Class Entity (2.0.0)

public final class Entity extends PropertyContainer implements Cloneable

Entity is the fundamental unit of data storage. It has an immutable identifier (contained in the Key) object, a reference to an optional parent Entity, a kind (represented as an arbitrary string), and a set of zero or more typed properties.

Inheritance

java.lang.Object > PropertyContainer > Entity

Implements

Cloneable

Inherited Members

PropertyContainer.appendPropertiesTo(StringBuilder)

PropertyContainer.clone()

PropertyContainer.getProperties()

PropertyContainer.getProperty(String)

PropertyContainer.hasProperty(String)

PropertyContainer.isUnindexedProperty(String)

PropertyContainer.removeProperty(String)

PropertyContainer.setIndexedProperty(String,Object)

PropertyContainer.setPropertiesFrom(PropertyContainer)

PropertyContainer.setProperty(String,@Nullable Object)

PropertyContainer.setUnindexedProperty(String,Object)

Object.equals(Object)

Object.finalize()

Object.getClass()

Object.hashCode()

Object.notify()

Object.notifyAll()

Object.toString()

Object.wait()

Object.wait(long)

Object.wait(long,int)

Static Fields

KEY_RESERVED_PROPERTY

public static final String KEY_RESERVED_PROPERTY

A reserved property name used to refer to the key of the entity. This string can be used for filtering and sorting by the entity key itself.

Field Value
Type	Description
String

SCATTER_RESERVED_PROPERTY

public static final String SCATTER_RESERVED_PROPERTY

A reserved property name used to refer to the scatter property of the entity. Used for finding split points (e.g. for mapping over a kind).

Field Value
Type	Description
String

VERSION_RESERVED_PROPERTY

public static final String VERSION_RESERVED_PROPERTY

A reserved property name used to report an entity group's version.

Field Value
Type	Description
String

Constructors

Entity(Key key)

public Entity(Key key)

Create a new Entity uniquely identified by the provided Key. Creating an entity for the purpose of insertion (as opposed to update) with a key that has its id field set is strongly discouraged unless the key was returned by a KeyRange. See Also: KeyRange

Parameter
Name	Description
key	Key

Entity(String kind)

public Entity(String kind)

Create a new Entity with the specified kind and no parent Entity. The instantiated Entity will have an incomplete Key when this constructor returns. The Key will remain incomplete until you put the Entity, after which time the Key will have its id set.

Parameter
Name	Description
kind	String

Entity(String kind, @Nullable Key parent)

public Entity(String kind, @Nullable Key parent)

Create a new Entity with the specified kind and parent Entity. The instantiated Entity will have an incomplete Key when this constructor returns. The Key will remain incomplete until you put the Entity, after which time the Key will have its id set.

Parameters
Name	Description
kind	String
parent	@org.checkerframework.checker.nullness.qual.Nullable com.google.appengine.api.datastore.Key

Entity(String kind, String keyName)

public Entity(String kind, String keyName)

Create a new Entity with the specified kind and key name and no parent Entity. The instantiated Entity will have a complete Key when this constructor returns. The Key's name field will be set to the value of keyName.

This constructor is syntactic sugar for new Entity(KeyFactory.createKey(kind, keyName)).

Parameters
Name	Description
kind	String
keyName	String

Entity(String kind, String keyName, Key parent)

public Entity(String kind, String keyName, Key parent)

Create a new Entity with the specified kind, key name, and parent Entity. The instantiated Entity will have a complete Key when this constructor returns. The Key's name field will be set to the value of keyName.

This constructor is syntactic sugar for new Entity(KeyFactory.createKey(parent, kind, keyName)).

Parameters
Name	Description
kind	String
keyName	String
parent	Key

Entity(String kind, long id)

public Entity(String kind, long id)

Create a new Entity with the specified kind and ID and no parent Entity. The instantiated Entity will have a complete Key when this constructor returns. The Key's id field will be set to the value of id.

Creating an entity for the purpose of insertion (as opposed to update) with this constructor is discouraged unless the id was obtained from a key returned by a KeyRange obtained from AsyncDatastoreService#allocateIds(String, long) or DatastoreService#allocateIds(String, long) for the same kind.

This constructor is syntactic sugar for new Entity(KeyFactory.createKey(kind, id)).

Parameters
Name	Description
kind	String
id	long

Entity(String kind, long id, Key parent)

public Entity(String kind, long id, Key parent)

Create a new Entity with the specified kind and ID and parent Entity. The instantiated Entity will have a complete Key when this constructor returns. The Key's id field will be set to the value of id.

Creating an entity for the purpose of insertion (as opposed to update) with this constructor is discouraged unless the id was obtained from a key returned by a KeyRange obtained from AsyncDatastoreService#allocateIds(Key, String, long) or DatastoreService#allocateIds(Key, String, long) for the same parent and kind.

This constructor is syntactic sugar for new Entity(KeyFactory.createKey(parent, kind, id)).

Parameters
Name	Description
kind	String
id	long
parent	Key

Methods

clone()

public Entity clone()

Returns a shallow copy of this Entity instance. Collection properties are cloned as an ArrayList, the type returned from the datastore. Instances of mutable datastore types are cloned as well. Instances of all other types are reused.

Returns
Type	Description
Entity	a shallow copy of this Entity

Overrides

PropertyContainer.clone()

equals(@Nullable Object object)

public boolean equals(@Nullable Object object)

Two Entity objects are considered equal if they refer to the same entity (i.e. their Key objects match).

Parameter
Name	Description
object	@org.checkerframework.checker.nullness.qual.Nullable java.lang.Object

Returns
Type	Description
boolean

Overrides

Object.equals(Object)

getAppId()

public String getAppId()

Returns the identifier of the application that owns this Entity. This is simply a convenience method that forwards to the Key for this Entity.

Returns
Type	Description
String

getKey()

public Key getKey()

Returns the Key that represents this Entity. If the entity has not yet been saved (e.g. via DatastoreService.put), this Key will not be fully specified and cannot be used for certain operations (like DatastoreService.get). Once the Entity has been saved, its Key will be updated to be fully specified.

Returns
Type	Description
Key

getKind()

public String getKind()

Returns a logical type that is associated with this Entity. This is simply a convenience method that forwards to the Key for this Entity.

Returns
Type	Description
String

getNamespace()

public String getNamespace()

Returns the namespace of the application/namespace that owns this Entity. This is simply a convenience method that forwards to the Key for this Entity.

Returns
Type	Description
String

getParent()

public @Nullable Key getParent()

Get a Key that corresponds to this the parent Entity of this Entity. This is simply a convenience method that forwards to the Key for this Entity.

Returns
Type	Description
@org.checkerframework.checker.nullness.qual.Nullable com.google.appengine.api.datastore.Key

hashCode()

public int hashCode()

Returns
Type	Description
int

Overrides

Object.hashCode()

setPropertiesFrom(Entity src)

public void setPropertiesFrom(Entity src)

Parameter
Name	Description
src	Entity

toString()

public String toString()

Returns
Type	Description
String

Overrides

Object.toString()