RxJava - a powerful fluent API for processing results in a functional/reactive pattern
Jackson - the most fluent Java API for processing JSON
OkHttp - a fluent HTTP client
The Neo4J Cypher REST API combines the power of the Cypher query language with a JSON-native API that is very easy to process.
The examples below should make this very clear.
NeoRx is available from maven central:
<dependency>
<groupId>io.macgyver.neorx</groupId>
<artifactId>neorx</artifactId>
<version>1.1.1</version>
</dependency>or if you are lucky enough to be using Gradle:
compile "io.macgyver.neorx:neorx:1.1.1"Instantiate the (thread-safe) client:
// to http://localhost:7474
NeoRxClient client = new NeoRxClientBuilder().build();
// to https://neo4j.example.com:7473
client = new NeoRxClientBuilder.url("https://neo4j.example.com:7473").build();
// to https://neo4j.example.com:7473 with certificate validation disabled
client = new NeoRxClientBuilder().url("https://neo4j.example.com:7473").withCertificateValidation(false).build();
// with basic auth
client = new NeoRxClientBuilder().url("http://localhost:7474").credentials("myusername","mypassword").build();
Find all of the people in the graph who are born after 1980 and print the results using a Java 8 Lambda:
client.execCypher("match (p:Person) where p.born>1980 return p")
.subscribe(it -> System.out.println(it));
Output:
{"name":"Jonathan Lipnicki","born":1990}
{"name":"Natalie Portman","born":1981}
{"name":"Emile Hirsch","born":1985}
{"name":"Rain","born":1982}Same query, but print just the name:
client.execCypher("match (p:Person) where p.born>1960 return p")
.subscribe(
it -> System.out.println(it.path("name").asText()
);
Output:
Jonathan Lipnicki
Natalie Portman
Emile Hirsch
RainAnd now return the attributes individually:
client.execCypher("match (p:Person) where p.born>1980 return p.name, p.born")
.subscribe(
it -> System.out.println(it.path("p.name").asText()+" - "+it.path("p.born").asInt())
);
Output:
Jonathan Lipnicki - 1990
Natalie Portman - 1981
Emile Hirsch - 1985
Rain - 1982If you are stuck with Java 7:
neoRxClient.execCypher("match (p:Person) where p.born>1980 return p")
.subscribe(
new Action1<JsonNode>() {
@Override
public void call(JsonNode t1) {
System.out.println("Name: "+t1.path("name").asText();
}
});If you just want a list:
List<JsonNode> people = client.execCypher("match (p:Person) where p.born>1980 return p")
.toList()
.toBlocking()
.first();
And the same operation, through a convenience method:
List<JsonNode> people = client
.execCypherAsList("match (p:Person) where p.born>1980 return p");
This example shows the use of an Rx function to transform the result from JsonNode to String:
List<String> names = neoRxClient
.execCypher("match (p:Person) where p.born>1980 return p.name")
.flatMap(NeoRxFunctions.jsonNodeToString())
.toList()
.toBlocking().first();Now, let's parameterize the cypher quey:
List<JsonNode> people = client
.execCypherAsList("match (p:Person) where p.born>{year} return p","year",1980);
Sometimes you want to be able to set properties in bulk without specifying them in cypher.
This will upsert the node and update the values of foo and bar:
ObjectNode p = mapper.createObjectNode().put("foo","123").put("bar","456");
client.execCypher("MERGE (x:Dummy {name: "something" }) set x += {props} return x","props",p);