Package com.googlecode.objectify.impl.translate

Class NullSafeTranslator<P,D>

java.lang.Object

com.googlecode.objectify.impl.translate.NullSafeTranslator<P,D>

All Implemented Interfaces:

Translator<P,D>

Direct Known Subclasses:

ClassTranslator, ValueTranslator

public abstract class NullSafeTranslator<P,D>
extends Object
implements Translator<P,D>

Handles null checking so we don't have to do it everywhere. Handles NullValue where appropriate.

Author:

Jeff Schnitzer

Constructor Summary

Constructors

Constructor	Description
NullSafeTranslator()

Method Summary

Modifier and Type	Method	Description
P	load(com.google.cloud.datastore.Value<D> node, LoadContext ctx, Path path)	Loads the content of the specified datastore node, returning the pojo equivalent.
protected abstract P	loadSafe(com.google.cloud.datastore.Value<D> node, LoadContext ctx, Path path)	Implement this, returning a proper translated value
com.google.cloud.datastore.Value<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.
protected abstract com.google.cloud.datastore.Value<D>	saveSafe(P pojo, boolean index, SaveContext ctx, Path path)	Implement this, returning a proper translated value

Methods inherited from class java.lang.Object

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

Constructor Detail

NullSafeTranslator

public NullSafeTranslator()

Method Detail

load

public final P load(com.google.cloud.datastore.Value<D> node,
                    LoadContext ctx,
                    Path path)
             throws SkipException

Description copied from interface: Translator

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.

Specified by:

load in interface Translator<P,D>

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

public final com.google.cloud.datastore.Value<D> save(P pojo,
                                                      boolean index,
                                                      SaveContext ctx,
                                                      Path path)
                                               throws SkipException

Description copied from interface: Translator

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

Specified by:

save in interface Translator<P,D>

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

loadSafe

protected abstract P loadSafe(com.google.cloud.datastore.Value<D> node,
                              LoadContext ctx,
                              Path path)
                       throws SkipException

Implement this, returning a proper translated value

Parameters:

node - will never be null or NullValue

Throws:

SkipException

saveSafe

protected abstract com.google.cloud.datastore.Value<D> saveSafe(P pojo,
                                                                boolean index,
                                                                SaveContext ctx,
                                                                Path path)
                                                         throws SkipException

Implement this, returning a proper translated value

Parameters:

pojo - will never be null

Throws:

SkipException