Java Bean Validation (JSR303) constraints involving relationship between several bean properties

Question

Say I have the following simple java bean:

class MyBean {
   private Date startDate;
   private Date endDate;
   //setter, getters etc...
}

Is there a mechanism in JSR 303 to create a custom validator that validates the constraint that startDate must be before endDate?

It seems to me to be a common use case, yet I cannot find any examples of this kind of multiple property relationsship constraint.

Answer 1

I can think of a few things to try.

You could create a Constraint with a target of the type itself with an appropriate validator:

@ValidateDateRange(start="startDate", end="endDate")
public class MyBean {

You could encapsulate a date range in a type and validate that:

public class DateRange {    
  private long start;
  private long end;

  public void setStart(Date start) {
    this.start = start.getTime();
  }

  // etc.

You could add a simple property that performs the check:

public class MyBean {
  private Date startDate;
  private Date endDate;

  @AssertTrue public boolean isValidRange() {
    // TODO: null checks
    return endDate.compareTo(startDate) >= 0;
  }