How to use ValidationUtils in spring - spring

Question

I want to use ValidationUtils as follows. But I cannot instantiate errors object since Errors is an Interface. Can you tell me how I can make this working without using a validator?
if(visitorDetails==null)
{
Errors errors;
visitorDetails=new Visitor();
ValidationUtils.rejectIfEmpty(errors, "VisitorInfo", "Selected Visitor Details Not Found");
}

Answer 1

Read this : Validation...
However you must implement the Validation interface in a class, and than use it to validate your object, and to do that you autowire validator in your controller..
This is an example:
public class PersonValidator implements Validator {
/**
* This Validator validates *just* Person instances
*/
public boolean supports(Class clazz) {
return Person.class.equals(clazz);
}
public void validate(Object obj, Errors e) {
ValidationUtils.rejectIfEmpty(e, "name", "name.empty");
Person p = (Person) obj;
if (p.getAge() < 0) {
e.rejectValue("age", "negativevalue");
} else if (p.getAge() > 110) {
e.rejectValue("age", "too.darn.old");
}
}
}
and in your controller:
....
#Autowired
private PersonValidator personValidator;
#InitBinder
protected void initBinder(final HttpServletRequest request, final ServletRequestDataBinder binder) {
binder.addValidators(personValidator);
}
...

Answer 2

Assuming you are using Spring Boot.
If using application.properties (under project/src/resources) put the following in it:
spring.messages.basename=validation
Now put a validation.properties (under project/src/resources) and put the following (for example) in it:
NotEmpty=This field is required.
Your model (AppUser in this case) should have:
private String useremail;
getters/setters;
Create a component (Class) like this (example):
#Component
public class UserAddValidator implements Validator {
#Autowired
private UserService userService;
#Override
public boolean supports(Class<?> aClass) {
return AppUser.class.equals(aClass);
}
#Override
public void validate(Object o, Errors errors) {
AppUser user = (AppUser) o;
ValidationUtils.rejectIfEmptyOrWhitespace(errors, "useremail", "NotEmpty");
}
}
The following goes to your controller:
#RequestMapping(value = "registration", method = RequestMethod.POST)
public String registration(#ModelAttribute("userForm") AppUser userForm, BindingResult bindingResult, Model model) {
useraddValidator.validate(userForm, bindingResult);
if (bindingResult.hasErrors()) {
return "userregistration";
}
userService.save(userForm);
model.addAttribute("success", "User " + userForm.getUsername() + " created successfully");
return "success";
}
Last but not the least, in your view put similar to this:
<div class="row">
<label class="col-md-3" for="useremail">Email-ID</label>
<div class="col-md-8">
<spring:bind path="useremail">
<div class="form-group ${status.error ? 'has-error' : ''}">
<form:input type="text" path="useremail" class="form-control"
placeholder="Email-id" autofocus="true"></form:input>
<form:errors path="useremail">${emailerror}</form:errors>
</div>
</spring:bind>
</div>
</div>
The result should look (something) like below:
You can look HERE for more validations.

Answer 3

If I understand your question correctly you want to get the errors object.
In your case I would suggest below approach.
if(visitorDetails==null)
{
visitorDetails=new Visitor();
Errors errors = new BeanPropertyBindingResult(visitorDetails, visitorDetails.getClass().getName());
ValidationUtils.rejectIfEmpty(errors, "VisitorInfo", "Selected Visitor Details Not Found");
}
Let me know if you need more help.

Answer 4

you can use it to make some constraint on some of your field like show error when the field is empty or emptywithspace , this class already contain some static method that can do that
below an exemple for using ValidationUtils class
public class UserValidator implements Validator {
public boolean supports(Class clazz) {
// TODO Auto-generated method stub
return Employee.class.equals(clazz);
}
public void validate(Object target, Errors errors) {
// TODO Auto-generated method stub
ValidationUtils.rejectIfEmpty(errors, "email", "email");
ValidationUtils.rejectIfEmpty(errors, "password", "password");
Employee emplo = (Employee) target;
if(emplo.getEmail() != null && emplo.getEmail()=="aa") {
errors.rejectValue("email", "email invalide ");
}