Package com.googlecode.objectify

Interface Objectify

  • All Known Implementing Classes:
    ObjectifyImpl
    public interface Objectify

    This is the main "business end" of Objectify. It lets you load, save, and delete your typed POJO entities.

    Objectify instances are obtained by calling the static method ObjectifyService.ofy(). This method will always provide the correct Objectify instance for a given transactional context. You can run transactions by calling Objectify.transact() or Objectify.transactNew(); calling ObjectifyService.ofy() within Work.run() will produce the correct Objectify instance associated with the correct transaction.

    Objectify instances are immutable but they are NOT thread-safe. The instance contains a session cache of entities that have been loaded from the instance. You should never access an Objectify from more than one thread simultaneously.

    Author:
    Jeff Schnitzer

    • Method Summary

      All Methods Instance Methods Abstract Methods Deprecated Methods 
      Modifier and Type Method Description
      Objectify cache​(boolean value)
      Provides a new Objectify instance which uses (or doesn't use) a 2nd-level memcache.
      void clear()
      Clears the session; all subsequent requests (or Ref.get() calls) will go to the datastore/memcache to repopulate the session.
      Objectify deadline​(Double value)
      Deprecated.
      This no longer does anything.
      Deferred defer()
      Start a deferred command chain, which lets you make multiple save or delete calls on a single entity without incurring multiple datastore operations.
      Deleter delete()
      Start a delete command chain.
      <R> R execute​(TxnType txnType, Work<R> work)
      Executes the work with the transactional behavior defined by the parameter txnType.
      void execute​(TxnType txnType, Runnable work)
      Exactly the same behavior as the Work version, but doesn't return anything.
      ObjectifyFactory factory()
      Obtain the ObjectifyFactory from which this Objectify instance was created.
      void flush()
      Synchronously flushes any deferred operations to the datastore.
      AsyncTransaction getTransaction()
      This used to have meaning in the old GAE SDK but no longer does.
      boolean isLoaded​(Key<?> key)  
      Loader load()
      Start a load command chain.
      Objectify mandatoryTransactions​(boolean value)
      Provides a new Objectify instance which throws an exception whenever save() or delete() is called from outside a transaction context.
      Objectify namespace​(String namespace)
      Explicitly sets the namespace for keys generated in load, save, delete operations.
      Saver save()
      Start a save command chain.
      <R> R transact​(Work<R> work)
      Executes work in a transaction.
      void transact​(Runnable work)
      Exactly the same behavior as the Work version, but doesn't return anything.
      <R> R transactionless​(Work<R> work)
      Executes work outside of a transaction.
      void transactionless​(Runnable work)
      Exactly the same behavior as the Work version, but doesn't return anything.
      <R> R transactNew​(int limitTries, Work<R> work)
      Executes the work in a new transaction, repeating up to limitTries times when a ConcurrentModificationException is thrown.
      void transactNew​(int limitTries, Runnable work)
      Exactly the same behavior as the Work version, but doesn't return anything.
      <R> R transactNew​(Work<R> work)
      Executes work in a new transaction.
      void transactNew​(Runnable work)
      Exactly the same behavior as the Work version, but doesn't return anything.

    • Method Detail

      • load

        Loader load()

        Start a load command chain. This is where you begin for any request that fetches data from the datastore: gets and queries.

        A quick example: Map<Key<Thing>, Thing> things = ofy().load().type(Thing.class).parent(par).ids(123L, 456L);

        All command objects are immutable; this method returns a new object rather than modifying the current command object.

        Returns:
        the next step in the immutable command chain.

      • save

        Saver save()

        Start a save command chain. Allows you to save (or re-save) entity objects. Note that all command chain objects are immutable.

        Saves do NOT cascade; if you wish to save an object graph, you must save each individual entity.

        A quick example: ofy().save().entities(e1, e2, e3).now();

        All command objects are immutable; this method returns a new object rather than modifying the current command object.

        Returns:
        the next step in the immutable command chain.

      • delete

        Deleter delete()

        Start a delete command chain. Lets you delete entities or keys.

        Deletes do NOT cascade; if you wish to delete an object graph, you must delete each individual entity.

        A quick example: ofy().delete().entities(e1, e2, e3).now();

        All command objects are immutable; this method returns a new object rather than modifying the current command object.

