CODEWITHSUNDEEP
javajsonrestneo4jcypher
avh
avh

Reputation: 188

Parsing a cypher query result (JSON) to a Java object

I use the jersey/jackson stack to address a neo4j database via the REST api, but I have some issues how to interpret the result.

If I read the node by its ID (/db/data/node/xxx) the result can be mapped to my DTO very easy by calling readEntity(MyDto.class) on the response. However, usage of internal IDs is not recommended and various use cases require to query by custom properties. Here cypher comes into play (/db/data/cypher).

Assuming a node exists with a property "myid" and a value of "1234", I can fetch it with the cypher query "MATCH (n {myid: 1234}) RETURN n". The result is a JSON string with a bunch of resources and eventually the "data" I want do unmarshall to a java object. Unmarshalling it directly fails with a ProcessingException (error reading entity from input stream). I see no API allowing to iterate the result's data.

My idea is to define some kind of generic wrapper class with an attribute "data", giving this one to the unmarshaller, and unwrapping my DTO afterwards. I wonder if there is a more elegant way to do this, like using "RETURN n.data" (which does not work) or something like this. Is it?

Upvotes: 1

Views: 1879

Answers (1)

Michael Hunger
Michael Hunger

Reputation: 41676

You should look into neo4j 2.0 where return n just returns the property map.

I usually tend to deserialize the result as a nested list/map (i.e. have ObjectMapper read to Object.class or Map.class) structure and grab the data map directly out of that.

There's probably a way to tell jackson to ignore all the information around that data field

If you want to have a nicer presentation you can also check out my cypher-rs project which returns only the data in question, nothing more.

Upvotes: 3

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