Model validation

Here we'll talk about the content of the @banquette/model-validation package.

Its content is at the crossroad between the @banquette/model and @banquette/validation packages. The goal of this package is to avoid making them inter-dependent.

This package is very light and only contains a decorator and a service.

@Assert

@Assert is a decorator you can put on the properties of your models to validate them:

import { Assert } from '@banquette/model-validation';
import { NotEmpty } from '@banquette/validation';

class Article {
    @Assert(NotEmpty())
    public title: string;
}

You can then validate it manually using the validate utility function:

import { validate } from '@banquette/model-validation';

const result = validate(new Article());
// Returns a ValidationResult

TIP

If you build a form using the transformers, the validators set using @Assert will automatically be added to the corresponding form components.

Metadata

The @Assert decorator is just a shortcut to registering a validator for a given couple constructor/attribute.

But you could do it manually:

import { Injector } from '@banquette/dependency-injection';
import { ModelValidationMetadataService } from '@banquette/model-validation';
import { NotEmpty } from '@banquette/validation';

const metadata = Injector.Get(ModelValidationMetadataService);

metadata.register(Article, 'title', NotEmpty());

TIP

A use case for this could be to validate an object literal (on which you can't add decorators).

---

But the real value of this service is that it centralizes the validators of a model so any module can access it.

That's for example how the validators are automatically assigned when a form is created by transforming a model.

To get the validator of a model property:

const validator: ValidatorInterface|null = metadata.get('ModelIdentifier', 'propertyName');

TIP

The model identifier can be a constructor or an alias.