Spring MVC form validation - spring

Question

my problem is that I have a form which has html select element with some choosing option value & I want to validate those value using :
org.hibernate.validator.constraints
or
javax.validation.constraints
annotations. here is my select element:
<select name="status" id="tbSelect">
<option value="ACTIVE">ACTIVE</option>
<option value="LISTEN">LISTEN</option>
<option value="DOWN">DOWN</option>
</select>
how I can for example validate the value of the options(DOWN,LISTEN,ACTIVE) inside the select element by using the annotation validators which I mention above?
my form is like this :
<form:form action="../agents/add" method="POST" commandName="myAgent">
<form:select id="tbSelect" path="state">
<form:option value="ACTIVE" path="state">ACTIVE</form:option>
<form:option value="LISTEN" path="state">LISTEN</form:option>
<form:option value="DOWN" path="state">DOWN</form:option>
</form:select>
I have defined my controller method like this:
#RequestMapping(value = "agents/add", method = RequestMethod.POST)
public String addAgentSubmit(#ModelAttribute("myAgent") #Valid final AgentValidator agent, BindingResult result, RedirectAttributes redirect) {
if (result.hasErrors()) {
return "admin/agent/add";
}
...
}
and I also define a ModelAttribute like this:
#ModelAttribute("myAgent")
public AgentValidator getLoginForm() {
return new AgentValidator();
}
Here is my AgentValidator class also:
public class AgentValidator {
#NotEmpty(message = "your state can not be empty !")
private String state;

Answer 1

Since your state field looks more like an enumeration, first of all I would recommend to change state field into enum, let Spring MVC to bind that field and use only #NotNull annotation:
public class AgentValidator {
#NotNull(message = "your state can not be empty !")
private AgenState state;
Where AgentState is:
public enum AgentState {
DOWN,LISTEN,ACTIVE
}
But if for certain reasons you can't change your model, then you may use custom constraints.
Particular you need to create your annotation AgentStateConstraint:
#Target( { METHOD, FIELD, ANNOTATION_TYPE })
#Retention(RUNTIME)
#Constraint(validatedBy = AgentStateConstraintValidator.class)
#Documented
public #interface AgentStateConstraint {
String message() default "Some message";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
}
Then you need to create validator AgentStateConstraintValidator:
public class AgentStateConstraintValidator implements ConstraintValidator<AgentStateConstraint, String> {
//Accepted values
private static final Set<String> ACCEPTED_VALUES = new HashSet<String>(
Arrays.asList(
"DOWN",
"LISTEN",
"ACTIVE"
)
);
public void initialize(AgentStateConstraint constraintAnnotation) {
}
public boolean isValid(String object, ConstraintValidatorContext constraintContext) {
return ACCEPTED_VALUES.contains(object);
}
}