How to use mongoose findOne


Question

I have the below schema (apologies that it is in coffeescript)

Schema = mongoose.Schema

AuthS = new Schema
    auth:   {type: String, unique: true}
    nick:   String
    time:   Date
Auth = mongoose.model 'Auth', AuthS

I simply want to recover one record which is definitely in my database:

Auth.findOne({nick: 'noname'}, function(obj) { console.log(obj); });

Unfortunately this always logs null. db.auths.findOne({nick: 'noname'}) in mongo shell always returns a value. What is going on?

1
38
8/12/2011 1:29:52 PM

Accepted Answer

Found the problem, need to use function(err,obj) instead:

Auth.findOne({nick: 'noname'}, function(err,obj) { console.log(obj); });
81
8/11/2011 10:20:33 PM

Mongoose basically wraps mongodb's api to give you a pseudo relational db api so queries are not going to be exactly like mongodb queries. Mongoose findOne query returns a query object, not a document. You can either use a callback as the solution suggests or as of v4+ findOne returns a thenable so you can use .then or await/async to retrieve the document.

// thenables
Auth.findOne({nick: 'noname'}).then(err, result) {console.log(result)};
Auth.findOne({nick: 'noname'}).then(function (doc) {console.log(doc)});

// To use a full fledge promise you will need to use .exec()
var auth = Auth.findOne({nick: 'noname'}).exec();
auth.then(function (doc) {console.log(doc)});

// async/await
async function auth() {
  const doc = await Auth.findOne({nick: 'noname'}).exec();
  return doc;
}
auth();

See the docs if you would like to use a third party promise library.


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