Postgres empty varchar as null instead of empty string in Spring Data JPA

I have a table with a varchar column which represent a data in yyyy-mm-dd format. However, this field could be an empty string.

| id   | serial      |
| date | varchar(10) |

I have my entity defined as


import jakarta.persistence.*;

@Entity
class Table {
  @Id
  private long Id;
  private LocalDate date; 
}

And I use a JpaRepository findById()

The problem arise when column date's value is an empty string "" It's trying to convert binary empty string to a date from org.postgresql.jdbc.TimestampUtils. I am getting an IndexOutOfBoundException because it's not expecting the string to be empty.

I have a few solutions but they don't seem clean enough.

The most obvious solution would be avoid writing empty string to date column. But this requires upstream change.
Second solution is change date in my entity from LocalDate to String and do a manual conversion to LocalDate to a DTO. During this conversion, I have more freedom to convert empty string or null object if needed. I am not crazy about this solution since it adds extra step.

So I am wondering if Jakarta entity has built in annotation where I could consider empty string as null? Or is there any other elegant way to circumvent this problem?

Solution

You can use AttributeConverter to convert empty string to null.

import jakarta.persistence.AttributeConverter;
import jakarta.persistence.Converter;

import java.time.LocalDate;

@Converter
public class LocalDateConverter implements AttributeConverter<LocalDate, String> {
    @Override
    public String convertToDatabaseColumn(LocalDate date) {
        if (date == null) {
            return null;
        }
        return date.toString();
    }

    @Override
    public LocalDate convertToEntityAttribute(String str) {
        if (str == null || str.isEmpty()) {
            return null;
        }
        return LocalDate.parse(str);
    }
}

then use @Convert

@Convert(converter = LocalDateConverter.class)
private LocalDate date;