Objectify (Objectify App Engine 6.0 API)

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 and 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. 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.
`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.
`void`	`execute(TxnType txnType, Runnable work)` Exactly the same behavior as the Work version, but doesn't return anything.
`<R> R`	`execute(TxnType txnType, Work<R> work)` Executes the work with the transactional behavior defined by the parameter txnType.
`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.
`Saver`	`save()` Start a save command chain.
`void`	`transact(Runnable work)` Exactly the same behavior as the Work version, but doesn't return anything.
`<R> R`	`transact(Work<R> work)` Executes work in a transaction.
`Objectify`	`transactionless()` Deprecated. This method has very poorly defined behavior and will be removed SOON. Instead you should use the `transactionless(Work)` method.
`void`	`transactionless(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`	`transactNew(int limitTries, 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(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.

- 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.
  - 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
```
@Deprecated
Objectify transactionless()
```
    Deprecated. This method has very poorly defined behavior and will be removed SOON. Instead you should use the transactionless(Work) method.
  - 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.

Interface Objectify

Method Summary

Method Detail

load

save

delete

defer

factory

deadline

cache

mandatoryTransactions

getTransaction

transactionless

transactionless

transactionless

transact

transact

transactNew

transactNew

transactNew

transactNew

execute

execute

flush

clear

isLoaded