async save multiple document with mongoose

Question

i am updating 2 documents using mongoose.save(), but i think the way I am doing is is not safe, as far as i know i need to use async to make sure all documents are being executed

// array containing the 2 documents from db 
let schedules 
let newItem = {
   isActive: room.isActive,
   name: room.roomname
};

// adding new items to nested array
schedules[0].rooms.push(newItem);
schedules[1].rooms.push(newItem);

// saving / updating documents 


var total = schedules.length,
  result = [];

function saveAll() {
  var doc = schedules.pop();

  doc.save(function(err, saved) {
    if (err) throw err; //handle error

    result.push(saved);

    if (--total) saveAll();
    else {
      // all saved here
      res.json(result);
    }
  });
}

saveAll();

any explanation how to do it correctly

deerawan · Accepted Answer · 2018-08-16 08:13:21Z

4

We can use promise.all for this but we need to change your save function to promise based function

...

var total = schedules.length,
  result = [];

function saveAll() {
  const promises = schedules.map(schedule => save(schedule));
  return Promise.all(promises)
    .then(responses => {
      // all saved processes are finished
      res.json(responses);
    })
}

// convert callback `save` function to promise based
function save(doc) {
  return new Promise((resolve, reject) => {
    doc.save((err, saved) => {
      if (err) {
        reject(err);
      }

      resolve(saved);
    });
  });
}

If you can use async/await we can make saveAll function cleaner

async function saveAll() {
  const promises = schedules.map(schedule => save(schedule));
  const responses = await Promise.all(promises);

  res.json(responses);    
}

Hope it helps

answered Aug 16, 2018 at 8:13

deerawan

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1 Comment

dan-man Over a year ago

it might be a bad idea to use Promise.all( <array of mongo queries> ) because there is a finite pool of connections to mongo (I think default is 5), so this one command could swamp the pool for several hundred milliseconds (or whatever), blocking all other access to mongo from this process.

Abderrahim Soubai-Elidrisi · Accepted Answer · 2018-08-15 16:04:55Z

0

Use Promises :

doc1.save().exec().then(
    data => {

        doc1.save().exec().then(
            data2 => console.log(data2)
        ).catch(err2 => console.log(err2))
    }
).catch(err1 => console.log(err1))

answered Aug 15, 2018 at 16:04

Abderrahim Soubai-Elidrisi

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