[FIXED] Is there a way to validate fields in a Request Object that am using as a wrapper, such that one of them is optional

Issue

Controller Code:

    @RequestMapping(value="/update", method=RequestMethod.POST, produces = 
"application/json; charset=utf-8")
   @ResponseBody
    public ResponseEntityWrapper update(
    HttpServletRequest request, 
    @RequestBody @Valid InputForm form,
    HttpServletResponse response
    )  {
     //logic
     }

InputForm:

     public class InputForm{

    @NotNull
    private String formId;

    private List<Employee> addEmpList;
    private List<Employee> removeEmpList;

    //Other fields & getters & setters.....

   }

Employee:

    public Employee{

   @NotNull
   private String empId;
   private String name;
   //Other fields and getters and setters.....

   }

When the request to Controller's update is method, I would like to have InputForm validated - Atleast one of the fields in it is mandatory. ie., both addEmpList, removeEmpList cannot be null. And empId in Employee should not be null.

How do I do this?

Solution

This can be achieved using javax.validation.Constraint. Annotate your controller using @Validated annotation, and you can create your constraints as below:

Controller

import com.example.model.Employee;
import com.example.model.InputForm;
import com.example.service.MyService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.*;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.validation.Valid;
import java.util.List;

@RestController
@Validated
public class MyController {

    @Autowired
    private MyService myService;

    @RequestMapping(value="/update", method= RequestMethod.POST, produces = "application/json; charset=utf-8")
    @ResponseBody
    public ResponseEntity<List<Employee>> update(
            HttpServletRequest request,
            @CheckAtLeastOnePresentConstraint @RequestBody @Valid InputForm form,
            HttpServletResponse response
    )  {
        return new ResponseEntity<List<Employee>>(myService.getEmployees(form), HttpStatus.OK);
    }
}

Contraint Interface:

import java.lang.annotation.*;

import javax.validation.Constraint;
import javax.validation.Payload;


@Constraint(validatedBy = CheckOneValuePresent.class)
@Target( { ElementType.PARAMETER })
@Retention(RetentionPolicy.RUNTIME)
public @interface CheckAtLeastOnePresentConstraint {
    String message() default "At least one of the values removeEmpList or addEmpList must be present";
    Class<?>[] groups() default {};
    Class<? extends Payload>[] payload() default {};
}

And your CustomValidator class

import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;
import javax.validation.constraintvalidation.SupportedValidationTarget;
import javax.validation.constraintvalidation.ValidationTarget;

@SupportedValidationTarget(ValidationTarget.PARAMETERS)
public class CheckOneValuePresent implements ConstraintValidator<CheckAtLeastOnePresentConstraint, InputForm> {

    @Override
    public boolean isValid(InputForm inputForm,
        ConstraintValidatorContext cxt) {
        return inputForm.getAddEmpList() != null || inputForm.getRemoveEmpList() != null;
    }
}

Hope this will help.

Answered By - YoManTaMero
Answer Checked By - Katrina (JavaFixing Volunteer)