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I'm having trouble with the Graph API of OrientDB in Java.

Problem:

Retrieve Vertices (OrientVertex or Vertex?) from a persistent local graph database with several Vertices/Edges created via the console.

So for, I've been able to query the database from what I now think is the Document API using

graph = factory.getTx();
String string = String.format("select * from V where name like \"%s\"", criteria);
OSQLSynchQuery<ODocument> query = new OSQLSynchQuery<OrientVertex>(string);
List<OrientDocument> results = graph.getRawGraph().command(query).execute();

But this will not work for Vertices. How do I run queries that return a list of Vertices in my database?

Thanks in advance.

Ethan Hohensee
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  • Specifically, the documentation is very good on how to write the queries, but not so clear on how to actually **use** the queries. – Ethan Hohensee Dec 02 '14 at 19:16

3 Answers3

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You can avoid getting the rawGraph and executed command directly with orientGraph and returns an iterable of OrientVertex

like this :

graph = factory.getTx();
String query = String.format("select * from V where name like \"%s\"", criteria);
OSQLSynchQuery<OrientVertex> qr = new OSQLSynchQuery<OrientVertex>(query);
Iterable<OrientVertex> vertices = graph.command(qr).execute();
heroin
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wolf4ood
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  • Note that if using `orientGraph#command(...)`, the command is executed **outside** the transaction. – rmuller Dec 03 '14 at 09:46
  • This would be better, but execution outside of the transaction doesn't sound like a good thing. Is there an instance in which i **should** be using this method? Doesn't this break ACID principals? I can still write a SQL query and use wildcards with this method. – Ethan Hohensee Dec 03 '14 at 12:44
3

Looking at your code, you are using the Graph API. After calling getRawGraph() you are not working with the Graph API any more, but with the Document API (method name is a little bit confusing).

Having a reference to the OrientGraph there are several possibilities

  • Using orientGraph#getVertex*(..) / orientGraph#getVertices*(..)style of methods
  • Using a Query object: orientGraph#query().has("key", value).vertices()
  • Using the gremlin query language
  • Using orientGraph#command(...).execute(). In this case the command is executed outside the transaction (thanks @wolf4ood)
rmuller
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  • The `getVertex` and `getVertices` seem to return Blueprint `Vertex` data types, not `OrientVertex` which means I lose some of the advantages of `OrientVertex`. I'll try the query object and report back. Thank you for your help. – Ethan Hohensee Dec 02 '14 at 19:43
  • `graph.query().has("name").vertices()` seems to return `Iterable`. Is there no way to get OrientVertex objects out of the database? – Ethan Hohensee Dec 02 '14 at 19:47
  • It is simple to cast them to `OrientVertex`. They return `Vertex` because some methods implement the Blueprints API. Other methods (labelled with "Blueprints Extension") return OrientVertex. Take a look at the API doc. So the **implementation** is `OrientVertex` in all cases! – rmuller Dec 02 '14 at 19:48
  • @rmuller is there any way to use graph.query() by specified class, not by all V objects? – heroin Aug 02 '15 at 12:25
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    @heroin Not that I am aware of. Should use `getVertices(String label, String[] iKey, Object[] iValue)` – rmuller Aug 02 '15 at 14:50
  • Thanks, it is the thing I was looking for. – heroin Aug 02 '15 at 19:14
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Sometimes we want to retrieve Vertices specially based on other properties like names ,age etc so, I used getVertices() method to get the iterator and then extracted the vertex since getVertexByKey() is deprecated now.The code is: Vertex v2=graph.getVertices("name","Business").iterator().next();

So we just got the vertex without knowing the RID of the record. I don't know whether this is the best method to do this but it does the job.

Abhimanyu Shekhawat
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