java neo4j creating node with cypher: java.lang.String cannot be cast to java.util.Map

Question

Hi Graphista and other Java gurus,

I have changed my code according to answer given and after inspecting the example provided by neo4j, but still to no avail. So please, could anyone help me with this???

I have a java program which connects to a Neo4J REST API endpoint via jersey client (version 2.11 from org.glassfish.jersey.core).

this is what I do:

        logger.trace("sending cypher {} to endpoint {}", cypherString, nodePointUrl);
        WebResource resource2 = Client.create().resource( nodePointUrl );

        ClientResponse response2 = resource2
                .accept( "application/json" )
                .type( "application/json" )
                .entity( cypherString )
                .post( ClientResponse.class );

        logger.debug("POST to {} returned status code {}, returned data: {}",
                nodePointUrl, response2.getStatus(),
                response2.getEntity(String.class));

        HttpStatusCodes httpStatusCodes = HttpStatusCodes.getHttpStatusCode(response2.getStatus());

The json in the cypherstring I send to the rest api looks like this:

{"CREATE": [{"POST": {"id":"532552232906940416","text":"Warburg Research...","subject":"Warburg Research ...","teaser":"Warburg Research...","lang":"de"}}]}

The error message I receive on this is:

 java.lang.String cannot be cast to java.util.Map

As you can see, my code is rather simple. I have taken it straight from neo4j website (http://neo4j.com/docs/stable/server-java-rest-client-example.html) - but it always bails out (see log below).

Please see the error log and give me a hint on what I did wrong.

Thanks in advance,

Christian

"message" : "java.lang.String cannot be cast to java.util.Map",
"exception" : "BadInputException",
"fullname" : "org.neo4j.server.rest.repr.BadInputException",
"stacktrace" : [ "org.neo4j.server.rest.repr.formats.JsonFormat.readMap(JsonFormat.java:92)", "org.neo4j.server.rest.web.RestfulGraphDatabase.createNode(RestfulGraphDatabase.java:238)", "java.lang.reflect.Method.invoke(Method.java:606)", "org.neo4j.server.rest.transactional.TransactionalRequestDispatcher.dispatch(TransactionalRequestDispatcher.java:139)", "java.lang.Thread.run(Thread.java:745)" ],
"cause" : {
   "message" : "java.lang.String cannot be cast to java.util.Map",
   "exception" : "ClassCastException",
   "stacktrace" : [ "org.neo4j.server.rest.domain.JsonHelper.jsonToMap(JsonHelper.java:53)", "org.neo4j.server.rest.repr.formats.JsonFormat.readMap(JsonFormat.java:88)", "org.neo4j.server.rest.web.RestfulGraphDatabase.createNode(RestfulGraphDatabase.java:238)", "java.lang.reflect.Method.invoke(Method.java:606)", "org.neo4j.server.rest.transactional.TransactionalRequestDispatcher.dispatch(TransactionalRequestDispatcher.java:139)", "java.lang.Thread.run(Thread.java:745)" ],
  "fullname" : "java.lang.ClassCastException"
  }
}

can you share your cypher statement and the URL that you are posting to? — Michael Hunger
– Michael Hunger, Commented Nov 13, 2014 at 0:47
yes, sure. my cypher statement is this: {"statements": [ {"statement": "CREATE" (p:"POST" {"id":"532769886335168512","text":"my text","lang":"de"}) }]} and I'm sending it to endpoint localhost:7474/db/data/transaction. the json-string for the attributes is created with the toJsonString() method, and I add the statements-part together with corresponding parentheses before sending it over the wire. — siliconchris
– siliconchris, Commented Nov 13, 2014 at 21:14
Any chance, anyone can help me here??? I'm still completely stuck. I now use the transaction endpoint and my cypher-statement is, as you can see, according to the examples given by neo4j, but still I receive this error: Neo.ClientError.Request.InvalidFormat","message":"Unable to deserialize request: Unexpected character ('(' (code 40)): was expecting comma to separate OBJECT entries — siliconchris
– siliconchris, Commented Nov 17, 2014 at 20:16

joslinm · Accepted Answer · 2014-11-11 22:22:35Z

3

If your cypherString looks like that, then it's probably wrong. It's trying to parse JSON, and you're not providing it JSON. As you can see from the example, their payload is:

String payload = "{\"statements\" : [ {\"statement\" : \"" +query + "\"} ]}";

You should do the same thing, but replace query with your variable, cypherString. As a result, you would have:

String payload = "{\"statements\" : [ {\"statement\" : \"" + cypherString + "\"} ]}";
ClientResponse response = resource
        .accept( MediaType.APPLICATION_JSON )
        .type( MediaType.APPLICATION_JSON )
        .entity( payload )
        .post( ClientResponse.class );

answered Nov 11, 2014 at 22:22

joslinm

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6 Comments

siliconchris Over a year ago

Ok, maybe I'm somewhat stupid here, but after changing my cypher statement, I receive a different error. This is my new cypher statement: {"CREATE" : [ {"s" : "POST" {"id":"532466871140753408","text":"hier ist der text","lang":"de"}} ]}. This is the new error: "java.lang.String cannot be cast to java.util.Map",

joslinm Over a year ago

I don't know what you're doing, but you need a structure that looks like this { "statements": [ {"statement": "CREATE (p:Post {id: 523, text: "hier ist der text", lang: "de"}) RETURN p ] } Neo4j will parse the JSON for the cypher query(s).

siliconchris Over a year ago

I have edited my statement as below: {"statements": [ {"statement": "CREATE" (p:"POST" {"id":"532555943180263424","text":"mein text","subject":"mein subject","teaser":"mein teaser","lang":"de"})}]} but still the same result

Eve Freeman Over a year ago

you're sending it to the wrong endpoint, I think. Make sure you're sending the post to the transactional cypher endpoint URL, not the node endpoint.

siliconchris Over a year ago

Actually the " around the keys are automatically generated by the toJsonString() method. But nevertheless, you are right. It's my first time with neo4j, so I expected a learning curve :-)

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