public final class Entities
extends java.lang.Object
Modifier and Type | Field and Description |
---|---|
static long
|
ENTITY_GROUP_METADATA_ID
ID for __entity_group__ entities.
|
static java.lang.String
|
ENTITY_GROUP_METADATA_KIND
A metadata kind that can be used to get information about entity groups.
|
static java.lang.String
|
KIND_METADATA_KIND
A metadata kind that can be used to query for kinds that exist in the
datastore.
|
static long
|
NAMESPACE_METADATA_EMPTY_ID
The numeric ID for __namespace__ keys representing the empty namespace.
|
static java.lang.String
|
NAMESPACE_METADATA_KIND
A metadata kind that can be used to query for namespaces that exist in the
datastore.
|
static java.lang.String
|
PROPERTY_METADATA_KIND
A metadata kind that can be used to query for properties that exist in the
datastore.
|
Constructor and Description |
---|
Entities
()
|
Modifier and Type | Method and Description |
---|---|
static
Key
|
createEntityGroupKey
(
Key
key)
Create an __entity_group__ key for the entity group containing
key
.
|
static
Key
|
createKindKey
(java.lang.String kind)
Create a __kind__ key for
kind
.
|
static
Key
|
createNamespaceKey
(java.lang.String namespace)
Create a __namespace__ key for
namespace
.
|
static
Key
|
createPropertyKey
(java.lang.String kind,
java.lang.String property)
Create a __property__ key for
property
of
kind
.
|
static java.lang.String
|
getNamespaceFromNamespaceKey
(
Key
namespaceKey)
Extract the namespace name from a __namespace__ key.
|
static long
|
getVersionProperty
(
Entity
entity)
Get the value of the __version__ property from
entity
.
|
public static final java.lang.String KIND_METADATA_KIND
public static final java.lang.String PROPERTY_METADATA_KIND
public static final java.lang.String NAMESPACE_METADATA_KIND
public static final long NAMESPACE_METADATA_EMPTY_ID
public static final java.lang.String ENTITY_GROUP_METADATA_KIND
DatastoreService.get(com.google.appengine.api.datastore.Key)
call on key
KeyFactory.createKey(R, ENTITY_GROUP_METADATA_KIND,
ENTITY_GROUP_METADATA_ID)
.
The resulting entity has a
Entity.VERSION_RESERVED_PROPERTY
numeric property whose value is guaranteed to increase on every change to
the entity group. This value may also occasionally increase without any
user-visible change to the entity group.
public static final long ENTITY_GROUP_METADATA_ID
ENTITY_GROUP_METADATA_KIND
,
Constant Field Values
public static Key createKindKey(java.lang.String kind)
kind
.
kind
- Kind to create key for.
public static Key createPropertyKey(java.lang.String kind, java.lang.String property)
property
of
kind
.
kind
- Kind to create key for.
property
- Property to create key for.
public static Key createNamespaceKey(java.lang.String namespace)
namespace
.
namespace
- Namespace to create key for.
public static java.lang.String getNamespaceFromNamespaceKey(Key namespaceKey)
namespaceKey
- Key to extract namespace from.
public static Key createEntityGroupKey(Key key)
key
.
key
- Key of any entity in the entity group.
public static long getVersionProperty(Entity entity)
entity
.
entity
- Entity to fetch __version__ from (must have a numeric
__version__ property).