org.janusgraph.core

Interface JanusGraphElement

All Superinterfaces:

org.apache.tinkerpop.gremlin.structure.Element, Idfiable, Removable

All Known Subinterfaces:

EdgeLabel, InternalElement, InternalRelation, InternalRelationType, InternalVertex, InternalVertexLabel, JanusGraphEdge, JanusGraphRelation, JanusGraphVertex, JanusGraphVertexProperty<V>, PropertyKey, RelationType, StandardRelation, SystemRelationType, VertexLabel

All Known Implementing Classes:

AbstractEdge, AbstractElement, AbstractTypedRelation, AbstractVertex, AbstractVertexProperty, BaseKey, BaseLabel, BaseRelationType, BaseVertexLabel, CacheEdge, CacheVertex, CacheVertexProperty, EdgeLabelVertex, EmptyJanusGraphVertexProperty, EmptyRelationType, EmptyVertex, FulgoraVertexProperty, ImplicitKey, JanusGraphSchemaVertex, PreloadedVertex, PropertyKeyVertex, RelationTypeVertex, StandardEdge, StandardVertex, StandardVertexProperty, VertexLabelVertex

public interface JanusGraphElement
extends org.apache.tinkerpop.gremlin.structure.Element, Idfiable, Removable

JanusGraphElement represents the abstract concept of an entity in the graph and specifies basic methods for interacting with entities. The two basic entities in a graph database are JanusGraphRelation and JanusGraphVertex. Entities have a life cycle state which reflects the current state of the entity with respect to the JanusGraphTransaction in which it occurs. An entity may be in any one of these states and any given time:

• New: The entity has been created in the current transaction
• Loaded: The entity has been loaded from disk into the current transaction and has not been modified
• Modified: The entity has been loaded from disk into the current transaction and has been modified
• Deleted: The entity has been deleted in the current transaction

Depending on the concrete type of the entity, an entity may be identifiable, i.e. it has a unique ID which can be retrieved via id() (use hasId() to determine if a given entity has a unique ID).

Author:

Matthias Bröcheler (http://www.matthiasb.com)

See Also:

JanusGraphVertex, JanusGraphRelation

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.tinkerpop.gremlin.structure.Element

org.apache.tinkerpop.gremlin.structure.Element.Exceptions

Method Summary

Modifier and Type	Method and Description
JanusGraphTransaction	graph()
boolean	hasId() Checks whether this entity has a unique identifier.
default Object	id() Returns a unique identifier for this entity.
boolean	isLoaded() Checks whether this entity has been loaded into the current transaction and not yet modified.
boolean	isNew() Checks whether this entity has been newly created in the current transaction.
boolean	isRemoved() Checks whether this entity has been deleted into the current transaction.
long	longId() Unique identifier for this entity.
<V> org.apache.tinkerpop.gremlin.structure.Property<V>	property(String key, V value) Sets the value for the given key on this element.
void	remove() Deletes this entity and any incident edges or properties from the graph.
<V> V	valueOrNull(PropertyKey key) Retrieves the value associated with the given key on this element and casts it to the specified type.

Methods inherited from interface org.apache.tinkerpop.gremlin.structure.Element

keys, label, properties, property, value, values

Method Detail

graph

JanusGraphTransaction graph()

Specified by:

graph in interface org.apache.tinkerpop.gremlin.structure.Element

id

default Object id()

Returns a unique identifier for this entity.

The unique identifier may only be set when the transaction in which entity is created commits. Some entities are never assigned a unique identifier if they depend on a parent entity.

JanusGraph allocates blocks of identifiers and automatically assigns identifiers to elements automatically be default. This behavior can be partially overridden by setting GraphDatabaseConfiguration.ALLOW_SETTING_VERTEX_ID

Specified by:

id in interface org.apache.tinkerpop.gremlin.structure.Element

Returns:

The unique identifier for this entity

Throws:

IllegalStateException - if the entity does not (yet) have a unique identifier

See Also:

hasId()

longId

long longId()

Unique identifier for this entity. This id can be temporarily assigned and might change. Use id() for the permanent id.

Specified by:

longId in interface Idfiable

Returns:

Unique long id

hasId

boolean hasId()

Checks whether this entity has a unique identifier.

Note that some entities may never be assigned an identifier and others will only be assigned an identifier at the end of a transaction.

Returns:

true if this entity has been assigned a unique id, else false

See Also:

longId()

remove

void remove()

Deletes this entity and any incident edges or properties from the graph.

Specified by:

remove in interface org.apache.tinkerpop.gremlin.structure.Element

Specified by:

remove in interface Removable

Throws:

IllegalStateException - if the entity cannot be deleted or if the user does not have permission to remove the entity

property

<V> org.apache.tinkerpop.gremlin.structure.Property<V> property(String key,
                                                                V value)

Sets the value for the given key on this element. The key must be defined to have Cardinality.SINGLE, otherwise this method throws an exception.

Specified by:

property in interface org.apache.tinkerpop.gremlin.structure.Element

Parameters:

key - the string identifying the key

value - the object value

valueOrNull

<V> V valueOrNull(PropertyKey key)

Retrieves the value associated with the given key on this element and casts it to the specified type. If the key has cardinality SINGLE, then there can be at most one value and this value is returned (or null). Otherwise a list of all associated values is returned, or an empty list if non exist.

Parameters:

key - key

Returns:

value or list of values associated with key

isNew

boolean isNew()

Checks whether this entity has been newly created in the current transaction.

Returns:

True, if entity has been newly created, else false.

isLoaded

boolean isLoaded()

Checks whether this entity has been loaded into the current transaction and not yet modified.

Returns:

True, has been loaded and not modified, else false.

isRemoved

boolean isRemoved()

Checks whether this entity has been deleted into the current transaction.

Returns:

True, has been deleted, else false.