Transform an array of documents using mongoose

Question

Transform an array of documents using mongoose

I am running a special query in which I want transform the results after.

User.find({}, function(err, users) {
  // I want to remove/add some properties from/to each user here
});

Is there a way to transform an array of documents? Also this is a special case so I do not want to apply a transformation to the Schema, which I think would transform each document like I want, but would also affect all other queries to the User model.

Basically I want the ability to perform a one time transformation on the array of docs returned.

User.find({}, function(err, users) {
  // I want to remove/add some properties to each user here
  users.toJSON({transform: function(doc,ret,options) { /* do tranform*/ });
  // That will not work as I get an error that toJSON is not defined for that
  // array that was returned.
});

I might be able to fake it out by adding a transformation right before I query and then removing that transformation when the query is complete, but that is a pretty bad hack IMHO.

Ideas? Did I miss something in the docs?

node.js
mongoose

Answer 1

You can use a lean query so that an array of plain JS objects are returned from the query and then use map to transform the array:

User.find({}).lean().exec(err, users) {
    users = users.map(function(user) {
        // transform user into newuser as needed.
        ...
        return newuser;
    });
});