ActiveJDBC: Review the architecture for converters

[ipolevoy]

It seems to have a few flaws:

1. The model.set(attr, val) method calls a model.get(attr), which is not semantically correct
2. The converters are called inside the get(attr) as well as inside the set(attr)
3. This is not working, but we'd expect this world: model.set("created_at", "10/11/2022");
4. The Converted API is obtuse with too much to implement by a framework user. Needs to be simplified.

[ipolevoy]

related issue: #1241

[Dieken]

I just did some dirty hack to make ActiveJDBC can accept an encrypted object for query parameters and return encrypted object too from result set.

public class NameEnc {
    private String encrypted;
   ...
   public void setEncrypted(String s) { ... }
   public String getEncrypted() { ... }

    public static class ActiveConverter implements org.javalite.conversion.Converter<Object, Object> {

        public static final ActiveConverter INSTANCE = new ActiveConverter();

        @Override
        public boolean canConvert(Class src, Class dst) {
            return true;
        }

        @Override
        public Object convert(Object src) {
            if (src == null) {
                return null;
            }

            if (src instanceof NameEnc) {
                return ((NameEnc) src).getEncrypted();
            } else if (src instanceof String) {
                // XXX: ActiveJDBC actually always requires String for VARCHAR column,
                // XXX: set() and get() from user code have elements[3] not in ActiveJDBC code,
                // XXX: so it returns Encrypted only for user code.
                StackTraceElement[] elements = Thread.currentThread().getStackTrace();
                boolean internalCall = elements[3].getClassName().startsWith("org.javalite.activejdbc.");
                if (internalCall) {
                    return src;
                } else {
                    NameEnc e = new NameEnc();
                    e.setEncrypted((String) src);
                    return e;
                }
            } else {
                throw new UnsupportedOperationException("can't convert from class " + src.getClass());
            }
        }
    }
}

My entity class:

@Table("TEST.account")
public class AccountModel extends Model {

    static {
        convertWith(NameEnc.ActiveConverter.INSTANCE, "name_enc");
        ...
    }
}

[Dieken]

Possible converter interface:

public interface Converter<T> {
      // cls is required so that we can share an converter among sub classes of T
      T fromDatabase(ResultSet rs, int i, Class<T> cls);

      void toDatabase(PreparedStatement ps, int i, T t);
}

The objects in get(), set() should be just Java object, they are mapped to JDBC type only when call into JDBC.

[ipolevoy]

@Dieken, thanks for the idea, but I have a much simpler implementation for what you are doing here. I will publish a blog article on the topic sometime this week, and share it with you.

[Dieken]

Two month passed, just a ping … ;-)

[ipolevoy]

@Dieken, sorry for the late response. I will get this published in the next 3 days,