How can I Promisify Node's mongodb module for cursors and/or a collections' toArray() using Bluebird?

Question

Relevant packages:

"dependencies": {
  "mongodb":    "1.4.x",
  "bluebird":   "2.3.x"
}

I've looked at:

How can I promisify the MongoDB native Javascript driver using bluebird?
Bluebird Promisfy.each, with for-loops and if-statements?
https://stackoverflow.com/a/21733446/438992
Bluebird's promisification docs
A few other places

I'm stuck after the findAsync({}).

I'd prefer a cursor, but it's rare I'd have too much to call toArray().

It's also possible I'm doing this completely wrong.

MongoClient.connectAsync('mongodb://127.0.0.1:27017/sr')
  .then(function(_db) {
    db = _db;
    return db.collectionAsync('posts');
  })
  .then(function(colPosts) {
    return colPosts.findAsync({});
  })
  .then ( A MIRACLE OCCURS )
  .catch(function(e) {
    console.log(e);
  })
  .finally(function() {
    if (db) db.close();
  });

Where the miracle occurs I want to either iterate over the cursor results or the arrayified collection. I'm having problems figuring out how to go about this.

Iterate over them, and do what? Where should the results go to? — Bergi, Aug 14 '14 at 12:17
check out http://stackoverflow.com/questions/24870812/promisify-cursor-execution-mongodb-native-driver — cubbuk, May 24 '16 at 14:48

kurttheviking · Answer 1 · 2014-09-06T07:36:02.320

As I understand it, .findAsync returns a promise for a cursor. If you want to pull the data into memory (as with .toArray) I think what you're looking for is something like:

MongoClient.connectAsync('mongodb://127.0.0.1:27017/sr')
  .then(function(_db) {
    db = _db;

    return db
      .collection('posts')
      .find({})
      .limit(limit)
      .sort(sort)
      .toArrayAsync();
  })
  .then(function(posts) {
    console.log('posts', posts);
  })
  .catch(function(e) {
    console.log(e);
  });

How can I Promisify Node's mongodb module for cursors and/or a collections' toArray() using Bluebird?

1 Answers1