Thymeleaf rejects null date - html

Question

I have this html code:
<input class="form-control col-sm-8" type="date" th:field="*{completiondate}">
and this model :
import java.math.BigDecimal;
import java.sql.Date;
import java.sql.Timestamp;
public class EventReport {
private Long id;
private Date creationdate;
private String status;
private Date completiondate;
...
}
completion date is not a required value and can be null sometimes. When user submits the post form I take the following
Field error in object 'treeTrimsEventReport' on field
'completiondate': rejected value [];
Obviously I don't have errors when I select a value for date and the app works fine.
How can I give null on completion date without errors?

Answer 1

I think it is a binding error.
You need to tell spring how to convert form data which comes as text (String) to the type in your model (here a Date).
You may do it with this annotation on the field in EventReport :
import org.springframework.format.annotation.DateTimeFormat
...
#DateTimeFormat(pattern = "yyyy-MM-dd")
private Date completiondate;
(change the pattern to match the one you wish to show to the user)
Spring gives you other option to tell it how to bind data.
Have a look at the reference manual, in this chapter for all options :
https://docs.spring.io/spring/docs/current/spring-framework-reference/web.html#mvc-ann-initbinder