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Array push only works inside the callback

0

I'm trying to update an array with some mongoose values. But it only works if the array.push is inside the callback function. I've tried to code in several ways but outside the callback I always get an empty array. Here are some code:

let y = [];

Shops.countDocuments( dt_encerramento: $gte: jan, $lte: abr )
 .then(function(os) 
 y.push(os);
 )
 .catch(err => throw err; );

 console.log(y);

Using async/await:

let y = [];

async function docs() 
 const numDocs = await Shops.countDocuments( dt_encerramento: $gte: jan, $lte: abr ).exec();
 return numDocs;


docs().then(function (err,n) y.push(n); );

console.log(y);

Help, please. I don't know what to do...

arrays node.js count array-push

share|improve this question

edited Mar 8 at 20:17

Luc

288

asked Mar 8 at 17:28

Fábio MedeirosFábio Medeiros

11

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Why in the first function you do not use the exec() method and the second one you used it?
  
  – SergioEscudero
  Mar 8 at 17:31
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Put the console.log() inside the callback function, on the line after you modify the array. Because it's async, the array has not yet been modified at the time you log it.
  
  – Martin Joiner
  Mar 8 at 17:33
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Thanks Sergio, I just forgot the exec(), but it doesn't alter the results.
  
  – Fábio Medeiros
  Mar 8 at 17:36
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Martin, thanks for your reply. Your suggestion works but I need the updated array outside the callback, how could I retrieve it?
  
  – Fábio Medeiros
  Mar 8 at 17:39
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @FábioMedeiros I would recommend you read up on the basic concepts of Asynchronous code. Basically you cannot assume the code executes in the order it is written so even though your console.log(y) is on the last line, it does not mean the push() has happened yet. I can recommend MDN as a source of learning developer.mozilla.org/en-US/docs/Learn/JavaScript/Asynchronous
  
  – Martin Joiner
  Mar 11 at 20:43
  

  
  
  
  

add a comment | 

0

I'm trying to update an array with some mongoose values. But it only works if the array.push is inside the callback function. I've tried to code in several ways but outside the callback I always get an empty array. Here are some code:

let y = [];

Shops.countDocuments( dt_encerramento: $gte: jan, $lte: abr )
 .then(function(os) 
 y.push(os);
 )
 .catch(err => throw err; );

 console.log(y);

Using async/await:

let y = [];

async function docs() 
 const numDocs = await Shops.countDocuments( dt_encerramento: $gte: jan, $lte: abr ).exec();
 return numDocs;


docs().then(function (err,n) y.push(n); );

console.log(y);

Help, please. I don't know what to do...

arrays node.js count array-push

share|improve this question

edited Mar 8 at 20:17

Luc

288

asked Mar 8 at 17:28

Fábio MedeirosFábio Medeiros

11

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Why in the first function you do not use the exec() method and the second one you used it?
  
  – SergioEscudero
  Mar 8 at 17:31
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Put the console.log() inside the callback function, on the line after you modify the array. Because it's async, the array has not yet been modified at the time you log it.
  
  – Martin Joiner
  Mar 8 at 17:33
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Thanks Sergio, I just forgot the exec(), but it doesn't alter the results.
  
  – Fábio Medeiros
  Mar 8 at 17:36
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Martin, thanks for your reply. Your suggestion works but I need the updated array outside the callback, how could I retrieve it?
  
  – Fábio Medeiros
  Mar 8 at 17:39
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @FábioMedeiros I would recommend you read up on the basic concepts of Asynchronous code. Basically you cannot assume the code executes in the order it is written so even though your console.log(y) is on the last line, it does not mean the push() has happened yet. I can recommend MDN as a source of learning developer.mozilla.org/en-US/docs/Learn/JavaScript/Asynchronous
  
  – Martin Joiner
  Mar 11 at 20:43
  

  
  
  
  

add a comment | 

I'm trying to update an array with some mongoose values. But it only works if the array.push is inside the callback function. I've tried to code in several ways but outside the callback I always get an empty array. Here are some code:

let y = [];

Shops.countDocuments( dt_encerramento: $gte: jan, $lte: abr )
 .then(function(os) 
 y.push(os);
 )
 .catch(err => throw err; );

 console.log(y);

