14.7.1 Managing Transient Properties

The graph server (PGX) adopts the Property Graph data model. Once a graph is loaded into PGX, the graph instance itself and its original properties are set as immutable. However, the client can create and attach additional properties to the graph dynamically. These extra properties are referred to as transient properties and are mutable by the client

The methods for creating transient properties are available in PgxGraph:

• Java
• Python

VertexProperty<ID, V> createVertexPropertyAsync(PropertyType type)
VertexProperty<ID, V> createVertexPropertyAsync(PropertyType type, String name)
EdgeProperty<V> createEdgePropertyAsync(PropertyType type)
EdgeProperty<V> createEdgePropertyAsync(PropertyType type, String name)

In the preceding code:

• PropertyType: is an enum for the data type of the property, which must be one of the primitive types supported by PGX.
• name: is an optional argument to assign a unique name to the newly created property. If no name is specified, PGX will assign one to the client.

  Note:

  Names must be unique. There cannot be two different vertex or edge properties for the same graph and with the same name.

create_vertex_property(self,data_type,name=None)

All methods return a Property object, which represent the newly created transient property. Both of the underlying classes, VertexProperty<ID, V> and EdgeProperty<V>, are parametrized with the value type V the property holds. V matches the given PropertyType. VertexProperty<ID, V> is additionally parametrized with the vertex ID type. This is due to PGX support of several types of vertex identifiers. See our graph configuration chapter on how to specify the vertex ID type of a graph. EdgeProperty<V> is not parametrized with the edge ID type, because PGX only supports edge identifiers of type long.

• Java
• Python

GraphConfig config = GraphConfigBuilder.forFileFormats(...)
    ...
    .setVertexIdType(IdType.LONG)
    ...
    .build();

PgxGraph G = session.readGraphWithProperties(config);
VertexProperty<Long, String> p1 = G.createVertexProperty(PropertyType.STRING);
EdgeProperty<Double> p2 = G.createEdgeProperty(PropertyType.DOUBLE);

G = session.read_graph_with_properties(config)
p1 = G.create_vertex_property("string")
p2 = G.create_edge_property("double")

To delete a transient property from the session, call destroyAsync() (or destroy()) on the property object.