See: Description
Interface | Description |
---|---|
AsyncDatastoreService |
An asynchronous version of
DatastoreService . |
BaseDatastoreService |
Methods that are common between
DatastoreService and
AsyncDatastoreService . |
CallbackContext<T> |
Describes the context in which a callback runs.
|
DatastoreConfig | Deprecated
Use
DatastoreServiceConfig instead. |
DatastoreService |
The
DatastoreService provides synchronous access to a schema-less
data storage system. |
IDatastoreServiceFactory |
This interface should be implemented by providers of the
DatastoreService and registered
with com.google.appengine.spi.ServiceFactoryFactory . |
PreparedQuery |
Contains methods for fetching and returning entities
from a
Query . |
QueryResultIterable<T> |
A class that produces
QueryResultIterator s. |
QueryResultIterator<T> |
A class that iterates through the results of a
Query |
QueryResultList<T> |
A list of results returned by executing a
Query . |
Transaction |
Describes a logical unit of work to be performed against the datastore.
|
Class | Description |
---|---|
AdminDatastoreService |
An AsyncDatastoreService implementation that is pinned to a specific appId and namesapce.
|
AdminDatastoreService.EntityBuilder | |
AdminDatastoreService.KeyBuilder | |
AdminDatastoreService.QueryBuilder | |
Blob |
Blob contains an array of bytes. |
Category |
A tag, ie a descriptive word or phrase.
|
CompositeIndexManager |
Composite index management operations needed by the datastore api.
|
CompositeIndexUtils |
Static utilities for working with composite indexes.
|
Cursor |
A cursor that represents a position in a query.
|
DatastoreApiHelper |
Helper methods and constants shared by classes that implement the Java api
on top of the datastore.
|
DatastoreAttributes |
Attributes of a datastore.
|
DatastoreServiceConfig |
User-configurable properties of the datastore.
|
DatastoreServiceConfig.Builder |
Contains static creation methods for
DatastoreServiceConfig . |
DatastoreServiceFactory |
Creates DatastoreService implementations.
|
DataTypeTranslator |
DataTypeTranslator is a utility class for converting
between the data store's Property protocol buffers and the
user-facing classes (String , User , etc.). |
DataTypeTranslator.ComparableByteArray |
A wrapper for a
byte[] that implements Comparable . |
DataTypeUtils |
DataTypeUtils presents a simpler interface that allows
user-code to determine what Classes can safely be stored as
properties in the data store. |
DeleteContext |
Concrete
CallbackContext implementation that is specific to
delete() callbacks. |
An e-mail address datatype.
|
|
EmbeddedEntity |
A property value containing embedded entity properties (and optionally a
Key ). |
Entities |
Utility functions and constants for entities.
|
Entity |
Entity is the fundamental unit of data storage. |
EntityProtoComparators |
Utilities for comparing
EntityProto . |
EntityProtoComparators.EntityProtoComparator |
A comparator for
com.google.storage.onestore.v3.OnestoreEntity.EntityProto
objects with the same ordering as EntityComparator . |
EntityTranslator |
EntityTranslator contains the logic to translate an Entity into the protocol buffers that are used to pass it to the
implementation of the API. |
ExtendableEntityUtil |
Internal class that provides utility methods for
ExtendableEntity objects. |
FetchOptions |
Describes the limit, offset, and chunk size to be applied when
executing a
PreparedQuery . |
FetchOptions.Builder |
Contains static creation methods for
FetchOptions . |
FutureHelper |
Utilities for working with
Futures in the synchronous
datastore api. |
GeoPt |
A geographical point, specified by float latitude and longitude
coordinates.
|
IDatastoreServiceFactoryProvider |
Creates
IDatastoreServiceFactory implementations. |
IMHandle |
An instant messaging handle.
|
Index |
A Datastore
Index definition. |
Index.Property |
An indexed property.
|
IndexTranslator |
Helper class to translate between
Index to com.google.storage.onestore.v3.OnestoreEntity.Index . |
Key |
The primary key for a datastore entity.
|
KeyFactory |
This class enables direct creation of
Key objects, both in
the root entity group (no parent) and as the child of a given
parent. |
KeyFactory.Builder |
Helper class that aids in the construction of
Keys with
ancestors. |
KeyRange |
Represents a range of unique datastore identifiers from
getStart().getId() to getEnd().getId() inclusive. |
Link |
A
Link is a URL of limited length. |
PhoneNumber |
A human-readable phone number.
|
PostalAddress |
A human-readable mailing address.
|
PostLoadContext |
Concrete
CallbackContext implementation that is specific to
intercepted operations that load Entities , currently get
and "query". |
PreGetContext |
Concrete
CallbackContext implementation that is specific to
intercepted get() operations. |
PreQueryContext |
Concrete
CallbackContext implementation that is specific to
intercepted queries. |
Projection |
A query projection.
|
PropertyContainer |
A mutable property container.
|
PropertyProjection |
A property projection.
|
PutContext |
Concrete
CallbackContext implementation that is specific to
put() callbacks. |
Query | |
Query.CompositeFilter |
A
Query.Filter that combines several sub filters using a Query.CompositeFilterOperator . |
Query.Filter |
The base class for a query filter.
