Custom validation in objection.js

BaseModel.js

const { Model, AjvValidator } = require('objection');
const pluralize = require('pluralize');

class BaseModel extends Model {
  /**
   * Always use timestamps as default
   */
  static get timestamps() {
    return true;
  }

  /**
   * Use the lower case, plural model class name
   * as the table name
   */
  static get tableName() {
    return pluralize(this.name.toLowerCase());
  }

  /**
   * Set this directory as the model path so
   * they can get automatically imported in
   * `relationMappings` without circular dependencies
   */
  static get modelPaths() {
    return [__dirname];
  }

  /**
   * Override this to true whenever you want to
   * use `$customValidate` over `$validate`
   *
   * @returns {Boolean}
   */
  static get hasToCustomValidate() {
    return false;
  }

  /**
   * Return an array of the required fields to validate.
   *
   * @param {object} queryContext The context of the query. See http://vincit.github.io/objection.js/#context
   * @param {object} opts Options. Can be accessed to check if the query that is being
   * executed is an insert or an update query
   */
  // eslint-disable-next-line no-unused-vars
  static requiredFields(queryContext, opts) {
    return [];
  }

  /**
   * Create a custom validator, because we need
   * the $data feature, see https://github.com/epoberezkin/ajv#data-reference
   */
  static createValidator() {
    return new AjvValidator({
      onCreateAjv: () => {},
      options: {
        $data: true,
        allErrors: true,
        validateSchema: false,
        ownProperties: true,
        v5: true,
        coerceTypes: true,
        removeAdditional: true,
      },
    });
  }

  /**
   * Validates the model with a custom schema.
   * This is used over `$validate` whenever we want to
   * validate different attributes based on whether the model
   * is being created or updated
   */
  $customValidate(queryContext, opts) {
    const { jsonSchema } = this.constructor;
    jsonSchema.required = this.constructor.requiredFields(queryContext, opts);
    const validator = this.constructor.getValidator();

    const args = {
      json: this.$toJson(),
      model: this,
      options: { mutable: true },
      ctx: { jsonSchema },
    };

    validator.validate(args);
  }

  /**
   * Override with the ability to perform custom validation on
   * an insert operation
   */
  $beforeInsert(queryContext) {
    if (this.constructor.hasToCustomValidate) {
      this.$customValidate(queryContext, {
        isInsert: true,
      });
    }
  }

  /**
   * Override with the ability to perform custom validation on
   * an update operation
   */
  $beforeUpdate(opts, queryContext) {
    if (this.constructor.hasToCustomValidate && !opts.skipValidation) {
      this.$customValidate(queryContext, {
        isUpdate: true,
      });
    }
  }
}

module.exports = BaseModel;