com.googlecode.objectify.impl.translate

Interface Translator<P,D>

All Known Implementing Classes:

ClassTranslator, Creator, EmbeddedCreator, EntityCreator, EntityTranslator, NullSafeTranslator, ProjectionSafeTranslator, TranslatorRecycles, ValueTranslator

public interface Translator<P,D>

A translator knows how convert between POJO objects and the native datastore representation.

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

P is the pojo type. D is the datastore type.

Author:

Jeff Schnitzer

Method Summary

Methods

Modifier and Type	Method and Description
P	load(D node, LoadContext ctx, Path path) Loads the content of the specified datastore node, returning the pojo equivalent.
D	save(P pojo, boolean index, SaveContext ctx, Path path) Translates a pojo (or some component thereof) into a format suitable for storage in the datastore.

Method Detail

load

P load(D node,
     LoadContext ctx,
     Path path)
       throws SkipException

Loads the content of the specified datastore 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 native datastore entity tree we are transforming.

ctx - holds state information during an entity load.

path - is the current path to this translator

Returns:

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

Throws:

SkipException - if the return value should be abandoned.

See Also:

LoadEngine

save

D save(P pojo,
     boolean index,
     SaveContext ctx,
     Path path)
       throws SkipException

Translates a pojo (or some component thereof) into a format suitable for storage in the datastore.

Parameters:

pojo - is an object from the pojo entity graph; possibly the whole graph or possibly just a leaf field.

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

path - is the path that we have taken to get here, which could be long due to re-entrant translators (ie, an embedded pojo that also has a reference to the same class).

Returns:

something suitable for storage in the datastore.

Throws:

SkipException - if the return value should be abandoned