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web3js Batch Request response doesn't have any context

I am sending batch requests to a moralis avalanche node which (half the time) returns token prices, but it only returns prices to the callback, I can't see the token addresses or anything related to the request I sent. Is there anyway to have some context sent to the callback? Or maybe a better way to send batch requests?
here is the callback:
const callbackMethod = (error, result) => {
if (error) {
console.log("error");
} else {
result.map((res) => {
console.log(res.toString())
})
}
}
and the requests:
const generateBatch = () => {
var batch = new web3.BatchRequest();
for (let i = 0; i < tokens.length; i++) {
for (let j = 0; j < tokens.length; j++) {
if (i != j) {
batch.add(contract.methods
.function(params)
.call.request({from: web3.eth.accounts.wallet.accounts["0"].address}, callbackMethod));
}
}
}
return batch;
}

My implementation was to write a wrapper around the function I was using (I was already going to deploy a contract for this project) and make it return both the prices and the path.

How to prevent received data from being messy by using promises and then() inside for loop [duplicate]

This question already has answers here:
Using async/await with a forEach loop
(33 answers)
Closed 4 years ago.
How can i manage to run this :
for(let i=0; i<3; i++){
setTimeout(function() {console.log("A")}, 500);
}
console.log('B');
and make it synchronous to get the following output :
AAAB
I oversimplified the situation here, but in my code, I have a for loop that iterates 3 times. Inside it, I first make an external API request which body's returned using a promise. I use then(). to run the suite of the loop's content.
BUT after the loop, I want to refresh the page.
The issue is that the page refreshes before the loop has finished :
// API call
function call(src,dest) {
return new Promise(function (resolve,reject) {
request('https://api.skypicker.com/flights?flyFrom='+src+'&to='+dest+'&dateFrom='+date+'&dateTo='+nextDate+'&partner=picky', function (err, res, body) {
if (!err && res.statusCode === 200) {
resolve(body);
} else {
reject(err);
}
});
})
}
Here is the for loop:
if (arr.length > 0 && arr[0]!==""){
for (let k = 0; k < arr.length ; k++){
let flight = call(dataPays.pays,arr[k]);
flight.then(function (result) {
info.dest = result;
}).catch(function (error) {
console.log("ERROR :" + error );
}).then(function () {
let object = JSON.parse(info.dest);
let myArray = object.data;
dataPays.dest[count]=dataPays.pays + " --> " + arr[k]+ ": ";
count++;
//start
for (let j = 0; j < myArray.length ; j++){
if (!valueExists(checker,object.data[j]["flyTo"])){
let string = "dest_" + j;
dataPays.dest[count]=" from "+object.data[j]["flyFrom"] + " to " +object.data[j]["flyTo"] + " " + object.data[j]["price"]+ "€ " ;
checker[string] = object.data[j]["flyTo"];
count++;
}
}
}).then(function () {
console.log("after then " + k + " -- " );
if (k === arr.length-1){
console.log("refreshing");
res.redirect(req.get('referer'));
}
})
}
}
Here, We can see that I've tried to fix the issue by using the value of k to refresh the page at the last iteration of the loop. However, The console.log(k) shows that its value is kind of random. The loop is not waiting for the previous iteration to finish before running again.
I also tried to put the redirect part outside the for loop but it doesn't work either.
My guess is that I should use a callback, But I have no idea how to do it in this code.

Put all your promises in an array and use Promise.all();
Simplified example:
let promises = [];
for (let i=0; i<3; i++) {
promises.push(methodThatReturnsPromise());
}
return Promise.all(promises).then((results) => {
console.log('This will reliably execute after all promises, results are:', results);
})
Note that results is an array with results of respective promises, following the order of the promises in the input array.

How can I execute a statement AFTER a loop finishes in javascript?

