How to get schema of a vertex label gremlin using graph.OpenManagement()

Question

i' have created label schema using graph.OpenManagement() as described in https://docs.janusgraph.org/basics/schema/#schema-constraints

mgmt = graph.openManagement()
person = mgmt.makeVertexLabel('person').make()
name = mgmt.makePropertyKey('name').dataType(String.class).cardinality(Cardinality.SET).make()
birthDate = mgmt.makePropertyKey('birthDate').dataType(Long.class).cardinality(Cardinality.SINGLE).make()
mgmt.addProperties(person, name, birthDate)
mgmt.commit()

How can I get the person label schema. What is the gremlin query to get the properties list along with the datatype and cardinality info for a label.

Im using the following query to get the properties list with the data type, but there is no map for property to the label

gremlin> mgmt.printPropertyKeys()
==>------------------------------------------------------------------------------------------------
Property Key Name              | Cardinality | Data Type                                          |
---------------------------------------------------------------------------------------------------
name2                          | SINGLE      | class java.lang.String                             |
age2                           | SINGLE      | class java.lang.Integer                            |
name3                          | SET         | class java.lang.String                             |
birthDate3                     | SINGLE      | class java.lang.Long                               |
name4                          | SET         | class java.lang.String                             |
birthDate4                     | SINGLE      | class java.lang.Long                               |
name6                          | SINGLE      | class java.lang.String                             |
age6                           | SINGLE      | class java.lang.Integer                            |
name5                          | SINGLE      | class java.lang.String                             |
age5                           | SINGLE      | class java.lang.Integer                            |
mean_radius                    | SINGLE      | class java.lang.Integer                            |
distance_in_kms                | SINGLE      | class java.lang.Integer                            |
new_field                      | SINGLE      | class java.lang.String                             |
radius_in_kms                  | SINGLE      | class java.lang.Integer                            |
name                           | SINGLE      | class java.lang.String                             |
---------------------------------------------------------------------------------------------------

Answer 1

Getting vertex labels and their basic information:

mgmt.getVertexLabels().forEach(vertexLabel -> {
    System.out.println("Vertex label: "+vertexLabel.name()+" isPartitioned: "+vertexLabel.isPartitioned()+" isStatic: "+vertexLabel.isStatic());
});

Getting edge labels and their basic information:

mgmt.getRelationTypes(EdgeLabel.class).forEach(edgeLabel ->{
    System.out.println("Edge label: "+edgeLabel.name()+" Multiplicity: "+edgeLabel.multiplicity().name()+" isUnidirected:"+edgeLabel.isUnidirected());
});

Getting properties and their basic information:

mgmt.getRelationTypes(PropertyKey.class).forEach(propertyKey -> {
    System.out.println("Property key: "+propertyKey.name()+" Cardinality: "+propertyKey.cardinality().name()+" Datatype: "+propertyKey.dataType().getName());
});

Now, when you got a specific Vertex label or a specific Edge label (as shown above), you can ask for the schema constraints information as shown below. Same methods are available for both VertexLabel and EdgeLabel.

Getting vertex label properties:

VertexLabel vertexLabel = mgmt.getVertexLabel("myVertexLabel");
vertexLabel.mappedProperties().forEach(propertyKey -> {
  // get information about `propertyKey` as shown above in `Getting properties and their basic information` section
});

Getting vertex label connections:

VertexLabel vertexLabel = mgmt.getVertexLabel("myVertexLabel");
vertexLabel.mappedConnections().forEach(connection -> {
  // connection.getEdgeLabel() - return the label of the edge. You can use it to access the edge itself if needed like: 
 EdgeLabel edgeLabel = mgmt.getEdgeLabel(connection.getEdgeLabel());
 // You can access JanusGraphEdge via:
 JanusGraphEdge janusGraphEdge = connection.getConnectionEdge();
 // Having JanusGraphEdge you can access EdgeLabel directly via:
 edgeLabel = janusGraphEdge.edgeLabel();
 // You can also access incoming or outgoing vertices of this connection via: connection.getIncomingVertexLabel() or connection.getOutgoingVertexLabel()
});