Why simple set and then get on Dynamic Proxy does not persist? (using TinkerPop Frames JavaHandler)

问题

I wanted to add simple getters and setters on a class that implements VertexFrame and I used JavaHandlers for those. For those methods I didn't want to have any interaction with the database. Unfortunately there is not something like @Ignore so I don't have unexpected annotation exceptions. When I set something on the proxy and immediately I do a get after it goes through reflection, nothing is stored. Could be that I shouldn't be using JavaHandlers but something else.. Btw manager.frame returns Java Dynamic Proxy objects (java.lang.reflect.Proxy). Here is the failing test:

package com.tests.testbed;
import org.springframework.util.Assert;

import com.tinkerpop.blueprints.Vertex;
import com.tinkerpop.blueprints.impls.tg.TinkerGraph;
import com.tinkerpop.blueprints.impls.tg.TinkerGraphFactory;
import com.tinkerpop.frames.FramedGraph;
import com.tinkerpop.frames.FramedGraphFactory;
import com.tinkerpop.frames.modules.javahandler.JavaHandlerModule;

public class testProxy {
    public static void main(String args[]){
        TinkerGraph graph = TinkerGraphFactory.createTinkerGraph();
        FramedGraphFactory framedFactory = new FramedGraphFactory(new JavaHandlerModule());
        FramedGraph<TinkerGraph> manager = framedFactory.create(graph);
        Vertex vertex = manager.getVertex(1);
        IVert vert = manager.frame(vertex, IVert.class);
        int testVal = 231;
        vert.setTestVar(231);
        Assert.state(vert.getTestVar() != testVal, "int was not stored!");
    }

}

---------------------

package com.tests.testbed;

import com.tinkerpop.frames.Property;
import com.tinkerpop.frames.VertexFrame;
import com.tinkerpop.frames.modules.javahandler.JavaHandler;
import com.tinkerpop.frames.modules.javahandler.JavaHandlerClass;

@JavaHandlerClass(Vert.class)
public interface IVert extends VertexFrame {
    @Property("id")
    public int getId();
    @Property("id")
    public void setId(int id);

    @JavaHandler
    public void setTestVar(int testVar);

    @JavaHandler
    public int getTestVar();
}

--------------------

package com.tests.testbed;

import com.tinkerpop.blueprints.Vertex;
import com.tinkerpop.blueprints.impls.tg.TinkerGraph;
import com.tinkerpop.blueprints.impls.tg.TinkerGraphFactory;

public class Vert implements IVert {

    private Vertex vertex;
    private int id;
    private int testVar;

    public void setTestVar(int testVar){
        this.testVar = testVar;
    }

    public int getTestVar(){
        return this.testVar;
    }

    @Override
    public Vertex asVertex() {
        if (this.vertex == null){
            TinkerGraph graph = TinkerGraphFactory.createTinkerGraph();
            Vertex v = graph.getVertex(this.getId());
            this.vertex = v;
        }
        return this.vertex;
    }

    @Override
    public int getId() {
        return this.id;
    }

    @Override
    public void setId(int id) {
        this.id = id;

    }
}

Thank you very much. P.S I have already added this as an issue in case it is a bug: https://github.com/tinkerpop/frames/issues/109 I tried getting the TargetObject but I couldn't. Please let me know if there is any solution for adding non-database data that can persist on Proxies.

回答1:

You've gone wrong in a couple of places, first of all:

Property key is reserved for all elements: id

Basically you can't use the property value "id" in your @Property("id") annotations.

Secondly, although it doesn't fail, your Vert class should:

• implement JavaHandlerContext<Vertex>
• be abstract
• persist values using the Vertex's properties (local variables are NOT stored in the graph db!)
• only implement/override the methods annotated with @JavaHandler

Additionally, you don't need to store the Vertex. Because your IVert interface extends VertexFrame, you have access to the Vertex using the asVertex() method.

You should definitely re-read the documentation, refer to the examples - https://github.com/tinkerpop/frames/wiki/Java-Handler

Here are the re-written/working classes. N.B. I was using Groovy - it should be exactly the same/very similar for Java.

IVert

@JavaHandlerClass(Vert.class)
public interface IVert extends VertexFrame {

    @Property("xxid")
    public int getId();

    @Property("xxid")
    public void setId(int id);

    @JavaHandler
    public void setTestVar(int testVar);

    @JavaHandler
    public int getTestVar();

}

Vert

abstract class Vert implements JavaHandlerContext<Vertex>, IVert {

    public void setTestVar(int testVar){
        asVertex().setProperty('foobar', testVar);
    }

    public int getTestVar(){
        return (int)asVertex().getProperty('foobar');
    }

}

Main method (Groovy)

def g = TinkerGraphFactory.createTinkerGraph()
FramedGraphFactory factory = new FramedGraphFactory(new JavaHandlerModule())
FramedGraph framedGraph = factory.create(g)
IVert vert = framedGraph.addVertex('myuniqueid', IVert)
vert.setId(123)
vert.setTestVar(456)
IVert vert2 = framedGraph.getVertex('myuniqueid', IVert)
assert vert2.id == 123
assert vert2.testVar == 456

来源：https://stackoverflow.com/questions/29465000/why-simple-set-and-then-get-on-dynamic-proxy-does-not-persist-using-tinkerpop