set field as empty for mongo object using mongoose

Question

I'm calling user.save() on an object, where I set user.signup_date = null;

user.first_name = null;
user.signup_date = null;

user.save();

But when I look at the user in the mongodb it still has the signup_date and first_name set...how do I effectively set this field as empty or null?

JohnnyHK · Accepted Answer · 2020-04-12T15:15:28.953

51

To remove those properties from your existing doc, set them to undefined instead of null before saving the doc:

user.first_name = undefined;
user.signup_date = undefined;

user.save();

Confirmed as still working in Mongoose 5.9.7. Note that the field you're trying to remove must still be defined in your schema for this to work.

edited Apr 12 '20 at 15:15

answered Sep 28 '12 at 12:31

JohnnyHK

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Very nice answer save a lot of my time :) – Sudhanshu Gaur Jun 02 '16 at 16:12
What about if filed is an Array it is not wokring :( – Anil Yadav Jun 30 '17 at 08:59
@AnilYadav Array fields are handled specially by Mongoose and should always exist (but can be empty, of course). – JohnnyHK Jun 30 '17 at 14:58
IS this still a valid answer? I am using mongoose 5.5.11, mongo 3.6 and setting the field as undefined does not remove the field, it sets it to null – faniva Jan 15 '20 at 19:01
@faniva Yes, I just confirmed it's still working in 5.9.7. Note that the field you're trying to remove must still be defined in your schema. – JohnnyHK Apr 12 '20 at 15:17

score 4 · Answer 2 · answered Sep 28 '12 at 09:33

Does it make a difference if you try the set method instead, like this:

user.set('first_name', null);
user.set('signup_date', null);
user.save();

Or maybe there's an error when saving, what happens if you do:

user.save(function (err) {
    if (err) console.log(err);
});

Does it print anything to the log?

score 4 · Answer 3 · answered Mar 21 '18 at 15:35

4

Another option is to define a default value as undefined for these properties.

Something like the following:

let userSchema = new mongoose.Schema({ first_name: { type: String, default: undefined }, signup_date: { type: Date, default: undefined } })

answered Mar 21 '18 at 15:35

Kfir Erez

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Necessary only on type:Array and type:Map, but great tip !! – gugabguerra Oct 26 '20 at 01:18

score 1 · Answer 4 · answered Sep 28 '12 at 15:20

1

Just delete fields

delete user.first_name;
delete user.signup_date;
user.save();

answered Sep 28 '12 at 15:20

PierrickP

97
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2

You could try this after doing: `user = user.toObject()` first. – k00k May 06 '13 at 15:53

score 1 · Answer 5 · answered Mar 14 '19 at 10:47

On Mongoose documentation (Schema Types), you can go to the Arrays explanation. There, it says this:

Arrays are special because they implicitly have a default value of [] (empty array).

var ToyBox = mongoose.model('ToyBox', ToyBoxSchema);
console.log((new ToyBox()).toys); // []

To overwrite this default, you need to set the default value to undefined

(I've made an addition inside the toys element)

var ToyBoxSchema = new Schema({
     toys: {
          type: [{
              name: String,
              features: [String]
          }],
          default: undefined
     }
});

set field as empty for mongo object using mongoose

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