Underscore's Cloning of Mongoose Objects and Deleting Properties Not Working?

Question

I'm using Mongoose and I want to remove the _id property from my Mongoose instance before I send the JSON response to the client.

Example:

var ui = _.clone(userInvite);
delete ui["_id"];
console.log(JSON.stringify(ui)); //still has "_id" property, why?

The previous didn't work.

However, if I do:

var ui = JSON.parse(JSON.stringify(userInvite)); //poor man's clone
delete ui["_id"];
console.log(JSON.stringify(ui)); //"_id" is gone! it works!

I don't understand why calling delete on a cloned object using Underscore doesn't work, but if I do the hacky JSON.string/JSON.parse, it works.

Any thoughts on this behavior?

Answer 1

I just came across a similar issue trying to replace _id with id. Doing this worked for me:

Schema.methods.toJSON = function(options) {
  var document = this.toObject(options);
  document.id = document._id.toHexString();
  delete(document._id);
  return document;
};

Maybe it will start working if you replace delete ui["_id"] with delete ui._id or use toObject instead of _.clone.

Answer 2

Just to add to the previous answer, there is one more way to achieve the same. 'toObject' function applies transformation to the document which is defined by the schema.options.toObject.transform function, e.g

schema.options.toObject.transform = function(doc, ret) {
    ret.id = doc._id;
    delete ret._id;
};