        Returns:
        the next step in the immutable command chain.

      • defer

        Deferred defer()

        Start a deferred command chain, which lets you make multiple save or delete calls on a single entity without incurring multiple datastore operations. Deferred operations are executed at the end of a unit-of-work (transaction, or http request if not in a transaction).

        Deferred operations are reflected in the session cache immediately. However query operations may not reflect these changes. For example, newly indexed entities may not show up, even with an otherwise strongly consistent ancestor query. This should not be surprising since the actual save operation has not occurred yet.

        In the case of deferred save() and delete() operations on the same entity, the last one wins.

        Returns:
        the next step in the immutable command chain.

      • factory

        ObjectifyFactory factory()
        Obtain the ObjectifyFactory from which this Objectify instance was created.
        Returns:
        the ObjectifyFactory associated with this Objectify instance.

      • namespace

        Objectify namespace​(String namespace)

        Explicitly sets the namespace for keys generated in load, save, delete operations.

        This overrides the setting of NamespaceManager.set().

        Note that this only affects implicitly created keys; if you pass key objects into load or delete methods, the namespace contained in the key will be used.

             final Key<Foo> key = Key.create(Foo.class, 123);
     ofy().namespace("blah").load().key(key);  // namespace() has no effect! The key already has the default namespace.
     ofy().namespace("blah").load().type(Foo.class).id(123);    // namespace() works as expected

        All command objects are immutable; this method returns a new object instead of modifying the current command object.

        Parameters:
        namespace - is the namespace to pick; "" (empty string) forces the datastore default namespace; null restores the check for NamespaceManager.set()
        Returns:
        the next step in the immutable command chain, which allows you to start an operation.

      • deadline

        @Deprecated
Objectify deadline​(Double value)
        Deprecated.
        This no longer does anything. Transport-level behavior is set via DatastoreOptions when you create the ObjectifyFactory. Altering this would require tearing down and re-establishing connections, which will have a negative performance impact. For better or worse, deadline is now a global setting.

        Provides a new Objectify instance with a limit, in seconds, for datastore calls. If datastore calls take longer than this amount, a timeout exception will be thrown.

        The new instance will inherit all other characteristics (transaction, cache policy, session cache contents, etc) from this instance.

        All command objects are immutable; this method returns a new object rather than modifying the current command object.

        Parameters:
        value - - limit in seconds, or null to indicate no deadline (other than the standard whole request deadline of 30s/10m).
        Returns:
        a new immutable Objectify instance with the specified deadline

      • cache

        Objectify cache​(boolean value)

        Provides a new Objectify instance which uses (or doesn't use) a 2nd-level memcache. If true, Objectify will obey the @Cache annotation on entity classes, saving entity data to the GAE memcache service. Fetches from the datastore for @Cache entities will look in the memcache service first. This cache is shared across all versions of your application across the entire GAE cluster.

        Objectify instances are cache(true) by default.

        All command objects are immutable; this method returns a new object rather than modifying the current command object.

        Returns:
        a new immutable Objectify instance which will (or won't) use the global cache

      • mandatoryTransactions

        Objectify mandatoryTransactions​(boolean value)

        Provides a new Objectify instance which throws an exception whenever save() or delete() is called from outside a transaction context. This is a reasonable sanity check for most business workloads; you may wish to enable it globally by overriding ObjectifyFactory.begin() to twiddle this flag on the returned object.

        Objectify instances are mandatoryTransactions(false) by default.

        All command objects are immutable; this method returns a new object rather than modifying the current command object.

        Returns:
        a new immutable Objectify instance which will (or won't) require transactions for save() and delete().

      • getTransaction

        AsyncTransaction getTransaction()

        This used to have meaning in the old GAE SDK but no longer does. Right now this is pretty much only useful as a null test to see if you are currently in a transaction. This method will probably be removed.

      • transactionless

        <R> R transactionless​(Work<R> work)

        Executes work outside of a transaction. This is a way to "escape" from a transaction and perform datastore operations that would otherwise not be allowed (or perhaps to load data without hitting entity group limits). If there is not already a transaction running, the work is executed normally. If there is not already a transaction context, a new transaction will be started.