|
Query.FilterPredicate |
A
Query.Filter on a single property. |
Query.GeoRegion |
A geographic region intended for use in a
Query.StContainsFilter . |
Query.GeoRegion.Circle |
A geographical region representing all points within a fixed
distance from a central point, i.e., a circle.
|
Query.GeoRegion.Rectangle |
A simple geographical region bounded by two latitude lines, and two
longitude lines, i.e., a "rectangle".
|
Query.SortPredicate |
SortPredicate is a data container that holds a single sort
predicate.
|
Query.StContainsFilter |
A
Query.Filter representing a geo-region containment predicate. |
Rating |
A user-provided integer rating for a piece of content.
|
RawValue |
A raw datastore value.
|
ReadPolicy |
Policy for reads.
|
ShortBlob |
ShortBlob contains an array of bytes no longer than
DataTypeUtils.MAX_SHORT_BLOB_PROPERTY_LENGTH . |
Text |
Text wraps around a string of unlimited size. |
TransactionHelper |
TransactionHelper enables the task queue API to serialize a datastore transaction
without knowing the details of how it is implemented. |
TransactionOptions |
Describes options for transactions, passed at transaction creation time.
|
TransactionOptions.Builder |
Contains static creation methods for
TransactionOptions . |
Enum | Description |
---|---|
DatastoreAttributes.DatastoreType |
Indicates the type of datastore being used.
|
DatastoreService.KeyRangeState |
Indicates the state of a
KeyRange . |
IMHandle.Scheme |
Supported IM schemes.
|
ImplicitTransactionManagementPolicy |
Describes the various policies the datastore can follow for implicit
transaction management.
|
Index.IndexState |
Indicates the state of the
Index . |
Query.CompositeFilterOperator |
Operators supported by
Query.CompositeFilter . |
Query.FilterOperator |
Operators supported by
Query.FilterPredicate . |
Query.SortDirection |
SortDirection controls the order of a sort.
|
ReadPolicy.Consistency |
Setting the
Consistency for reads allows you to decide whether
freshness or availability is more important. |
Exception | Description |
---|---|
CommittedButStillApplyingException |
CommittedButStillApplyingException is thrown when the write or
transaction was committed, but some entities or index rows may not have
been fully updated. |
DatastoreFailureException |
DatastoreFailureException is thrown when any unknown
error occurs while communicating with the data store. |
DatastoreNeedIndexException |
DatastoreNeedIndexException is thrown when no matching index was
found for a query requiring an index. |
DatastoreTimeoutException |
DatastoreTimeoutException is thrown when a datastore operation
times out. |
EntityNotFoundException |
EntityNotFoundException is thrown when no Entity
with the specified Key could be found. |
PreparedQuery.TooManyResultsException |
Indicates that too many results were found for
PreparedQuery.asSingleEntity() . |
Annotation Type | Description |
---|---|
PostDelete |
Identifies a callback method to be invoked after an
Entity of any of
the specified kinds is deleted from the datastore. |
PostLoad |
Identifies a callback method to be invoked after an
Entity of any of
the specified kinds is loaded from the datastore. |
PostPut |
Identifies a callback method to be invoked after an
Entity of any of
the specified kinds is written to the datastore. |
PreDelete |
Identifies a callback method to be invoked before an
Entity of any
of the specified kinds is deleted from the datastore. |
PreGet |
Identifies a callback method to be invoked before an
Entity of any
of the specified kinds is fetched from the datastore via a get() rpc. |
PrePut |
Identifies a callback method to be invoked before an
Entity of any
of the specified kinds is written to the datastore. |
PreQuery |
Identifies a callback method to be invoked before a
Query for any
of the specified kinds is executed against the datastore. |
A common pattern of usage is:
// Get a handle on the datastore itself DatastoreService datastore = DatastoreServiceFactory.getDatastoreService(); // Lookup data by known key name Entity userEntity = datastore.get(KeyFactory.createKey("UserInfo", email)); // Or perform a query Query query = new Query("Task"); query.addFilter("dueDate", Query.FilterOperator.LESS_THAN, today); for (Entity taskEntity : datastore.prepare(query).asIterable()) { if ("done".equals(taskEntity.getProperty("status"))) { datastore.delete(taskEntity); } else { taskEntity.setProperty("status", "overdue"); datastore.put(taskEntity); } }
This illustrates several basic points:
DatastoreService
object,
produced from a DatastoreServiceFactory
.
Entity
object, which are of named kinds ("UserInfo" and "Task" above).
Key
value,
which can be created by a KeyFactory
to retrieve a specific known entity. If the key is not readily
determined, then Query
objects can be used to retrieve one Entity, multiple as a list, Iterable
, or Iterator
, or to retrieve the
count of matching entities.
Query
in the snippet above searches
only for Task entities associated with a specific UserInfo entity, and
then filters those for Tasks due before today.
In production, non-trivial queries cannot be performed until one
or more indexes have been built to ensure that the individual
queries can be processed efficiently. You can specify the set of
indexes your application requires in a
WEB-INF/datastore-indexes.xml
file, or they can be
generated automatically as you test your application in the
Development Server. If a query requires an index that cannot be
found, a DatastoreNeedIndexException
will be thrown at runtime.
Although Google App Engine allows many versions of your application to be accessible, there is only one datastore for your application, shared by all versions. Similarly, the set of indexes is shared by all application versions.
Application authors may also consider using either of the provided JDO or JPA interfaces to the datastore.