CODEWITHSUNDEEP
node.jsmongoosemongoose-schema
Dushyant Bangal
Dushyant Bangal

Reputation: 6403

Mongoose accepts null for Number field

I have a mongoose schema where I'm storing a port number. I also have a default value set for the field.

port:{
    type:Number,
    default:1234
}

If I don't get any value via my API, it gets set to 1234. However, If someone sends null, it accepts null and saves to database.

Shouldn't it covert null to 1234? null is not a number! Am I understanding it wrong?

I am considering the solution given here, but I dont want to add extra code for something that should work without it (unless I'm wrong and its not supposed to convert null to 1234)

Upvotes: 5

Views: 10690

Answers (2)

Deeksha Sharma
Deeksha Sharma

Reputation: 3359

As explained in mongoose official docs here

Number To declare a path as a number, you may use either the Number global constructor or the string 'Number'.

const schema1 = new Schema({ age: Number }); // age will be cast to a Number
const schema2 = new Schema({ age: 'Number' }); // Equivalent

const Car = mongoose.model('Car', schema2);
There are several types of values that will be successfully cast to a Number.

new Car({ age: '15' }).age; // 15 as a Number
new Car({ age: true }).age; // 1 as a Number
new Car({ age: false }).age; // 0 as a Number
new Car({ age: { valueOf: () => 83 } }).age; // 83 as a Number

If you pass an object with a valueOf() function that returns a Number, Mongoose will call it and assign the returned value to the path.

The values null and undefined are not cast.

NaN, strings that cast to NaN, arrays, and objects that don't have a valueOf() function will all result in a CastError.

Upvotes: 0

rsp
rsp

Reputation: 111316

See the comments in this issue:

null is a valid value for a Date property, unless you specify required. Defaults only get set if the value is undefined, not if its falsy.

(it's about dates but it can be applied to numbers just as well.)

Your options are to either:

  • add required to the field
  • add a custom validator that would reject it
  • use hooks/middleware to fix the issue

You might get away with a pre-save or post-validate (or some other) hook like this:

YourCollection.pre('save', function (next) {
  if (this.port === null) {
    this.port = undefined;
  }
  next();
});

but probably you'll have to use something like:

YourCollection.pre('save', function (next) {
  if (this.port === null) {
    this.port = 1234; // get it from the schema object instead of hardcoding
  }
  next();
});

See also this answer for some tricks on how to make null trigger default values in function invocation:

This is unfortunate that Mongoose cannot be configured to tread null as undefined (with some "not-null" parameter or something like that) because it is sometimes the case that you work with data that you got in a request as JSON and it can sometimes convert undefined to null:

> JSON.parse(JSON.stringify([ undefined ]));
[ null ]

or even add null values where there was no (explicit) undefined:

> JSON.parse(JSON.stringify([ 1,,2 ]));
[ 1, null, 2 ]

Upvotes: 5

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