spring boot - calculated field

Question

So, I have an entity, that has field start_date (java.util.Date is the type).

I want to have another field, that would automatically populate with integer that corresponds to day of week (as a number 1 for sunday, 2 for monday, etc.) of starting date.

Here's fragment of my entity:

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Integer id;

@DateTimeFormat(pattern = "yyyy-MM-dd")
@Temporal(TemporalType.DATE)
private Date start_date;

I've tried to add the calculated field in the following way:

@Column(name = "weekday")
@Formula("(select dayofweek(l.start_date) from Lesson l where l.id = id)")
private Integer weekDay;

However, when looking at the Lesson table in H2 console, there's no such column as "weekday"

I also tried other option - without @Formula annotation and with a setter that takes start_date parameter, but I guess this setter is never called, since the column "weekday" is populated with null. Here's the setter I've tried to use as an alternative solution:

    public void setWeekDay(Date start_date) {
    Calendar c = Calendar.getInstance();
    c.setTime(start_date);
    this.weekDay = c.get(Calendar.DAY_OF_WEEK);
}

It's obvious that I'm missing something here, it's probably because I'm still learning Spring boot...

To sum up - I want to have a column in table Lesson, that is calculated from another column of the same table.

spring boot - calculated field

2 Answers