Custom validation

Errors transformation and custom validation

One way to convert errors and perform custom validation is to extend the Validator class. Example.

Note

This customization will be applied only during full form validation.

For more information see Validator.

function customValidate(value: SchemaValue | undefined): ValidatorError<ErrorObject>[] {
  const { pass1, pass2 } = value as {
    pass1: string;
    pass2: string;
  };
  if (pass1 !== pass2) {
    return [
      {
        instanceId: "root_pass2",
        propertyTitle: "Repeat password",
        message: "Passwords don't match.",
        error: {} as ErrorObject,
      },
    ];
  }
  return [];
}

class CustomAjvValidator extends AjvValidator {
  override validateFormData(
    schema: Schema,
    formData: SchemaValue | undefined
  ): ValidatorError<ErrorObject>[] {
    // Errors transformation
    const errors = super.validateFormData(schema, formData).map((error) => {
      if (
        error.error.keyword === "minimum" &&
        error.error.schemaPath === "#/properties/age/minimum"
      ) {
        return Object.assign({}, error, {
          message: "You need to be 18 because of some legal thing",
        });
      }
      return error;
    });
    // Custom validation
    return errors.concat(customValidate(formData))
  }
}