public class EntityTranslator extends Object implements Translator<Object,com.google.appengine.api.datastore.PropertyContainer>
Translator which can translate arbitrary entities based on registered kinds. This provides a layer of indirection, and allows you to store heterogeneous collections.
Constructor and Description |
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EntityTranslator(Registrar registrar) |
Modifier and Type | Method and Description |
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Object |
load(com.google.appengine.api.datastore.PropertyContainer container,
LoadContext ctx,
Path path)
Loads the content of the specified datastore node, returning the pojo equivalent.
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com.google.appengine.api.datastore.PropertyContainer |
save(Object pojo,
boolean index,
SaveContext ctx,
Path path)
Translates a pojo (or some component thereof) into a format suitable for storage in the datastore.
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public EntityTranslator(Registrar registrar)
public Object load(com.google.appengine.api.datastore.PropertyContainer container, LoadContext ctx, Path path) throws SkipException
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.
load
in interface Translator<Object,com.google.appengine.api.datastore.PropertyContainer>
container
- 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 translatorSkipException
- if the return value should be abandoned.LoadEngine
public com.google.appengine.api.datastore.PropertyContainer save(Object pojo, boolean index, SaveContext ctx, Path path) throws SkipException
Translator
save
in interface Translator<Object,com.google.appengine.api.datastore.PropertyContainer>
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 valuespath
- 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).SkipException
- if the return value should be abandonedCopyright © 2016. All rights reserved.