Package 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

    Modifier and Type
    Method
    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 Details

    • 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