GAEでサポートされないJDO/JPAの機能

java gae

メモ。

だらだら備忘録: Using JDO with App Engine

Unsupported Features of JDO

The following features of the JDO interface are not supported by the App Engine implementation:

  • Unowned relationships. You can implement unowned relationships using explicit Key values. JDO's syntax for unowned relationships may be supported in a future release.
  • Owned many-to-many relationships.
  • contains() syntax for query filters on Collection fields. You can test that a multi-valued property (a Collection field) has a value using an equality filter: collection == "value"
  • "Join" queries. You cannot use a field of a child entity in a filter when performing a query on the parent kind. Note that you can test the parent's relationship field directly in query using a key.
  • JDOQL grouping and other aggregate queries.
  • Polymorphic queries. You cannot perform a query of a class to get instances of a subclass. Each class is represented by a separate entity kind in the datastore.
  • IdentityType.DATASTORE for the @PersistenceCapable annotation. Only IdentityType.APPLICATION is supported.
  • There is currently a bug preventing preventing persistent fields on superclasses from being saved to the datastore. This will be fixed in a future release.

Google App Engine で JPA使えるんですね - tokuryoのJavaEE5日記

# Owned many-to-many relationships, and unowned relationships. You can implement unowned relationships using explicit Key values, though type checking is not enforced in the API.

# "Join" queries. You cannot use a field of a child entity in a filter when performing a query on the parent kind. Note that you can test the parent's relationship field directly in query using a key.

# Aggregation queries (group by, having, sum, avg, max, min)

# Polymorphic queries. You cannot perform a query of a class to get instances of a subclass. Each class is represented by a separate entity kind in the datastore.