I'm querying a mongo database to retrieve the tiles for the display in rougelike game. This is the function I use:
function get_display(){
var collections = ['austinsroom'];
var db = mongojs(uri, collections);
var temphtml = '';
for(var j = 0; j < 3; j++) {
console.log("y=" + String(j));
db.austinsroom.find({"y": j}, {}).sort({"x": 1}, function(err, records) {
if(err) {
console.log("There was an error executing the database query.");
return;
}
var i = records.length;
while(i--) {
temphtml += records[i].display;
}
temphtml += '<br>';
//console.log(temphtml);
//return temphtml;
//THE ONLY WAY I CAN GET ANYTHING TO PRINT IN THE CONSOLE IS IF I PUT IT INSIDE THE LOOP HERE
});
//console.log(temphtml);
//return temphtml;
//THIS DOES NOTHING
}
//console.log(temphtml);
//return temphtml;
//THIS DOES NOTHING
}
get_display();
If I put the console.log(temphtml) inside the loop, it prints out three times which isn't what I want. I only want the final string (i.e. ...<br>...<br>...<br>. Also I can't ultimately return the temphtml string, which is actually the important thing. Is this some quirk of javascript? Why would it not execute statements after the loop?
Also: is there a better way to retrieve every element of a grid that's stored in a mongo database, in order, so it can be displayed properly? Here's what the mongo documents look like:
{
"_id": {"$oid": "570a8ab0e4b050965a586957"},
"x": 0,
"y": 0,
"display": "."
}
Right now, the game is supposed to display a "." in all empty spaces using the x and y values for the coordinates. The database is indexed by "x" values.

See async.whilst. You want flow control of the for loop, for which this provides a callback to control each loop iteration.
var temphtml = "",
j = 0;
async.whilst(
function() { return j < 3 },
function(callback) {
db.austinsroom.find({"y": j }, {}).sort({"x": 1}, function(err, records)
temphtml += records.map(function(el) {
return el.display;
}).join("") + '<br>';
j++;
callback(err);
});
},
function(err) {
if (err) throw err;
console.log(temphtml);
}
)
Either that or use Promise.all() on collected promises to return "one big result". But you would also need to switch to promised-mongo from mongojs, as the nearest equivalent, since there are more mongodb drivers that actually support promises. That one is just the direct fork from mongojs:
var temphtml = "",
j = 0,
promises = [];
for ( var j=0; j < 3; j++ ) {
promises.push(db.austinsroom.find({"y": j }, {}).sort({"x": 1}).toArray());
promises.push('<br>'); // this will just join in the output
)
Promise.all(promises).then(function(records) {
temphtml += records.map(function(el) {
return el.display;
}).join("");
})
Not exactly the same thing, since it's one list output and not three, but the point is that the Promise objects defer until actually called to resolve, so you can feed the paramters in the loop, but execute later.

I do not use MongoDB but from what I am reading it is asynchronous. So what is happening is your db.austinsroom.find call fires another "thread" and returns to the for loop to continue the next iteration.
One way to do what you want is have a check at the end of your db.austinsroom.find function to see if you're done with the for loop. Something like:
function get_display()
{
var collections = ['austinsroom'];
var db = mongojs(uri, collections);
var temphtml = '';
var doneCounter = 0;
for(var j = 0; j < 3; j++)
{
console.log("y = " + String(j));
db.austinsroom.find({"y": j}, {}).sort({"x": 1}, function(err, records)
{
if(err)
{
console.log("There was an error executing the database query.");
return;
}
var i = records.length;
while(i--)
{
temphtml += records[i].display;
}
temphtml += '<br>';
// we're done with this find so add to the done counter
doneCounter++;
// at the end, check if the for loop is done
if(doneCounter == 3)
{
// done with all three DB calls
console.log(temphtml);
}
});
}
}
This is probably not the best way as I know nothing about MongoDB but it should put you on the right path.

