com.googlecode.objectify.impl

Class Transmog<T>

java.lang.Object

com.googlecode.objectify.impl.Transmog<T>

public class Transmog<T>
extends Object

Transmogrifies POJO entities into datastore Entity objects and vice-versa.

TODO: long explanation of how this works.

Author:

Jeff Schnitzer

Constructor Summary

Constructors

Constructor and Description
Transmog(ObjectifyFactory fact, Class<T> clazz) Creats a transmog for the specified class, introspecting it and discovering how to load/save its properties.

Method Summary

Methods

Modifier and Type	Method and Description
KeyMetadata<T>	getKeyMetadata()
Node	load(com.google.appengine.api.datastore.Entity fromEntity) Turn the Entity into the hierarchical set of Nodes that the translation system understands.
T	load(com.google.appengine.api.datastore.Entity fromEntity, LoadContext ctx) Create a pojo from the Entity.
T	load(Node root, LoadContext ctx) Public just for testing
com.google.appengine.api.datastore.Entity	save(Node root) Turn a hierarchical series of Nodes into the standard Entity storage format.
com.google.appengine.api.datastore.Entity	save(T fromPojo, SaveContext ctx) Creates an Entity that has been set up with the content of the pojo, including key fields.
Node	saveToNode(T fromPojo, SaveContext ctx) Public just for testing

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Transmog

public Transmog(ObjectifyFactory fact,
        Class<T> clazz)

Creats a transmog for the specified class, introspecting it and discovering how to load/save its properties.

Method Detail

getKeyMetadata

public KeyMetadata<T> getKeyMetadata()

load

public T load(com.google.appengine.api.datastore.Entity fromEntity,
     LoadContext ctx)
       throws LoadException

Create a pojo from the Entity.

Parameters:

fromEntity - is a raw datastore entity

Returns:

the entity converted into the relevant pojo

Throws:

LoadException

load

public T load(Node root,
     LoadContext ctx)
       throws LoadException

Public just for testing

Throws:

LoadException

save

public com.google.appengine.api.datastore.Entity save(T fromPojo,
                                             SaveContext ctx)

Creates an Entity that has been set up with the content of the pojo, including key fields.

Parameters:

fromPojo - is your typed entity

saveToNode

public Node saveToNode(T fromPojo,
              SaveContext ctx)

Public just for testing

load

public Node load(com.google.appengine.api.datastore.Entity fromEntity)

Turn the Entity into the hierarchical set of Nodes that the translation system understands. This is done in two steps. The first converts to a literal structure of the Entity - this is normally the same as the POJO structure, but @Embed collections are "collectionized" such that the leaf property values are the collections. The second step de-collectionizes the entity nodes, repositioning the collections from the leaf levels up to the place in the hierarchy where the embedded classes are.

Also adds id/parent fields to the root Node.

Public only for testing purposes.

P.S. an exercise for the reader: Try to do this in one pass! Watch out for the ^null collection.

Returns:

a root Node corresponding to the Entity, in a format suitable for translators.

save

public com.google.appengine.api.datastore.Entity save(Node root)

Turn a hierarchical series of Nodes into the standard Entity storage format. Unlike the load process, this happens in one step, going straight to the "collectionized" format that @Embed collections are stored in.

Public only so we can test.

Returns:

an Entity with the propery key set