Re: [Simple-support] Creating a "short" serialization

[Niall G. <gal...@ya...>]

Hi,

There is a way you could do this, don't know how well
it would suit you. But the @Resolve and @Replace
annotations are used in situations like this. Anything
you can do with the readResolve and writeReplace for
conventional object serialization can be done with
these annotations. Here is an example of what you
might do.


@Root
public class CompleteObject {

   @Attribute
   private String name;

   @Element
   private String id;

   @Element
   private Stirng address;

   public CompleteObject() {
      super();                     
   }

   public CompleteObject(String name, String id) {
      this.name = name;
      this.id = id;      
   }

   @Replace
   private Object getPrimaryKey() {
      return new PrimaryKey(name, id);
   }

   @Root
   private static class PrimaryKey {

      @Attribute
      private String name;

      @Element
      private String id;

      public PrimaryKey() {
         super();
      }

      public PrimaryKey(String name, String id) {
         this.name = name;
         this.id = id;
      }

      @Resolve
      private Object getCompleteObject() {
         return new CompleteObject(name, id);         
    
      }
   }
}

If you pair this with a custom Strategy implementation
then you can ensure the class="" attributes can be
replaced with other tokens to indicate what objects to
use. This above example is obviously not very useful,
but when used properly @Replace and @Resolve can be
quite powerful.

Niall

--- Ben Wolfe <si...@be...> wrote:

> 
> We have several places in our code where we could
> benefit from a shorter 
> serialization.  We don't need to serialize the
> entire object, just the 
> primary keys of the object.
> 
> I haven't been able to find a way to do this yet. 
> Did I miss something? 
> Is there a way to do it currently?
> 
> My thoughts on how to implement it:
> 
> The primary key attributes/elements would need to be
> annotated.  The 
> most general way to do it would be to add a String
> "tag" option to the 
> "Attribute" and "Element" annotations.  The tag
> would be a string that 
> groups certain attributes together and can be used
> later.
> I don't know why it would be necessary right now,
> but we could have any 
> number of "sets of serializations" with any named
> tag we want: A "Short" 
> one that would (de)derialize to just the primary
> keys, a "medium" one 
> that would (de)serialize to only certain attributes,
> and then the 
> default that would work normally using all
> annotations (as it does now).
> 
> 1) It could be done with a custom Strategy, but
> alas, "Strategy"s are 
> only notified about elements (via setElement(...)). 
> If there were a 
> setAttribute(...) method that was called on
> strategies, the custom 
> strategy could look up the Object's annoations, find
> the right ones, and 
> only let certain attributes and elements be written
> out to the DOM. 
> This has the benefit of the least about of core
> simpleframework code 
> changes.
> 
> 2) The Source object could have a "List<String>
> tags" object that holds 
> the current tags to serialize on.  The Source can
> tell the scanner what 
> tags to look for.  Only the matching tags are
> included as attributes and 
> elements for objects.  The Persister/Serializer will
> need to have a 
> setTags() method that it can pass on to the Source.
> The downside of this approach is that more code
> would have to be 
> changed. The benefit is that not all of the
> attributes/elements would be 
> looped over unnecessarily if there is only a "short"
> serialization going on.
> 
> I am happy to code this up and submit a patch. 
> However, I am not sure 
> which you would prefer.  There might be a third
> option that I'm missing. 
>   Please point me in the right direction if that is
> the case.
> 
> Thanks,
> Ben
> 
>
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