Validation API

PAMELA framework natively offers a validation definition scheme at ModelEntity level. To be validable, the ModelEntity support interface must extends Validable interface. This allows to define a set of ValidationRules.

Following excerpt of code shows how a ValidationRule should be declared on a ModelEntity, exposed as a inner static class annotated with @DefineValidationRule annotation. In this example, an instance of Book should have an ISBN code. Note that relatively to Java semantics, any instance of Book may have null ISBN code. Only the validation level raises a validation rule violation.

@ModelEntity
public interface Book extends AccessibleProxyObject, Validable {
    ...

    @Getter("ISBN")
    public String getISBN();

    @Setter("ISBN")
    public void setISBN(String value);

    @DefineValidationRule
    public static class BookShouldHaveAnISBN extends ValidationRule<BookShouldHaveAnISBN, Book> {
        public BookShouldHaveAnISBN() {
            super(Book.class, "Book should have an ISBN code");
        }

        @Override
        public ValidationIssue<BookShouldHaveAnISBN, Book> applyValidation(Book book) {
            if (book.getISBN() == null) {
                return new ValidationError<>(this, book, "Book does not define ISBN code");
            }
            return null;
        }
    }

}

Validation performing API is presented on following excerpt of code. A ValidationReport is generated as result artefact for the validation of a Validable object, given the ValidationModel directely computed from ModelContext.

// Instantiate the model
ModelContext modelContext = ModelContextLibrary.getModelContext(Library.class);
... 
// instantiate here the factory and myLibrary object
ValidationModel validationModel = new DefaultValidationModel(modelContext);
ValidationReport validationReport = new ValidationReport(validationModel, myLibrary);

assertEquals(2, validationReport.getErrorsCount());
// myLibrary object contains here two books without ISBN code
// VALIDATION / ERROR: Book does not define ISBN code
// VALIDATION / ERROR: Book does not define ISBN code