https://github.com/sim51/noqm
Neo4j Object Query Mapper
https://github.com/sim51/noqm
cypher java neo4j orm query
Last synced: 2 months ago
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Neo4j Object Query Mapper
- Host: GitHub
- URL: https://github.com/sim51/noqm
- Owner: sim51
- License: mit
- Created: 2017-06-13T15:36:50.000Z (almost 8 years ago)
- Default Branch: master
- Last Pushed: 2017-07-15T16:09:09.000Z (almost 8 years ago)
- Last Synced: 2025-01-24T16:44:31.819Z (4 months ago)
- Topics: cypher, java, neo4j, orm, query
- Language: Java
- Homepage: https://sim51.github.io/NOQM
- Size: 3.04 MB
- Stars: 1
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.adoc
- License: LICENSE
Awesome Lists containing this project
README
= Neo4j Object Query Mapper
Benoit Simard
:experimental:
:outfilesuffix-old: {outfilesuffix}
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https://sim51.github.io/NOQM
image:https://travis-ci.org/sim51/NOQM.svg?branch=master["Build Status", link="https://travis-ci.org/sim51/NOQM"]
image:https://coveralls.io/repos/github/sim51/NOQM/badge.svg?branch=master["Coverage Status, link="https://coveralls.io/github/sim51/NOQM?branch=master"]
== Why this project ?
It's not an OGM (object graph mapper), this project is just a stupid client on top of the neo4j java driver.
* Simple and small Neo4j client
* Singleton for the Neo4j Driver (as needed)
* Simple and single configuration file
* Easy to switch from single to cluster architecture
* Using java stream (for now the neo4j java driver doesn't used it, but it should appears in a future)
* Stupid query object mapping, via a projection system
== Limitation
* You can use only one Neo4j database.
* You can't make multi-transaction on the same session. This can be useful on cluster mode, but you can manage it with bookmarkId.
== Installation
Firstly you have to add the maven repository of the project to your *pom.xml* :
[source,xml]
----
NOQM-mvn-repo
https://raw.github.com/sim51/NOQM/mvn-repo/
true
always
----
Then you can add the dependency :
[source,xml]
----
org.neo4j.contrib
NOQM
1.0-SNAPSHOT
----
== Configuration
All the configuration comes from one file : **neo4j-driver.properties**
This should be at the root of the classpath.
[source,properties]
----
# Neo4j driver url
neo4j.url=bolt://localhost
neo4j.user=neo4j
neo4j.password=test
# (int) Max number of idle connection into the pool
#neo4j.maxIdleConnectionPoolSize=5
# (long) Threshold of idle time from which we test a connection (in seconds)
#neo4j.idleTimeBeforeConnectionTest=0
# (boolean) Do we log leaked session ?
#neo4j.logLeakedSessions=true
# (boolean) Traffic encrypted ?
#neo4j.encrypted=false
# Valid values are :
# - ALL : Trust strategy for certificates that can be verified through the local system store.
# - SYSTEM : Trust strategy for certificates that can be verified through the local system store.
# - A certificate file (ex: /etc/ssl/mycert.cet)
#neo4j.trustStrategy=ALL
# Specify socket connection timeout in millisecond
#neo4j.connectionTimeoutMillis=5000
----
NOTE: To make this configuration dynamic, you can use some maven filters
IMPORTANT: You can override those properties, with a second files named : **neo4j-driver-ext.properties** . This file must be also at the root of the classpath, like into the **shared/classes/** folder of a tomcat server.
== How to use it ?
=== Auto-commit mode
Just call it like this for a read query
[source,java]
----
import org.neo4j.driver.*
import static org.neo4j.driver.v1.Values.parameters;
...
try(Stream rs = Neo4jClient.read("MATCH (n:Person { name:$name, born:$born }) RETURN n", parameters( "name", "Keanu Reeves", "born", 1964 ))) {
rs.forEach((record) -> {
System.out.println(record);
});
}
----
And for a write query :
[source,java]
----
Neo4jClient
.write("CREATE (n:Person { name:$name, born:$born }) RETURN n", parameters( "name", "Keanu Reeves", "born", 1964 ))
.close();
----
IMPORTANT: It's important to notice, that you have to close the stream (underlying, it's closing the session), with a `try-with-resource` or by calling the the stream's `close` method.
=== Transaction mode
Firstly you have to create a read or write `Transaction` within a `try-with-resource` block.
Then you can make some queries.
[source,java]
----
String bookmarkId = null;
try ( Neo4jTransaction tx = Neo4jClient.getWriteTransaction()) {
tx.run("CREATE (me:Person { name:$name, born:$born }) RETURN me", parameters( "name", "Benoit", "born", 1983 )).close();
}
----
=== Projection system
If you don't want to have a stream of `Record`, you can use the *Projection System*.
It's just a list of some *Map* functions to transform a record to some class.
To use it, you have to *map* the stream with : `Projections.as(MyClass.class)`
[source,java]
----
List movies = Neo4jClient
.read("MATCH (n:Movie) RETURN n.title AS title, n.tagline AS tagline, n.released AS released")
.map(Projections.as(Movie.class))
.collect(Collectors.toList())
----
Where `Movie` is a simple object :
[source,java]
----
package org.neo4j.driver.projection.pojo;
import lombok.Data;
@Data
public class Movie {
public String title;
public String tagline;
public Integer released;
}
----
On this example, I use the https://projectlombok.org[lombok project] to generate all setters of this class.
The projection system is entirely based on *setter*. It search a method that :
* match the name of a column (for `movie`, it search for `setMovie`)
* without any return ( a void method)
* with only one argument
When found, it tries to cast from the driver type to the argument type.
Take a look at this test for more example : `src/text/java/org/neo4j/driver/projection/ProjectionTest`.
== Test requirement
This project has a dependency on https://github.com/neo4j-contrib/boltkit[Boltkit] for the test.
So you have to install it before to launch tests.