getting random n record not wroking

Question

function get() {
    return new Promise(function (resolve, reject) {

        Card.find([
            { $sample: {size: 3} }, 
            { $match:  {"deckId": req.body.deckId} }
        ]).exec(function(err,result){
            if(err){
                reject(err);
            }else{
                resolve(result)
            }
        });

    });
}

It gives me all data but i need only 3 random data. i have google about get random N no of data but why not working for me?

Try using `aggregate` instead of `find` here and have a look at a very similar case [here](https://stackoverflow.com/questions/24806721/mongodb-how-to-find-10-random-document-in-a-collection-of-100). — vahdet, Jul 12 '18 at 10:52
deckId: { type: Schema.Types.ObjectId, ref: 'Decks', required: 'Please Provide Deck' } My deckId schema — Devendra Chauhan, Jul 12 '18 at 10:58
new mongoose.Types.ObjectId(req.body.deckId) solve my problem — Devendra Chauhan, Jul 12 '18 at 11:06
Never mix callback and promise, you can simply `return Card.find(...).exec()` to return the promise. — kit, Jul 12 '18 at 11:17

score 0 · Answer 1 · answered Jul 12 '18 at 11:05

function get() {
    return new Promise(function (resolve, reject) {

        Card.aggregate([
            { $sample: {size: Number(req.body.wordCount)} }, 
            { $match:  {"deckId": new mongoose.Types.ObjectId(req.body.deckId)} }
        ]).exec(function(err,result){
            if(err){
                reject(err);
            }else{
                resolve(result)
            }
        });

    });
}

getting random n record not wroking

1 Answers1