org.neo4j.graphdb

Interface GraphDatabaseService

public interface GraphDatabaseService

The main access point to a running Neo4j instance. The most common implementation is the EmbeddedGraphDatabase class, which is used to embed Neo4j in an application. Typically, you would create an EmbeddedGraphDatabase instance as follows:

 GraphDatabaseService graphDb = new GraphDatabaseFactory().newEmbeddedDatabase( "var/graphDb" );
 // ... use Neo4j
 graphDb.shutdown();
 

GraphDatabaseService provides operations to create nodes, get nodes given an id and ultimately shutdown Neo4j.

Please note that all operations on the graph must be invoked in a transactional context. Failure to do so will result in a NotInTransactionException being thrown.

Method Summary

Methods

Modifier and Type	Method and Description
Transaction	beginTx() Starts a new transaction and associates it with the current thread.
BidirectionalTraversalDescription	bidirectionalTraversalDescription() Factory method for bidirectional traversal descriptions
Node	createNode() Creates a new node.
Node	createNode(Label... labels) Creates a new node and adds the provided labels to it.
ResourceIterable<Node>	findNodesByLabelAndProperty(Label label, String key, Object value) Returns all nodes having the label, and the wanted property value.
Iterable<Node>	getAllNodes() Deprecated. this operation can be found in GlobalGraphOperations instead.
Node	getNodeById(long id) Looks up a node by id.
Relationship	getRelationshipById(long id) Looks up a relationship by id.
Iterable<RelationshipType>	getRelationshipTypes() Deprecated. this operation can be found in GlobalGraphOperations instead.
IndexManager	index() Returns the IndexManager paired with this graph database service and is the entry point for managing indexes coupled with this database.
boolean	isAvailable(long timeout) Use this method to check if the database is in a usable state.
KernelEventHandler	registerKernelEventHandler(KernelEventHandler handler) Registers handler as a handler for kernel events which are generated from different places in the lifecycle of the kernel.
<T> TransactionEventHandler<T>	registerTransactionEventHandler(TransactionEventHandler<T> handler) Registers handler as a handler for transaction events which are generated from different places in the lifecycle of each transaction.
Schema	schema() Returns the schema manager where all things related to schema, for example constraints and indexing on labels.
void	shutdown() Shuts down Neo4j.
TraversalDescription	traversalDescription() Factory method for unidirectional traversal descriptions
KernelEventHandler	unregisterKernelEventHandler(KernelEventHandler handler) Unregisters handler from the list of kernel event handlers.
<T> TransactionEventHandler<T>	unregisterTransactionEventHandler(TransactionEventHandler<T> handler) Unregisters handler from the list of transaction event handlers.

Method Detail

createNode

Node createNode()

Creates a new node.

Returns:

the created node.

createNode

Node createNode(Label... labels)

Creates a new node and adds the provided labels to it.

Parameters:

labels - labels to add to the created node.

Returns:

the created node.

getNodeById

Node getNodeById(long id)

Looks up a node by id. Please note: Neo4j reuses its internal ids when nodes and relationships are deleted, which means it's bad practice to refer to them this way. Instead, use application generated ids.

Parameters:

id - the id of the node

Returns:

the node with id id if found

Throws:

NotFoundException - if not found

getRelationshipById

Relationship getRelationshipById(long id)

Looks up a relationship by id. Please note: Neo4j reuses its internal ids when nodes and relationships are deleted, which means it's bad practice to refer to them this way. Instead, use application generated ids.

Parameters:

id - the id of the relationship

Returns:

the relationship with id id if found

Throws:

NotFoundException - if not found

getAllNodes

@Deprecated
Iterable<Node> getAllNodes()

Deprecated. this operation can be found in GlobalGraphOperations instead.

Returns all nodes in the graph.

Returns:

all nodes in the graph.

findNodesByLabelAndProperty

ResourceIterable<Node> findNodesByLabelAndProperty(Label label,
                                                 String key,
                                                 Object value)

Returns all nodes having the label, and the wanted property value. If an online index is found, it will be used to look up the requested nodes.

If no indexes exist for the label/property combination, the database will scan all labeled nodes looking for the property value.

Note that equality for values do not follow the rules of Java. This means that the number 42 is equals to all other 42 numbers, indifferently of if they are encoded as Integer, Long, Float, Short, Byte or Double.

Same rules follow Character and String - the Character 'A' is equal to the String 'A'.

