On the fly / dynamic CakePhp 3 Validation and FormHelper - validation

Question

I am creating a 'form editor' in CakePHP.
The interface allows the user to choose validations to apply to the fields, e.g. Numeric, Email etc.
As such I need to dynamically create validation for the model based on the user input. For this I can use the Validation object: https://book.cakephp.org/3.0/en/core-libraries/validation.html
I want to take advantage of the features of FormHelper, for example, automatically outputting error messages for fields.
I can see how to use a hard-coded validator from the model to do this by setting the validator in the context option for Form->create() - but how do I use a customer $Validator object which has been dynamically created?
Clarification:
I have some code in my controller:
//get the form configuration
$form = $this->Forms->get($id, ['contain'=>['FormFields'=>['Validations']]]);
//set up validation based on the configuration
$validator = new Validator();
foreach($form->form_fields as $field){
...
if($field->required) $validator->notBlank($field->field_name);
}
$table = TableRegistry::get($form->type);
$table->setValidator($validator);
Unfortunately setValidator() is not a method of TableRegistry.
If I set the validation up in the model, I would need the $id parameter to look up the correct form configuration.

Answer 1

I added the following code to my model:
protected $validator = null;
public function validationDefault(Validator $validator){
if($this->validator != null) return $this->validator;
return $validator;
}
public function setValidator(Validator $validator){
$this->validator = $validator;
}
So the default validator can effectively be set via the setValidator method.
Then in my controller:
//get the form configuration
$form = $this->Forms->get($id, ['contain'=>['FormFields'=>['Validations']]]);
//set up validation based on the configuration
$validator = new Validator();
foreach($form->form_fields as $field){
...
if($field->required) $validator->notBlank($field->field_name);
}
$table = TableRegistry::get($form->type);
$table->setValidator($validator);
I hope this is useful for others.