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) {
  var exists = false;

  options.description = 'Username';
  options.username = value;

  // check with server if username exists...

  if(exists) {
    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'.

Generate the needed depenent keys for this validator

Creates a new object and calls any option property that is a function with the validator context. This method is called right before validate and the returned object gets passed into the validate method as its options

The validate method is where all of your logic should go. It will get passed in the current value of the attribute this validator is attached to. Within the validator object, you will have access to the following properties:

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