Where to put the callback?

db.listCollections().toArray(function(err, collections){
for(i = 1; i < collections.length; i++){
if(i < parseInt(collections.length)){
var collect = db.collection(collections[i].name.toString(),function(){
collect.count(function(err,result){
console.log(collections[i].name.toString());
corrCount = corrCount + result;
});
});
}else{
collect = collections[i].name;
}
}
});
So my problem is that collect ends up being undefined and thus one can't count the amount of entries in the collection. Something tells me that I should solve this with callback but I keep failing. Also I don't understand why the console prints out 2 times before it shots of the error. I'm using nodejs with mongodb native driver.

You need to move the rest of the code out of the callback, like so:
db.listCollections().toArray(function(err, collections) {
for (i = 1; i < collections.length; i++) {
if (i < parseInt(collections.length)) {
var collect = db.collection(collections[i].name.toString());
collect.count(function(err, result) {
console.log(collections[i].name.toString());
corrCount = corrCount + result;
});
} else {
collect = collections[i].name;
}
}
});

Looping through x after all i : node.js

I have this code. I want to loop through all Users in a database and for each user get a list of their Portfolios (which in turn is a collection of stocks):
calculatePortfolios: function(callback) {
var thisuser;
module.exports.getAllUsers(function(err, users) {
/* Loop through all users with i */
for(var i = 0; i < users.length; i++) {
console.log('i = ' + i);
console.log(users.length);
thisuser = users[i]; // Store current user.
/* Loop through all held stocks in current user's portfolio. */
module.exports.getPortfolio(thisuser.username, function(err, portfolio) {
for(var x = 0; x < portfolio.length; x++) {
console.log('x = ' + x);
var total = parseFloat((portfolio[x].held * portfolio[x].unitprice) + thisuser.cash);
console.log(total);
console.log(thisuser.username);
module.exports.updateInvestor(thisuser.username, total, function(err, result) {
console.log(thisuser.username + ' ' + total);
});
}
});
}
callback(err, 'OK');
});
},
The result I get is that all i indices (users) are looped through before all x indices (portfolios). Shouldn't x be an inner loop of i?
Is this something related to how Node.JS works?
Any help is much appreciated. Thank you.

the getPortfolio() is most likely an asynchronous operation, and depending on the internal implementation it may either queue the calls or translate them to http requests for example that may take time, when these requests are completed only then your callback function that operates with x will be called.
But meanwhile getPortfoli() call will return. That is exactly why you see it iterating fast over all your i's, and only then you callback starts getting called.

Lack of JOIN's is really confusing to users who come with SQL background to node.js (event-driven) and NoSQL databases.
Consider this flow for your task:
Load all users.
Iterate through each user and record field which is used for collection relationship (username in your case), usually it is _id.
2b. (Optional) make Object, where key - will be field of relationship, in your case username, and value - will be object it self.
Make another query to related collection with similar query: { _id: { $in: ids } } where ids will be array of user _id's. In your case you need list of usernames.
Iterate through each portfolio item and add it to user object. If 2b did - then no need of two iterations.
Users are done, and have portfolio data and ready to be used.

#PSL: Got it working with async.waterfall. Probably not the most elegant solution, but it works for now.
/**
* #description Calculate the value of an investor's portfolio.
* #function
*/
calculatePortfolios: function(callback) {
async.waterfall([
function(callback) {
var allUsers = [];
module.exports.getAllUsers(function(err, users) {
for(var i = 0; i < users.length; i++) {
allUsers.push(users[i]);
}
});
callback(null, allUsers);
},
function(allUsers, callback) {
var totals = [];
for(var i = 0; i < allUsers.length; i++) {
module.exports.getPortfolio(allUsers[i].username, function(err, portfolio) {
for(var x = 0; x < portfolio.length; x++) {
totals.push(parseFloat(portfolio[x].held * portfolio[x].unitprice));
}
});
}
callback(null, allUsers, totals);
},
function(allUsers, totals, callback) {
for(var i = 0; i < allUsers.length; i++) {
module.exports.updateInvestor
(allUsers[i].username, (totals[i] + allUsers[i].cash), function(err, result) {
console.log('Updated an investor!');
});
}
callback(null, 'OK');
}
]);
callback(null, 'OK');
},