data: await Promise.all(payment.payment_data.map(async function (data) {
data.subscription = await get_subscription(data.subscription_id)
return data
}))
})))

Handling dependent react queries

I have two react queries in the same component
const { data: sdrData, status: sdrDataLoading } = useQuery(
[queryInfo[0]?.dcsSysId, data[0]?.dcsStructSysId, data[cardIndex]?.dcsStructNodeId],
() => getSDR(queryInfo[0]?.dcsSysId, data[0]?.dcsStructSysId, data[cardIndex]?.dcsStructNodeId),
);
const { isIdle, data: sdrTemplateData, status: sdrTemplateDataLoading } = useQuery(
[sdrData[0]?.dcsSdrSysId, queryInfo[0]?.fldTemplateSysId],
() =>
SDRTemplateValues(sdrData[0]?.dcsSdrSysId, queryInfo[0]?.fldTemplateSysId, {
// The query will not execute until the userId exists
enabled: !!sdrData[0]?.dcsSdrSysId,
retry: true,
}),
);
My second query is depended on the first I need to access sdrData[0] for the first arg in my query however when I do this the query is undefined initially and it fails. Is there a good way to handle this. I saw you can set it equal to a variable, but I'm still faced with the same problem.
I need a way to tell the first query to wait until the second query is finished before it tried to access the arguments. I thought you could set enabled like I did, but that didn't work either.

I was able to solve this by adding the data parameter I need to the beginning of the argument array like this.
const { data: sdrData, status: sdrDataLoading } = useQuery(
queryInfo[0]?.dcsSysId && [
queryInfo[0]?.dcsSysId,
data[0]?.dcsStructSysId,
data[cardIndex]?.dcsStructNodeId,
],
() => getSDR(queryInfo[0]?.dcsSysId, data[0]?.dcsStructSysId, data[cardIndex]?.dcsStructNodeId),
);
const { data: sdrTemplateData, status: sdrTemplateDataLoading } = useQuery(
sdrData?.[0]?.dcsSdrSysId && [sdrData?.[0]?.dcsSdrSysId, queryInfo[0]?.fldTemplateSysId],
() => SDRTemplateValues(sdrData?.[0]?.dcsSdrSysId, queryInfo[0]?.fldTemplateSysId),
);

You are on the right path here.
You just need to check if sdrData is undefined. You are trying to access the first element (sdrData[0]) but initially it's undefined.
...
{
enabled: !!(sdrData && sdrData[0]?.dcsSdrSysId
}
...

Unable to get data from created() to data() in VueJS 2

I am fetching data from API inside the created method and i want to use these data in the page.
Here is my code.
created(){
let id = this.$route.params.id
let videos;
this.$axios.get(this.$axios.defaults.apiURL + 'v1.0.0/tips/' +id,).then((response) => {
this.videos = response.data.data;
}, (error) => {
toast.$toast.error('Something went wrong! Please try again', {
position: 'top'
})
});
},
data(){
let videos = this.videos;
return {
video: {
sources: [{
src: videos.video_url,
type: 'video/mp4'
}],
options: {
autoplay: true,
volume: 0.6,
poster: videos.thumbnail
}
}
}
}
I am getting error that thumbnail and video_url is not defined. This 2 values are coming from API response. How can i solve this? Thanks

I can see two obvious issues with your code (without seeing it in action):
created is a synchronous hook, but your axios request is returning a promise. Instead of waiting for the promise, you are immediately trying to show the result, hence the issue you are encountering - the data just hasn't arrived yet.
Your use of this seems a bit chaotic (i.e. let videos = this.videos - where would this.videos come from? The only other 'videos' is declared inside of a different function with let)
There are multiple ways to solve this, depending on what you want to show while you are fetching the data and what type of component this is - if you want to show a spinner while you are waiting for the request to be answered, or if you just want to show some progress bar on the previous page and only enter this one once it's loaded.
In-component loading
In the first case, I would suggest setting a variable or using a loader management solution like vue-wait. Your code could look like this then:
data() {
return {
loading: true,
videos: null,
}
},
computed: {
video() {
return this.videos ? {
sources: [{
src: this.videos.video_url,
type: 'video/mp4'
}],
options: {
autoplay: true,
volume: 0.6,
poster: this.videos.thumbnail
}
} : null
}
},
methods: {
fetch() {
let id = this.$route.params.id
this.$axios.get(this.$axios.defaults.apiURL + 'v1.0.0/tips/' + id, ).then((response) => {
this.videos = response.data.data;
}, (error) => {
toast.$toast.error('Something went wrong! Please try again', {
position: 'top'
})
}).finally(() => (this.loading = false));
},
},
created() {
this.fetch()
},
In your template, you would add somewhere v-if=!loading to make sure that the request has finished before you try to show something
Data-fetching before entering page
If this is a page though, you could request the data in beforeRouteEnter - there's a whole article that explains the principle on the vue site

