com.googlecode.objectify.impl.translate

Interface Translator<T>

All Known Implementing Classes:

AbstractTranslator, ClassTranslator, CollectionTranslatorFactory.CollectionListNodeTranslator, EmbedMapTranslatorFactory.MapMapNodeTranslator, EntityClassTranslator, ListNodeTranslator, MapifyTranslatorFactory.MapifyListNodeTranslator, MapNodeTranslator, PropertyValueNodeTranslator, ValueTranslator

public interface Translator<T>

A translator knows how convert between POJO objects and the EntityNode tree structure that Objectify can persist. In principle, this is similar to how a JSON object mapper works. Each node in the object graph corresponds to a node in the EntityNode graph.

Translators are composed of other translators; through a chain of these a whole entity object is assembled or disassembled.

Author:

Jeff Schnitzer

Method Summary

Methods

Modifier and Type	Method and Description
T	load(Node node, LoadContext ctx) Loads the content of the specified node, returning the pojo equivalent.
Node	save(T pojo, Path path, boolean index, SaveContext ctx) Translates the pojo into an EntityNode format.

Method Detail

load

T load(Node node,
     LoadContext ctx)
       throws SkipException

Loads the content of the specified node, returning the pojo equivalent.

There is one special return value: If a Result is returned, the content of the Result will be used instead, but delayed until ctx.done() is called. This happens at the end of a "round" of load operations and is the magic trick that makes populating entity references work efficiently.

Parameters:

node - is the part of the entity tree we are transforming.

ctx - holds state information during an entity load.

Returns:

an assembled pojo corresponding to the node subtree; if null is returned, that is the real value!

Throws:

SkipException - if the subtree should not be loaded into a containing entity

See Also:

LoadEngine

save

Node save(T pojo,
        Path path,
        boolean index,
        SaveContext ctx)
          throws SkipException

Translates the pojo into an EntityNode format. Note that all stored values (even terminal properties) are associated with a node.

Parameters:

pojo - is an object from the pojo entity graph; possibly the whole graph

path - is the path that the entitynode will be created with - the path to the pojo

index - is whether the instruction so far is to index or not index property values

Returns:

an EntityNode relevant to the pojo

Throws:

SkipException - if this subtree should not be saved.