Using async/await:

let y = [];

async function docs() 
 const numDocs = await Shops.countDocuments( dt_encerramento: $gte: jan, $lte: abr ).exec();
 return numDocs;


docs().then(function (err,n) y.push(n); );

console.log(y);

Help, please. I don't know what to do...

arrays node.js count array-push

share|improve this question

edited Mar 8 at 20:17

Luc

288

asked Mar 8 at 17:28

Fábio MedeirosFábio Medeiros

11

let y = [];

Shops.countDocuments( dt_encerramento: $gte: jan, $lte: abr )
 .then(function(os) 
 y.push(os);
 )
 .catch(err => throw err; );

 console.log(y);

let y = [];

async function docs() 
 const numDocs = await Shops.countDocuments( dt_encerramento: $gte: jan, $lte: abr ).exec();
 return numDocs;


docs().then(function (err,n) y.push(n); );

console.log(y);

share|improve this question

edited Mar 8 at 20:17

Luc

288

asked Mar 8 at 17:28

Fábio MedeirosFábio Medeiros

11

share|improve this question

edited Mar 8 at 20:17

Luc

288

asked Mar 8 at 17:28

Fábio MedeirosFábio Medeiros

11

edited Mar 8 at 20:17

Luc

288

edited Mar 8 at 20:17

Luc

288

asked Mar 8 at 17:28

Fábio MedeirosFábio Medeiros

11

asked Mar 8 at 17:28

Fábio MedeirosFábio Medeiros

11

1 Answer
1

active

oldest

votes

0

My understanding is that you are missing a promise.

let y = [];

const docs = async () => 
 return await Promise.all(Shops.countDocuments( dt_encerramento: $gte: jan, $lte: abr ).exec());


const docsToPush = docs()
y.push(docsToPush)
console.log(y);

share|improve this answer

answered Mar 8 at 18:27

LucLuc

288

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @FábioMedeiros Just an extra note, I'm making the assumption you are using this to build a web app or api of some sort, you could change the const to var but I would recommend against this, using var opens you up to possible security threats.
  
  – Luc
  Mar 8 at 20:25
  

  
  
  
  

add a comment | 

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0

My understanding is that you are missing a promise.

let y = [];

const docs = async () => 
 return await Promise.all(Shops.countDocuments( dt_encerramento: $gte: jan, $lte: abr ).exec());


const docsToPush = docs()
y.push(docsToPush)
console.log(y);

share|improve this answer

answered Mar 8 at 18:27

LucLuc

288

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @FábioMedeiros Just an extra note, I'm making the assumption you are using this to build a web app or api of some sort, you could change the const to var but I would recommend against this, using var opens you up to possible security threats.
  
  – Luc
  Mar 8 at 20:25
  

  
  
  
  

add a comment | 

0

My understanding is that you are missing a promise.

let y = [];

const docs = async () => 
 return await Promise.all(Shops.countDocuments( dt_encerramento: $gte: jan, $lte: abr ).exec());


const docsToPush = docs()
y.push(docsToPush)
console.log(y);

share|improve this answer

answered Mar 8 at 18:27

LucLuc

288

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @FábioMedeiros Just an extra note, I'm making the assumption you are using this to build a web app or api of some sort, you could change the const to var but I would recommend against this, using var opens you up to possible security threats.
  
  – Luc
  Mar 8 at 20:25
  

  
  
  
  

add a comment | 

My understanding is that you are missing a promise.

let y = [];

const docs = async () => 
 return await Promise.all(Shops.countDocuments( dt_encerramento: $gte: jan, $lte: abr ).exec());


const docsToPush = docs()
y.push(docsToPush)
console.log(y);

share|improve this answer

answered Mar 8 at 18:27

LucLuc

288

let y = [];

const docs = async () => 
 return await Promise.all(Shops.countDocuments( dt_encerramento: $gte: jan, $lte: abr ).exec());


const docsToPush = docs()
y.push(docsToPush)
console.log(y);

share|improve this answer

answered Mar 8 at 18:27

LucLuc

288

answered Mar 8 at 18:27

LucLuc

288

answered Mar 8 at 18:27

LucLuc

288