How to silently truncate strings while storing them when they are longer than the column length definition?

Question

I have a web app, using EclipseLink and MySQL for storing data. Some of these data are strings, ie varchars in the DB. In the code of entities, the strings have attributes

Answer 1

Another option is to declare a constant and reference it everywhere you need that length starting with the @Column annotation itself.

This constant can be then forwarded to a truncate function or a validation function that throw a preventive exception if the passed string is too long. This constant can also be re-used on some other layers such as a UI.

For example:

@Entity
public class MyEntity {
    public static final int NAME_LENGTH=32;

    private Long id;
    private String name;

    @Id @GeneratedValue
    public Long getId() {
        return id;
    }
    protected void setId(Long id) {
        this.id = id;
    }

    @Column(length=NAME_LENGTH)
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = JpaUtil.truncate(name, NAME_LENGTH);
    }
}

public class JpaUtil {
    public static String truncate(String value, int length) {
        return value != null && value.length() > length ? value.substring(0, length) : value;
    }
}