Perfect. Thanks David. I have an exactly similar model with a slightly more
complicated structure :).
I will keep you updated with my project (totally based on neo4j and SDG)
as I plan to open source it eventually.
I have one more question for you :
I see the latest release changes NodeGraphRepository from interfaces to
classes( RC1 to RELEASE)
What necessitated this change and are there any release notes with detailed
explanations about changes which I can refer to ?
I am finding it hard to map out the changes
On Thu, Apr 21, 2011 at 12:09 AM, David Montag <
david.mon...@neotechnology.com> wrote:
> Hi Vipul,
>
> Thanks for listening!
>
> It's a very good question, and the short answer is: yes! I'm cc'ing our
> mailing list so that everyone can take part in the answer.
>
> Here's the long answer, illustrated by an example:
>
> Let's assume you're modeling a network. You'll have some domain classes
> that are all networked entities with peers:
>
> @NodeEntity
> public class NetworkEntity {
> @RelatedTo(type = "PEER", direction = Direction.BOTH, elementClass =
> NetworkEntity.class)
> private Set<NetworkEntity> peers;
>
> public void addPeer(NetworkEntity peer) {
> peers.add(peer);
> }
> }
>
> public class Server extends NetworkEntity {}
> public class Router extends NetworkEntity {}
> public class Client extends NetworkEntity {}
>
> Then we can build a small network:
>
> Client c = new Client().persist();
> Router r1 = new Router().persist();
> Router r21 = new Router().persist();
> Router r22 = new Router().persist();
> Router r3 = new Router().persist();
> Server s = new Server().persist();
>
> c.addPeer(r1);
> r1.addPeer(r21);
> r1.addPeer(r22);
> r21.addPeer(r3);
> r22.addPeer(r3);
> r3.addPeer(s);
>
> c.persist();
>
> Note that after linking the entities, I only call persist() on the client.
> You can read more about this in the reference documentation, but essentially
> it will cascade in the direction of the relationships created, and will in
> this case cascade all the way to the server entity.
>
> You can now query this:
>
> Iterable<EntityPath<Client, Server>> paths =
> c.findAllPathsByTraversal(Traversal.description());
>
> The above code will get you an EntityPath per node visited during the
> traversal from c. The example does however not use a very interesting
> traversal description, but you can still print the results:
>
> for (EntityPath<Client, Server> path : paths) {
> StringBuilder sb = new StringBuilder();
> Iterator<NetworkEntity> iter =
> path.<NetworkEntity>nodeEntities().iterator();
> while (iter.hasNext()) {
> sb.append(iter.next());
> if (iter.hasNext()) sb.append(" -> ");
> }
> System.out.println(sb);
> }
>
> This will print each path, with all entities in the path. This is what it
> looks like:
>
> domain.Client@1
> domain.Client@1 -> domain.Router@2
> domain.Client@1 -> domain.Router@2 -> domain.Router@3
> domain.Client@1 -> domain.Router@2 -> domain.Router@3 ->
> domain.Router@5
> domain.Client@1 -> domain.Router@2 -> domain.Router@3 ->
> domain.Router@5 -> domain.Server@6
> domain.Client@1 -> domain.Router@2 -> domain.Router@3 ->
> domain.Router@5 -> domain.Router@4
>
> Let us know if this is what you looked for. If you want to only find paths
> that end with a server, you'd use this query instead:
>
> Iterable<EntityPath<Client, Server>> paths =
> c.findAllPathsByTraversal(Traversal.description().evaluator(new Evaluator()
> {
> @Override
> public Evaluation evaluate(Path path) {
> if (new ConvertingEntityPath(graphDatabaseContext,
> path).endEntity() instanceof Server) {
> return Evaluation.INCLUDE_AND_PRUNE;
> }
> return Evaluation.EXCLUDE_AND_CONTINUE;
> }
> }));
>
> In the above code example, graphDatabaseContext is a bean of type
> GraphDatabaseContext created by Spring Data Graph. This syntax will
> dramatically improve in future releases. It will print:
>
> domain.Client@1 -> domain.Router@2 -> domain.Router@3 ->
> domain.Router@5 -> domain.Server@6
>
> Regarding your second question about types: If you want to convert a node
> into an entity, you would use the TypeRepresentationStrategy configured
> internally in Spring Data Graph. See the reference documentation for more
> information on this. If you want to convert Neo4j paths to entity paths, you
> can use the ConvertingEntityPath class as seen above. As an implementation
> detail, the class name is stored on the node as a property.
>
> Hope this helped!
>
> David
>
> On Wed, Apr 20, 2011 at 9:20 AM, Emil Eifrem <e...@neotechnology.com>wrote:
>
>> David / Michael, do you guys want to dig in and help out Vipul below?
>>
>> -EE
>>
>> On Wed, Apr 20, 2011 at 09:17, Vipul Gupta <vipulgupta...@gmail.com>
>> wrote:
>> > Hi Emil,
>> > I would like to start by thanking you for the webinar. It was very
>> useful .
>> > This is the question I asked on the webinar as well.
>> > How can we traverse a graph which consists of nodes of different types
>> using
>> > SDG?
>> > Say first Node in relationship is of type A, next 3 nodes in path are of
>> > type B, and next node is of type C.
>> > Is there a way to traverse the path and keep getting the domain objects
>> at
>> > each stage of traversal.
>> > answer mentioned on the webinar is to look at findAllPathsByTraversal in
>> > NodeBacked.
>> > I am not able to understand how to get an Iterator or a path with starts
>> > with Type A, ends with Type C and has number of Type C in between.
>> >
>> > Also if I convert a domain POJO to a Node object, is there a way to know
>> > what domain type it represents or is wrapped around so that it can be
>> > converted back to that type.
>> > Please let me know.
>> > Best Regards,
>> > Vipul Gupta
>>
>>
>>
>> --
>> Emil Eifrém, CEO [e...@neotechnology.com]
>> Neo Technology, www.neotechnology.com
>> Cell: +46 733 462 271 | US: 206 403 8808
>> http://blogs.neotechnology.com/emil
>> http://twitter.com/emileifrem
>>
>
>
>
> --
> David Montag <david.mon...@neotechnology.com>
> Neo Technology, www.neotechnology.com
> Cell: 650.556.4411
> Skype: ddmontag
>
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