Length Class

Build options hook. Merges default options into options object. This method gets called on init and is the ideal place to normalize your options. The presence validator is a good example to checkout

Used by all pre-defined validators to build an error message that is present in validators/message or declared in your i18n solution.

If we extended our default messages to include uniqueUsername: '{username} already exists', we can use this method to generate our error message.

validate(value, options) {
    const exists = false;
  
    // check with server if username exists...
  
    if(exists) {
      // The username key on the options object will be used to create the error message
      options.username = value;
      return this.createErrorMessage('uniqueUsername', value, options);
    }
  
    return true;
  }
  

If we input johndoe and that username already exists, the returned message would be 'johndoe already exists'.

Easily compose complicated validations by using this method to validate against other validators.

validate(value, options, ...args) {
    let result = this.test('presence', value, { presence: true }, ...args);
  
    if (!result.isValid) {
      return result.message;
    }
  
    // You can even test against your own custom validators
    result = this.test('my-validator', value, { foo: 'bar' }, ...args);
  
    if (!result.isValid) {
      return result.message;
    }
  
    result = this.test('number', value, { integer: true }, ...args);
  
    // You can easily override the error message by returning your own.
    if (!result.isValid) {
       return 'This value must be an integer!';
     }
  
    // Add custom logic...
  
    return true;
  }
  

Used to retrieve the value to validate. This method gets called right before validate and the returned value gets passed into the validate method.