modifty timestamp annotation

[GoogleCodeExporter]

   If Slim3 add a new modify timestamp annotation, it would be more easy to
incremental backup data which is modified since last backup timestamp.
Although it could be done by programmers to maintain such a property when
writing every entity, it would reduce the burden of programmers.

Original issue reported on code.google.com by mylee...@gmail.com on 2 May 2010 at 11:11

[GoogleCodeExporter]

Since slim3 doesn't use aop to detect dirty properties, it is reasonable that 
the
values of modify-timestamp-annotated properties will always be overridden by 
slim3.
The programmers have no responsibility for taking care of the
modify-timestamp-annotated properties.

Original comment by mylee...@gmail.com on 2 May 2010 at 11:19

[GoogleCodeExporter]

We will prepare AttributeListener for "Automatic Assigned Property" as follows:

public interface AttributeListener<T> {

  /**
   * This method is called before a model is put to datastore.
   * 
   * @param value the original property value
   * @return the automatic assigned value
   */
  T prePut(T value);
}

public class CreatedDate implements AttributeListener<Date> {
  public Date prePut(Date value) {
    if (value != null) {
      return value;
    }
    return new Date();
  }
}

public class UpdatedDate implements AttributeListener<Date> {
  public Date prePut(Date value) {
    return new Date();
  }
}

@Model
public class Xxx {
  ...
  @Attribute(listener = CreatedDate.class)
  private Date createdDate;

  @Attribute(listener = UpdatedDate.class)
  private Date updatedDate;
}

Original comment by higaya...@gmail.com on 2 May 2010 at 11:43

• Changed state: Accepted

[GoogleCodeExporter]

Original comment by higaya...@gmail.com on 2 May 2010 at 11:44

• Added labels: Version-1.0.4
• Removed labels: Version

[GoogleCodeExporter]

GJ!
One question: Can I use both listener in one property as below?

@Model
public class Xxx {
  ...
  @Attribute(listener = CreatedDate.class, listener = UpdatedDate.class)
  private Date modifyDate;
}

Original comment by mylee...@gmail.com on 3 May 2010 at 7:41

[GoogleCodeExporter]

> One question: Can I use both listener in one property as below?

No you can't. Just one listener.

Original comment by higaya...@gmail.com on 3 May 2010 at 9:04

[GoogleCodeExporter]

If I use UpdatedDate.class listener only as below, it seems (from the code) 
that 
modifyDate will be set to current time even upon entity creation (and that's 
what I 
want). Am I right?

@Attribute(listener = UpdatedDate.class)
  private Date modifyDate;

Original comment by mylee...@gmail.com on 3 May 2010 at 9:16

[GoogleCodeExporter]

Yes. You are right.

Original comment by higaya...@gmail.com on 3 May 2010 at 9:21

[GoogleCodeExporter]

Original comment by higaya...@gmail.com on 15 May 2010 at 8:07

• Added labels: Version-1.0.5
• Removed labels: Version-1.0.4

[GoogleCodeExporter]

Original comment by higaya...@gmail.com on 8 Jul 2010 at 9:16

• Changed state: Fixed