Saturday, September 17, 2016

Wednesday, September 14, 2016

Injecting authenticated user into Spring MVC @Controllers

Injecting injecting authenticated user into Spring MVC handler method can be done with @AuthenticationPrincipal annotation and AuthenticationPrincipalArgumentResolver that is an implementation of Spring MVS MethodArgumentResolver. AuthenticationPrincipalArgumentResolver is registered by default with web security configuration (e.g. when you enable security with @EnableWebSecurity).

Saturday, May 14, 2016

Thymeleaf 3 - Get Started Quickly with Thymeleaf 3 and Spring MVC

Thymeleaf 3 release arrived. The new version brings plenty of new features like HTML5 support as well as Text templates support with no markup - [# th:utext="${thymeleaf.version}" /] , improved inline capabilities - <p>Thymeleaf [[${thymeleaf.version}]] is great!</p>, performence improvements and much more.

Thursday, April 7, 2016

Spring MVC: Trgger manual validation of a form object

Sometimes it may be needed to use manual validation in Spring MVC @Controller. This is very simple with Spring’s org.springframework.validation.ValidationUtils class. Learn how to invoke a validator in two different scenarios.

Scenario 1 - invoke validation

In this scenario, I have a user form with username field. Username field is validated with custom validator in order to verify the existance in e.g. database.

public class User {

    private String username;


In controller class I have a method that handles POST method of that object:

private org.springframework.validation.Validator validator;

@RequestMapping(value = "/user", method = RequestMethod.POST)
public String validate(@ModelAttribute User user, Errors errors) {

    ValidationUtils.invokeValidator(validator, user, errors);

    if (errors.hasErrors()) {
        // error, show errors to the user

    // success, form is valid!

org.springframework.validation.ValidationUtils is a class for invoking a org.springframework.validation.Validator.

Please note that user parameter is followed by org.springframework.validation.Errors object. Spring initializes this object but it is empty and can be be passed to a invokeValidator method.

Scenario 2 - invoke validation with hints

In this scenario, user form gets a bit more complicated:

@GroupSequence(value = {ValidationOrder.First.class, ValidationOrder.Second.class})
interface ValidationOrder {
    interface First {}
    interface Second {}

public class User {

    @UserExists(groups = ValidationOrder.First.class)
    @UserIsEntitledToDiscount(groups = ValidationOrder.Second.class)
    private String username;


Thanks to @GroupSequence I could decide about the order of validation. To trigger validation I need to pass an additional argument to invokeValidator method so the groups are correctly used:

ValidationUtils.invokeValidator(validator, user, errors, ValidationOrder.class);

Source code

The source code contains all three approaches, so that you can quickly compare them:

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Friday, March 4, 2016

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Tuesday, March 1, 2016

Quickstart: Angular2 with TypeScript and Gulp

Quickstart: Angular2 with TypeScript and Gulp

Angular2 is out. The new version of the framework is much simpler to learn thanks to easier and more concise concepts like component-based architecture, new dependency injection or built-in modularity. In this step-by-step tutorial you will learn how how to get started with Angular2 with TypeScript and Gulp. Source code available on Github.