OrientDB在Java代码中的边缘上创建约束

Question

I have a few nodes in orientDB and i want to have constraints on the edges between them. For example i have a node type Master and a type Slave and i want to have edges only between master and slave and not between slaves.

I want to do this using a constraint on the relationshiop between master and slave. Is this possible using constraints?

Edit: I tried to do it like this, but it doesnt work, i can still add a slave pointing to a master. How do i access the schema when using a graph DB?

OrientGraph graph = new OrientGraph("remote:localhost/test");
    if (graph.getEdgeType("Ref") == null) {
        graph.createEdgeType("Ref");
    }
    if (graph.getVertexType("Element") == null) {
        graph.createVertexType("Element");
    }
    if (graph.getVertexType("SubElement") == null) {
        OrientVertexType subElementVertex = graph
                .createVertexType("SubElement");
        OrientVertexType elementVertex = graph.getVertexType("Element");
        subElementVertex
                .createProperty("parent", OType.LINK, elementVertex)
                .isMandatory();
    }

I'm using this to create my vertices and edges:

Vertex page3 = graph.addVertex("class:Element");
Vertex doc1 = graph.addVertex("class:SubElement");
page3.setProperty("type", "page");
doc1.setProperty("type", "document");

Edge edge6 = graph.addEdge("class:Ref", page3, doc1, "Ref");
edge6.setProperty("properties", mapEdge);
edge6.setProperty("type", "document");

Edge edge7 = graph.addEdge("class:Ref", doc1, page3, "Ref");

And that last one should not work, if the constraint is correct.

Answer 1

You can do this with the schema :

Master master = database.getMetadata().getSchema().createClass("Master");

Slave slave = database.getMetadata().getSchema().createClass("Slave");
slave.createProperty("parent", OType.LINK, master);

With graphs:

OrientEdgeType edge = graph.createEdgeType("MyEdge");
Edge e = subElementVertex.addEdge("Ref", elementVertex );