How to use async data for use with chart.js in ionic

I am calling some data in via an api for an ionic app I'm making. The data is being called asynchronously and I need to assign the data to different variables for use in a chart that gets presented to the user. I'm struggling to assign the data to a variable that I can then access from the function which creates the chart (I'm using chart.js). Initially I've been trying to grab a list of dates from the data for use as the X axis scale, just to get things working.
Been trying quite a few things and failing. I initially thought it was because my variable was block scoped, but now I think its an async issue. Been reading about promises for hours, but although I understand the concept I can't see away to apply it to my current code (presuming the issue is async! I'm a noob on a self teaching mission here).
So this the code which handles pulling in the data from the api
async getData() {
const loading = await this.loadingController.create({
message: 'Loading'
});
await loading.present();
this.api.getData()
.subscribe(res => {
console.log(res);
this.data1 = res[0];
loading.dismiss();
console.log(this.data1);
const datelabel = this.data1.result[1].date;
}, err => {
console.log(err);
loading.dismiss();
});
}
And this is the code which creates the chart
useAnotherOneWithWebpack() {
var ctx = (<any>document.getElementById('canvas-linechart')).getContext('2d');
console.log('GotData', this.datelabel); //just to see what data I've got here if any in the console
var chart = new Chart(ctx, {
// The type of chart we want to create
type: 'line',
// The data for our dataset
data: {
labels: this.datelabel,
datasets: [{
data: [86,114,106],
label: "Africa",
borderColor: "#3e95cd",
fill: false
}, {
data: [282,350,411],
label: "Asia",
borderColor: "#8e5ea2",
fill: false
}, {
data: [168,170,178],
label: "Europe",
borderColor: "#3cba9f",
fill: false
}
]
},
options: {
title: {
display: true,
text: 'World population per region (in millions)'
}
}
});
}
So I'm calling the datalabel variable against labels, but its displaying as undefined on the axis and in the console. I'm expecting to see three months (which are saved as strings in the variable). Tried all sorts now and its driving me a bit mad. I'm not even sure its an async issue, but from what I've done so far it feels like the issue.
Any help really appreciated!!

Not sure when/where you're calling the useAnotherOneWithWebpack() method but one issue from your code is that you're assigning some values to the local constant datelabel but not to the property from the component:
// The following line just creates a local const available only in that scope
const datelabel = this.data1.result[1].date;
Instead, you should be initializing the component's property:
this.datelabel = this.data1.result[1].date;
Keeping that in mind, please try the following:
async getData() {
const loading = await this.loadingController.create({
message: 'Loading'
});
await loading.present();
this.api.getData().subscribe(
res => {
// This line will be executed when getData finishes with a success response
console.log('Inside of the subscribe - success');
console.log(res);
this.data1 = res[0];
this.datelabel = this.data1.result[1].date;
// Now that the data is ready, you can build the chart
this.useAnotherOneWithWebpack();
loading.dismiss();
},
err => {
// This line will be executed when getData finishes with an error response
console.log('Inside of the subscribe - error');
console.log(err);
loading.dismiss();
});
// This line will be executed without waiting for the getData async method to be finished
console.log('Outside of the subscribe');
}

nodejs recursively call same api and write to excel file sequentially

I need to call an API recursively using request promise after getting result from API need to write in an excel file , API sample response given below
{
"totalRecords": 9524,
"size": 20,
"currentPage": 1,
"totalPages": 477,
"result": [{
"name": "john doe",
"dob": "1999-11-11"
},
{
"name": "john1 doe1",
"dob": "1989-12-12"
}
]
}
Now I want to call this API n times, here n is equal to totalPages, after calling each API I want to write response result to the excel files.
First write page 1 response result to excel then append page 2 response result to excel file and so on..
I have written some sample code given below
function callAPI(pageNo) {
var options = {
url: "http://example.com/getData?pageNo="+pageNo,
method: 'GET',
headers: {
'Content-Type': 'application/json'
},
json: true
}
return request(options)
}
callAPI(1).then(function (res) {
// Write res.result to excel file
}).catch(function (err) {
// Handle error here
})
But facing problem calling recursively API and maintaining sequentially like write page 1 result first to excel file then page 2 result append to excel and so on..
Any code sample how to achieve in nodejs

You want to do something like this:
function getAllPages() {
function getNextPage(pageNo) {
return callAPI(pageNo).then(response => {
let needNextPage = true;
if (pageNo === 1) {
// write to file
} else {
// append to file
}
if (needNextPage) {
return getNextPage(pageNo+1);
} else {
return undefined;
}
});
}
return getNextPage(1);
}
Obviously change that 'needNextPage' to false to stop the recursion when you're done