        For example, to return an entity fetched outside of a transaction: Thing th = ofy().transactionless(() -> ofy().load().key(thingKey).now())

        Parameters:
        work - defines the work to be done outside of a transaction
        Returns:
        the result of the work

      • transactionless

        void transactionless​(Runnable work)

        Exactly the same behavior as the Work version, but doesn't return anything. Convenient for Java8 so you don't have to return something from the lambda.

      • transact

        <R> R transact​(Work<R> work)

        Executes work in a transaction. If there is already a transaction context, that context will be inherited. If there is not already a transaction context, a new transaction will be started.

        Within Work.run(), obtain the correct transactional Objectify instance by calling ObjectifyService.ofy()

        ConcurrentModificationExceptions will cause the transaction to repeat as many times as necessary to finish the job. Work MUST idempotent.

        Parameters:
        work - defines the work to be done in a transaction. If this method started a new transaction, it will be committed when work is complete. If transactional context was inherited, no commit is issued until the full transaction completes normally.
        Returns:
        the result of the work

      • transact

        void transact​(Runnable work)

        Exactly the same behavior as the Work version, but doesn't return anything. Convenient for Java8 so you don't have to return something from the lambda.

      • transactNew

        <R> R transactNew​(Work<R> work)

        Executes work in a new transaction. Note that this is equivalent to transactNew(Integer.MAX_VALUE, work);

        ConcurrentModificationExceptions will cause the transaction to repeat as many times as necessary to finish the job. Work MUST idempotent.

        Within Work.run(), obtain the new transactional Objectify instance by calling ObjectifyService.ofy()

        Parameters:
        work - defines the work to be done in a transaction. After the method exits, the transaction will commit.
        Returns:
        the result of the work

      • transactNew

        void transactNew​(Runnable work)

        Exactly the same behavior as the Work version, but doesn't return anything. Convenient for Java8 so you don't have to return something from the lambda.

      • transactNew

        <R> R transactNew​(int limitTries,
                  Work<R> work)

        Executes the work in a new transaction, repeating up to limitTries times when a ConcurrentModificationException is thrown. This requires your Work to be idempotent; otherwise limit tries to 1.

        Within Work.run(), obtain the new transactional Objectify instance by calling ObjectifyService.ofy()

        Parameters:
        limitTries - is the max # of tries. Must be > 0. A value of 1 means "try only once".
        work - defines the work to be done in a transaction. After the method exits, the transaction will commit.
        Returns:
        the result of the work

      • transactNew

        void transactNew​(int limitTries,
                 Runnable work)

        Exactly the same behavior as the Work version, but doesn't return anything. Convenient for Java8 so you don't have to return something from the lambda.

      • execute

        <R> R execute​(TxnType txnType,
              Work<R> work)

        Executes the work with the transactional behavior defined by the parameter txnType. This is very similar to EJB semantics. The work can inherit a transaction, create a new transaction, prevent transactions, etc.

        This method principally exists to facilitate implementation of AOP interceptors that provide EJB-like behavior. Usually you will call transact() or transactNew() when writing code.

        Note that ConcurrentModificationExceptions will cause the transaction to repeat as many times as necessary to finish the job. Work MUST idempotent.

        Within Work.run(), obtain the correct Objectify instance by calling ObjectifyService.ofy()

        Parameters:
        txnType - defines what kind of transaction context the work should be executed in.
        work - defines the work to be done; possibly in a transaction, possibly not as defined by txnType
        Returns:
        the result of the work

      • execute

        void execute​(TxnType txnType,
             Runnable work)

        Exactly the same behavior as the Work version, but doesn't return anything. Convenient for Java8 so you don't have to return something from the lambda.

      • flush

        void flush()
        Synchronously flushes any deferred operations to the datastore. Objectify does this for you at the end of transactions and requests, but if you need data to be written immediately - say, you're about to perform a strongly-consistent ancestor query and you need to see the updated indexes immediately - you can call this method. If there are no deferred operations, this does nothing.

      • clear

        void clear()

        Clears the session; all subsequent requests (or Ref.get() calls) will go to the datastore/memcache to repopulate the session. This should rarely, if ever be necessary. Note that if you iterate query results you should only perform this action on chunk boundaries, otherwise performance will suffer. This is a "use only if you really know what you are doing" feature.

      • isLoaded

        boolean isLoaded​(Key<?> key)
        Returns:
        true if the key has been loaded into the session; false if loading the key would result in a datastore (or memcache) fetch.