After saving an object using mongoose, what is the simplest way I can return an object with a subset of fields?

You may add a method, getPublicFields which returns an object containing strictly the public fields.

orgSchema.methods.getPublicFields = function () {    var returnObject = {        name: this.name,        address: this.address,        randomField: this.randomField    };    return returnObject;};

You may also add a callback to that function and perform some other queries to aggregate data, if you wish to do that. After the method is complete, just call

var orgPublic = org.getPublicFields();

If anyone is still interested in a more mongoose friendly answer see the following.

When you use .select(...) you can see that the mongoose doc still has all its fields and the _doc property is the one to be reduce.

What you can do is after saving a new doc remove the fields you want out of newDoc['_doc'].

Now you are able to use the newDoc.toObject() to pull the "public" fields you specified.

In the example below I'm using _.pick() to create a white list the fields I want, but you can use _.remove() to create a black list as well.

Note that the publicFiledsarray can be use in the .select(...) for querying so you only need one publicFileds definition for your CRUD actions.

var MyModel = require('./MyModel');var _ = require('lodash');var publicFileds = ['_id', 'name', 'age'];function create(newModelData, cb) {    var newModle = new MyModel(newModelData);    newModle.save(function (err, newDoc) {        if (err) {            cb(err);            return;        }        newDoc['_doc'] = _.pick(newDoc['_doc'], publicFileds);        cb(null, newDoc);    }}