So you want to do 477 requests in sequence? How long do you wanna wait for this to finish? Even in paralell, this would be still too long for me.
Best: write an API that can return you a batch of pages at once. Reducing the number of requests to the backend. Maybe something like http://example.com/getData?pages=1-100 and let it return an Array; maybe like
[
{
"totalRecords": 9524,
"currentPage": 1,
"totalPages": 477,
"result": [...]
},
{
"totalRecords": 9524,
"currentPage": 2,
"totalPages": 477,
"result": [...]
},
...
]
or more compact
{
"totalRecords": 9524,
"totalPages": 477,
"pages": [
{
"currentPage": 1,
"result": [...]
},
{
"currentPage": 2,
"result": [...]
},
...
]
}
Sidenote: writing the size of the results array into the json is unnecessary. This value can easily be determined from data.result.length
But back to your question
Imo. all you want to run in sequence is adding the pages to the sheet. The requests can be done in paralell. That already saves you a lot of overall runtime for the whole task.
callApi(1).then(firstPage => {
let {currentPage, totalPages} = firstPage;
//`previous` ensures that the Promises resolve in sequence,
//even if some later request finish sooner that earlier ones.
let previous = Promise.resolve(firstPage).then(writePageToExcel);
while(++currentPage <= totalPages){
//make the next request in paralell
let p = callApi(currentPage);
//execute `writePageToExcel` in sequence
//as soon as all previous ones have finished
previous = previous.then(() => p.then(writePageToExcel));
}
return previous;
})
.then(() => console.log("work done"));
or you wait for all pages to be loaded, before you write them to excel
callApi(1).then(firstPage => {
let {currentPage, totalPages} = firstPage;
let promises = [firstPage];
while(++currentPage < totalPages)
promises.push(callApi(currentPage));
//wait for all requests to finish
return Promise.all(promises);
})
//write all pages to excel
.then(writePagesToExcel)
.then(() => console.log("work done"));
or you could batch the requests
callApi(1).then(firstPage => {
const batchSize = 16;
let {currentPage, totalPages} = firstPage;
return Promise.resolve([ firstPage ])
.then(writePagesToExcel)
.then(function nextBatch(){
if(currentPage > totalPages) return;
//load a batch of pages in paralell
let batch = [];
for(let i=0; i<batchSize && ++currentPage <= totalPages; ++i){
batch[i] = callApi(currentPage);
}
//when the batch is done ...
return Promise.all(batch)
//... write it to the excel sheet ...
.then(writePagesToExcel)
//... and process the next batch
.then(nextBatch);
});
})
.then(() => console.log("work done"));
But don't forget to add the error handling. Since I'm not sure how you'd want to handle errors with the approaches I've posted, I didn't include the error-handling here.
Edit:
can u pls modify batch requests, getting some error, where you are assigning toalPages it's not right why the totalPages should equal to firstPage
let {currentPage, totalPages} = firstPage;
//is just a shorthand for
let currentPage = firstPage.currentPage, totalPages = firstPage.totalPages;
//what JS version are you targeting?
This first request, callApi(1).then(firstPage => ...) is primarily to determine currentIndex and totalLength, as you provide these properties in the returned JSON. Now that I know these two, I can initiate as many requests in paralell, as I'd want to. And I don't have to wait for any one of them to finish to determine at what index I am, and wether there are more pages to load.
and why you are writing return Promise.resolve([ firstPage ])
To save me some trouble and checking, as I don't know anything about how you'd implement writePagesToExcel.
I return Promise.resolve(...) so I can do .then(writePagesToExcel). This solves me two problems:
I don't have to care wether writePagesToExcel returns sync or a promise and I can always follow up with another .then(...)
I don't need to care wether writePagesToExcel may throw. In case of any Error, it all ends up in the Promise chain, and can be taken care of there.
So ultimately I safe myself a few checks, by simply wrapping firstPage back up in a Promise and continue with .then(...). Considering the amounts of data you're processing here, imo. this ain't too much of an overhead to get rid of some potential pitfalls.
why you are passing array like in resolve
To stay consistent in each example. In this example, I named the function that processes the data writePagesToExcel (plural) wich should indicate that it deals with multiple pages (an array of them); I thought that this would be clear in that context.
Since I still need this seperate call at the beginning to get firstPage, and I didn't want to complicate the logic in nextBatch just to concat this first page with the first batch, I treat [firstPage] as a seperate "batch", write it to excel and continue with nextBatch

function callAPI(pageNo) {
var options = {
url: "http://example.com/getData?pageNo="+pageNo,
method: 'GET',
headers: {
'Content-Type': 'application/json'
},
json: true
}
return request(options)
}
function writeToExcel(res){console.log(res)} //returns promise.
callAPI(1).then(function (res) {
if(res){
writeToExcel(res).then(() => {
var emptyPromise = new Promise(res => setTimeout(res, 0));
while(res && res.currentPage < res.totalPages){
emptyPromise = emptyPromise.then(() => {
return callAPI(res.currentPage).then(function (res){
if(res){
writeToExcel(res)
}
});
}
}
return emptyPromise;
});
}
}).catch(function (err) {
// Handle error here
})