Bean Validation Constrain once, validate everywhere

Transcription

1 Bean Validation Constrain once, validate everywhere Introduction to Bean Validation Faglig fredag, den 24. juni 2015 hos Lund & Bendsen Copyright 2016 Christian Damsgaard

2 JSR 303 / JSR 349 JSR 303 Bean Validation th July th. November JSR 349 Bean Validation th June th May Validating data is a common task that occurs throughout an application, from the presentation layer to the persistence layer. Often the same validation logic is implemented in each layer, proving to be time consuming and error-prone. To avoid duplication of these validations in each layer, developers often bundle validation logic directly into the domain model, cluttering domain classes with validation code that is, in fact, metadata about the class itself.

3 Bean Validation What is Bean Validation? Bean Validation is a Java specification which: lets you express constraints on object models via annotations lets you write custom constraints in an extensible way provides the APIs to validate objects and object graphs provides the APIs to validate parameters and return values of methods and constructors reports the set of violations (localized) runs in Java SE but is integrated in Java EE (6 and 7) kilde:

4 What can be validated Constructor methods paramters Non-static methods parameters Individual parameters Cross parameter Return values Non-static class fields Note that declaring these constraints does not automatically cause their validation when the concerned methods are invoked. It's the responsibility of an integration layer to trigger the validation of the constraints using a method interceptor, dynamic proxy or similar.

5 Build (cascade validation)

6 Example public class User { private public String get () { return ; } } public void set (string ) { this. = ; } public class UserService { public void createuser(@ String String name) {... } }

7 Custom validation Annotation

8 Custom validation Validator

9 Custom validation Usage

10 Who can validate for us? You (Java SE): ValidatorFactory factory = Validation.buildDefaultValidatorFactory(); Validator validator = factory.getvalidator(); validator.validate(object); Spring containers Hibernate JEE containers

11 Validation result

12 Message & max=10, message = Between {min} and {max} ) The validation messages resource bundle and the locale variants of this resource bundle contain strings that override the default validation messages The validation messages resource bundle is typically a properties file, ValidationMessages.properties, in the default package of an application Locale variants of ValidationMessages.properties are added by appending an underscore and the locale prefix to the base name of the file. For example, the Danish locale variant resource bundle would be ValidationMessages_da.properties

13 Validation groups It is possible to limit a validation by specifying a validation group All build-in validation annotations have a group attribute A group is just an interface A group interface can be inherited public interface Read; public interface Write; public interface Create; public interface = { Create.class } = { Read.class, Write.class, Delete.class } ) private Long primarykey; validator.validate(record, Create.class)

14 Validate the validations! Create unit test which checks for correct validation annotations coverage

15 Fin Christian Damsgaard