spring mvc nested model validation

Question

I have two models : User,Project

public class Project{
    private int id;
    @NotEmpty(message=\"Project Name can not be empty\")
    private          


        

Answer 1

Actually what you need to do is add @Valid on

private User manager;
private User operator;

like this

@Valid
private User manager;
@Valid
private User operator;

Answer 2

In your Controller you can add a custom validator:

@InitBinder
protected void initBinder(WebDataBinder binder) {
    binder.setValidator(new ProjectValidator());
}

In this validator, you could check the User objects or delegate to a UserValidator, as done here in the last paragraph before section 6.3

Answer 3

I did what Jerome Dalbert suggested and in addition added a custom BeanValidator for delegating the actual work of validating to a JSR 303 implementation.

The prefix is used to denote the path of the property in the form.

@Component
public class BeanValidator implements org.springframework.validation.Validator, InitializingBean {    

 private Validator validator;
 public void afterPropertiesSet() throws Exception {
  ValidatorFactory validatorFactory = Validation.buildDefaultValidatorFactory();
  validator = validatorFactory.usingContext().getValidator();
 }

 public boolean supports(Class clazz) {
  return true;
 }

 public void validate(Object target, Errors errors, String prefix) {
  Set<ConstraintViolation<Object>> constraintViolations = validator.validate(target);
  for (ConstraintViolation<Object> constraintViolation : constraintViolations) {
   String propertyPath = constraintViolation.getPropertyPath().toString();
   String message = constraintViolation.getMessage();
   errors.rejectValue(prefix + "." + propertyPath, "", message);
  }
 }

 public void validate(Object target, Errors errors) {
  validate(target, errors, "");
 }
}

and here how I used it in the UserValidator:

@Component
public class UserValidator implements Validator {

 @Autowired
 BeanValidator beanValidator;

 @Override
 public boolean supports(Class<?> clazz) {
  return User.class.equals(clazz);
 }

 @Override
 public void validate(Object target, Errors errors) {
  User user = (User) target;
  beanValidator.validate(user.getAddress(), errors, "address");
 }
}

References:

• http://blog.trifork.com/2009/08/04/bean-validation-integrating-jsr-303-with-spring/

Answer 4

Here's one possible solution.

Create the class below :

...
import org.springframework.validation.Validator;
...

@Component
public class ProjectValidator implements Validator {

    @Override
    public boolean supports(Class<?> clazz) {
        return Project.class.equals(clazz);
    }

    @Override
    public void validate(Object target, Errors errors) {
        Project project = (Project) target;

        /* Do your checks here */
        ...

        if (managerIdDoesNotMatch) {
            errors.rejectValue("manager.id", "your_error_code");
        }

        ...

        if (operatorIdDoesNotMatch) {
            errors.rejectValue("operator.id", "your_error_code");
        }

        ...
    }
}

And in your controller do something like :

...
public class ProjectController {

    @Autowired
    ProjectValidator projectValidator;

    ...

    @RequestMapping(...)
    public String yourCreateMethod(..., @ModelAttribute @Valid Project project, BindingResult result) {
        projectValidator.validate(project, result);           

        if (result.hasErrors()){
          // do something
        }
        else {
          // do something else
        }
    }

}

This should get you started. You could instantiate/set the validator differently, have a a user sub-validator, but you get the general idea.

References :

• Latest Spring validation documentation
• This Stack Overflow post about how to perform validation