PersonModel.js

const { Model } = require('objection');
const Animal = require('./Animal');

class Person extends Model {
  // Table name is the only required property.
  static get tableName() {
    return 'persons';
  }

  // Optional JSON schema. This is not the database schema. Nothing is generated
  // based on this. This is only used for validation. Whenever a model instance
  // is created it is checked against this schema. http://json-schema.org/.
  static get jsonSchema() {
    return {
      type: 'object',
      required: ['firstName', 'lastName'],

      properties: {
	id: { type: 'integer' },
	parentId: { type: ['integer', 'null'] },
	firstName: { type: 'string', minLength: 1, maxLength: 255 },
	lastName: { type: 'string', minLength: 1, maxLength: 255 },
	age: { type: 'number' },
	address: {
	  type: 'object',
	  properties: {
	    street: { type: 'string' },
	    city: { type: 'string' },
	    zipCode: { type: 'string' }
	  }
	}
      }
    };
  }

  // This object defines the relations to other models.
  static get relationMappings() {
    return {
      pets: {
	relation: Model.HasManyRelation,
	// The related model. This can be either a Model subclass constructor or an
	// absolute file path to a module that exports one.
	modelClass: Animal,
	join: {
	  from: 'persons.id',
	  to: 'animals.ownerId'
	}
      }
    };	
  }
}

module.exports = Person;