mongoose find by mail code example
Example 1: mongoose response to object
MyModel.findOne().lean().exec(function(err, doc) {
doc.addedProperty = 'foobar';
res.json(doc);
});
Example 2: callback mongoose get value from document
var query = Model.find({});
query.where('field', 5);
query.limit(5);
query.skip(100);
query.exec(function (err, docs) {
// called when the `query.complete` or `query.error` are called
// internally
});