Nullable attributes

You can change the way an attribute is treated when the value null is assigned to it by using the nullable option with the value true, this would affect the way the attribute is coerced, validated and serialized.

If you do not set the nullable option for an attribute it will default to false and make your attribute not nullable.

/*
 * User.js
*/
const User = attributes({
  name: {
    type: String,
    empty: true
  },
  age: Number,
  active: Boolean,
  createdAt: Date
})(class User { });

const user = new User({
  name: null,
  age: null,
  active: null,
  createdAt: null
});

user.attributes; // { name: '', age: 0, active: false, createdAt: 1970-01-01T00:00:00.000Z }
user.validate() // { valid: true }

Nullable optional attributes

When you set an optional attribute to be nullable you are choosing not to assign a default value for it when instantiating your structure passing null as the value of this attribute, so the actual value will be null and will be considered valid.

/*
 * User.js
*/
const User = attributes({
  name: {
    type: String,
    nullable: true
  }
})(class User { });

const user = new User({
  name: null
});

user.attributes; // { name: null }
user.validate() // { valid: true }

Nullable required attributes

We consider that when an attribute is required there should be some value assigned to it even if it's undefined, null or any other value. It means that coercion will never assign a default value to required attributes even if nullable option is false.

/*
 * User.js
*/
const User = attributes({
  name: {
    type: String,
    required: true,
    nullable: false // non-nullable required attribute
  }
})(class User { });

const user = new User({
  name: null
});

user.attributes; // { name: null }
user.validate() // { valid: false }

But notice that you can choose to allow null values on required attributes which will cause the validation to return true.

/*
 * User.js
*/
const User = attributes({
  name: {
    type: String,
    required: true,
    nullable: true
  }
})(class User { });

const user = new User({
  name: null
});

user.attributes; // { name: null }
user.validate() // { valid: true }

Important:

• Notice that by not using the nullable option the default value for String is an empty string, which means that you need to accept empty strings to make your schema valid.

• Notice that usually an attribute with the value undefined or null is not included when you serialize your structure, but when it is nullable this attribute is going to be returned in your serialized schema.