REST Data Validator

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Nested Validators ​

The nested validator is a powerful tool for validating nested and complex data structures. It uses a combination of individual validators to validate different parts of the data structure.

Creating Validators ​

First, we create individual validators for each type of object we want to validate. For example, if we want to validate objects of the User, Product, and Order classes, we create a validator for each one:

typescript
const isUserValidator: IValidator<any> = simpleValidatorFactory<any>({
  condition: (value) =>
    value instanceof User && value.name.startsWith("valid") && value.age > 18,
  errorMessage: "Value is not a valid User.",
});

const isProductValidator: IValidator<any> = simpleValidatorFactory<any>({
  condition: (value) =>
    value instanceof Product &&
    value.name.startsWith("valid") &&
    value.price > 10,
  errorMessage: "Value is not a valid Product.",
});

const isOrderValidator: IValidator<any> = simpleValidatorFactory<any>({
  condition: (value) =>
    value instanceof Order &&
    value.user instanceof User &&
    value.products.every((product) => product instanceof Product),
  errorMessage: "Value is not a valid Order.",
});

Creating the Complex Validator ​

Next, we combine these validators into a complex validator:

typescript
const complexClassValidator: IValidator<any> = combinedValidatorFactory([
  {
    validator: isUserValidator,
    typeGuard: (value: any): value is User => value instanceof User,
  },
  {
    validator: isProductValidator,
    typeGuard: (value: any): value is Product => value instanceof Product,
  },
  {
    validator: isOrderValidator,
    typeGuard: (value: any): value is Order => value instanceof Order,
  },
]);

Using the Complex Validator ​

Finally, we use the complex validator to validate our data structures:

typescript
const options: INestedValidationOptions<any> = {
  validator: complexClassValidator,
  validationOptions: {},
  each: true,
};

const value = {
  user: new User("validUser", 20),
  order: new Order(new User("validUser", 20), [
    new Product("validProduct", 15),
    new Product("validProduct", 15),
  ]),
  products: [new Product("validProduct", 15), new Product("validProduct", 15)],
};

const validationResult = validateNested(value, options);

In this example, validationResult.isValid will be true if all objects pass their corresponding validations, and false otherwise. Specific error messages can be found in validationResult.errors.