Can I add non-persistent fields to a model?

Question

Is there a recommended practice for adding non-persistent attributes to an Objection model object such that it that won't overwrite predefined attributes?

Answer 1

Objection models have the virtualAttributes field. From the documentation:

The virtual values are not written to database. Only the “external” JSON format will contain them.

It is important to note these are functions, not just model properties.

Example from the docs:

class Person extends Model {
  static get virtualAttributes() {
    return ['fullName', 'isFemale'];
  }

  fullName() {
    return `${this.firstName} ${this.lastName}`;
  }

  get isFemale() {
    return this.gender === 'female';
  }
}

const person = Person.fromJson({
  firstName: 'Jennifer',
  lastName: 'Aniston',
  gender: 'female'
});

console.log(person.toJSON());
// --> {"firstName": "Jennifer", "lastName": "Aniston", "isFemale": true, "fullName": "Jennifer Aniston"}