Following GRAPHSON format not working - titan

Question

I Am trying to convert the following graphSon Format into a graph instance
using the follwing command
graph.io(IoCore.graphson()).reader().create().readGraph(stream, graph);
But while running converting the GRaphSON into graph instance given
below
{"id":0,
"label":"buyer",
"outE":
{"email_is":
[{"id":0,"inV":1,
"properties":{"weight":1}
}
]}
,"properties":
{"buyer":
[{
"id":0,"value":"buyer0"
}]
,"age":
[{
"id":1,"value":10}]
}}
{"id":1,
"label":"email",
"inE":
{ "email_is":
[{"id":1,"outV":0,
"properties":{"weight":1}}
]}
,"properties":
{"email":
[{"id":2,
"value":"email0"
}]
}}
I am getting the following error
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.codehaus.mojo.exec.ExecJavaMojo$1.run(ExecJavaMojo.java:293)
at java.lang.Thread.run(Thread.java:745)Caused by: java.lang.IllegalArgumentException: Invalid vertex provided: null
at com.google.common.base.Preconditions.checkArgument(Preconditions.java:145)
at com.thinkaurelius.titan.graphdb.vertices.AbstractVertex.addEdge(AbstractVertex.java:149)
at com.thinkaurelius.titan.graphdb.vertices.AbstractVertex.addEdge(AbstractVertex.java:23)
at org.apache.tinkerpop.gremlin.structure.io.graphson.GraphSONReader.lambda$null$57(GraphSONReader.java:114)
at java.util.Iterator.forEachRemaining(Iterator.java:116)
at org.apache.tinkerpop.gremlin.structure.io.graphson.GraphSONReader.lambda$readGraph$58(GraphSONReader.java:108)
at java.util.HashMap$EntrySet.forEach(HashMap.java:1035)
at org.apache.tinkerpop.gremlin.structure.io.graphson.GraphSONReader.readGraph(GraphSONReader.java:108)
at pluradj.titan.tinkerpop3.example.JavaExample2.main(JavaExample2.java:50)
... 6 more
Can anyone tell me an easier way to make GRAPHSON file , as it is a very tedious task using StringWriter and JSONWRiter classes.

Answer 1

It doesn't look like there is anything wrong with your format except that you have line breaks where GraphSON's adjacency list requires one vertex per line as so:
{"id":0,"label":"buyer","outE":{"email_is":[{"id":0,"inV":1,"properties":{"weight":1}}]},"properties":{"buyer":[{"id":0,"value":"buyer0"}],"age":[{"id":1,"value":10}]}}
{"id":1,"label":"email","inE":{ "email_is":[{"id":1,"outV":0,"properties":{"weight":1}}]},"properties":{"email":[{"id":2,"value":"email0"}]}}
In this format it seems to work just fine:
gremlin> graph = TitanFactory.open('conf/titan-berkeleyje.properties')
==>standardtitangraph[berkeleyje:/db/berkeley]
gremlin> graph.io(graphson()).readGraph('data/sample.json')
==>null
gremlin> g = graph.traversal()
==>graphtraversalsource[standardtitangraph[berkeleyje:/db/berkeley], standard]
gremlin> g.V().valueMap()
==>[email:[email0]]
==>[age:[10], buyer:[buyer0]]
If you want to have "valid" JSON, then you can do this (which is only practical for small graphs):
{
"vertices": [
{"id":0,"label":"buyer","outE":{"email_is":[{"id":0,"inV":1,"properties":{"weight":1}}]},"properties":{"buyer":[{"id":0,"value":"buyer0"}],"age":[{"id":1,"value":10}]}},
{"id":1,"label":"email","inE":{ "email_is":[{"id":1,"outV":0,"properties":{"weight":1}}]},"properties":{"email":[{"id":2,"value":"email0"}]}}
]
}
and then you have to initialize the GraphSONReader a little differently and use the unwrapAdjacencyList setting:
gremlin> graph = TitanFactory.open('conf/titan-berkeleyje.properties')
==>standardtitangraph[berkeleyje:/db/berkeley]
gremlin> reader = graph.io(graphson()).reader().unwrapAdjacencyList(true).create()
==>org.apache.tinkerpop.gremlin.structure.io.graphson.GraphSONReader#286090c
gremlin> reader.readGraph(new FileInputStream('data/sample.json'), graph)
==>null
gremlin> g = graph.traversal()
==>graphtraversalsource[standardtitangraph[berkeleyje:/db/berkeley], standard]
gremlin> g.V().valueMap()
==>[age:[10], buyer:[buyer0]]
==>[email:[email0]]