Finally - arrays also follow these rules. An int[] {1,2,3} is equal to a double[] {1.0, 2.0, 3.0}

Please ensure that the returned ResourceIterable is closed correctly and as soon as possible inside your transaction to avoid potential blocking of write operations.

Parameters:

label - consider nodes with this label

key - required property key

value - required property value

Returns:

an iterable containing all matching nodes. See { @link ResourceIterable } for responsibilities.

getRelationshipTypes

@Deprecated
Iterable<RelationshipType> getRelationshipTypes()

Deprecated. this operation can be found in GlobalGraphOperations instead.

Returns all relationship types currently in the underlying store. Relationship types are added to the underlying store the first time they are used in a successfully commited node.createRelationshipTo(...). Note that this method is guaranteed to return all known relationship types, but it does not guarantee that it won't return more than that (e.g. it can return "historic" relationship types that no longer have any relationships in the node space).

Returns:

all relationship types in the underlying store

isAvailable

boolean isAvailable(long timeout)

Use this method to check if the database is in a usable state. If the database is currently not in a usable state, you can provide a timeout to wait for it to become so. If the database has been shutdown this immediately returns false.

shutdown

void shutdown()

Shuts down Neo4j. After this method has been invoked, it's invalid to invoke any methods in the Neo4j API and all references to this instance of GraphDatabaseService should be discarded.

beginTx

Transaction beginTx()

Starts a new transaction and associates it with the current thread.

All database operations must be wrapped in a transaction.

If you attempt to access the graph outside of a transaction, those operations will throw NotInTransactionException.

Please ensure that any returned ResourceIterable is closed correctly and as soon as possible inside your transaction to avoid potential blocking of write operations.

Returns:

a new transaction instance

registerTransactionEventHandler

<T> TransactionEventHandler<T> registerTransactionEventHandler(TransactionEventHandler<T> handler)

Registers handler as a handler for transaction events which are generated from different places in the lifecycle of each transaction. To guarantee that the handler gets all events properly it shouldn't be registered when the application is running (i.e. in the middle of one or more transactions). If the specified handler instance has already been registered this method will do nothing.

Type Parameters:

T - the type of state object used in the handler, see more documentation about it at TransactionEventHandler.

Parameters:

handler - the handler to receive events about different states in transaction lifecycles.

Returns:

the handler passed in as the argument.

unregisterTransactionEventHandler

<T> TransactionEventHandler<T> unregisterTransactionEventHandler(TransactionEventHandler<T> handler)

Unregisters handler from the list of transaction event handlers. If handler hasn't been registered with registerTransactionEventHandler(TransactionEventHandler) prior to calling this method an IllegalStateException will be thrown. After a successful call to this method the handler will no longer receive any transaction events.

Type Parameters:

T - the type of state object used in the handler, see more documentation about it at TransactionEventHandler.

Parameters:

handler - the handler to receive events about different states in transaction lifecycles.

Returns:

the handler passed in as the argument.

Throws:

IllegalStateException - if handler wasn't registered prior to calling this method.

registerKernelEventHandler

KernelEventHandler registerKernelEventHandler(KernelEventHandler handler)

Registers handler as a handler for kernel events which are generated from different places in the lifecycle of the kernel. To guarantee proper behavior the handler should be registered right after the graph database has been started. If the specified handler instance has already been registered this method will do nothing.

Parameters:

handler - the handler to receive events about different states in the kernel lifecycle.

Returns:

the handler passed in as the argument.

unregisterKernelEventHandler

KernelEventHandler unregisterKernelEventHandler(KernelEventHandler handler)

Unregisters handler from the list of kernel event handlers. If handler hasn't been registered with registerKernelEventHandler(KernelEventHandler) prior to calling this method an IllegalStateException will be thrown. After a successful call to this method the handler will no longer receive any kernel events.

Parameters:

handler - the handler to receive events about different states in the kernel lifecycle.

Returns:

the handler passed in as the argument.

Throws:

IllegalStateException - if handler wasn't registered prior to calling this method.

schema

Schema schema()

Returns the schema manager where all things related to schema, for example constraints and indexing on labels.

Returns:

the schema manager for this database.

index

IndexManager index()

Returns the IndexManager paired with this graph database service and is the entry point for managing indexes coupled with this database.

Returns:

the IndexManager for this database.

traversalDescription

TraversalDescription traversalDescription()

Factory method for unidirectional traversal descriptions

bidirectionalTraversalDescription

BidirectionalTraversalDescription bidirectionalTraversalDescription()

Factory method for bidirectional traversal descriptions