Can't use "delete" operator on mongoose query results

Question

I'm trying to delete a key before sending data back to the browser. For some reason, maybe because it is a mongoose object, this isn't working:

delete myObject.property

If I do console.log(delete myObject.property) I get true which I understand means the property was not deleted. How can I get rid of this key?

(More background: I know I could leave it off by using a mongoose select query, but I do need to select the key initially. I can also set it to null, which works fine, but I'd much rather get rid of the key completely)

Answer 1

As MikaS states, you need to convert to convert the Mongoose document object into an ordinary object first:

const newObj = myObject.toObject();
delete newObj.property;

This should be fine if you're doing this once. However, if you have to repeat this logic everywhere you return this this type of document with certain keys omitted or other transformations, you should define transformations on your schema:

// specify the transform schema option
if (!schema.options.toObject) schema.options.toObject = {};
schema.options.toObject.transform = function (doc, ret, options) {
  // any kind of simple/complicated transformation logic here
  // remove the _id of every document before returning the result
  delete ret._id;
  return ret;
}

// without the transformation in the schema
doc.toObject(); // { _id: 'anId', name: 'Wreck-it Ralph' }

// with the transformation
doc.toObject(); // { name: 'Wreck-it Ralph' }

Read about Document#toObject and transformations in the docs

Answer 2

Convert the Mongoose document object to an ordinary Javascript object first:

const newObj = myObject.toObject();
delete newObj.property;