# Spring Data Key Value

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The primary goal of the http://projects.spring.io/spring-data[Spring Data] project is to make it easier to build Spring-powered applications that use data access technologies. This module provides infrastructure components to build repository abstractions for stores dealing with Key/Value pairs and ships with a default `java.util.Map` based implementation.

## Features

* Infrastructure for building repositories on top of key/value implementations.
* Dynamic SpEL query generation from query method names.
* Possibility to integrate custom repository code.


## Quick Start

Download the jar through Maven:

[source, xml]
----
<dependency>
  <groupId>org.springframework.data</groupId>
  <artifactId>spring-data-keyvalue</artifactId>
  <version>${version}</version>
</dependency>
----

For snapshot versions, make sure you include the spring snapshots repository:

[source, xml]
----
<repositories>
  <repository>
    <id>spring-libs-snapshot</id>
    <url>http://repo.spring.io/libs-snapshot</url>
  </repository>
</repositories>
----

The `ConcurrentHashMap` based default configuration looks like this:

[source, java]
----
@Configuration
@EnableMapRepositories("com.acme.repositories")
class AppConfig { … }
----

NOTE: it is possible to change the used `java.util.Map` implementation via `@EnableMapRepositories(mapType=….class)`.

Create the domain type and use `@KeySpace` to explicitly group values into one region. By default, the type class name is used.

[source, java]
----
@KeySpace("user")
class User {

  @Id String uuid;
  String firstname;
}
----

Create a repository interface in `com.acme.repositories`:

[source, java]
----
public interface UserRepository extends CrudRepository<User, String> {
  List<String> findByLastname(String lastname);
}
----

## QueryDSL

To use Querydsl with Spring Data KeyValue repositories, `com.mysema.querydsl:querydsl-collections:3.6.0` (or better) needs to be present on the classpath. Just add `QueryDslPredicateExecutor` to the repository definition and use `com.mysema.query.types.Predicate` to define the query.


## Tips
To have the maximum performance we encourage you to use the latest Spring 4.1.x or better release with compiled SpEL expressions enabled.

[source, bash]
----
-Dspring.expression.compiler.mode=IMMEDIATE
----


## Contributing to Spring Data Key Value

Here are some ways for you to get involved in the community:

* Get involved with the Spring community by helping out on http://stackoverflow.com/questions/tagged/spring-data-keyvalue[stackoverflow] by responding to questions and joining the debate.
* Create https://jira.spring.io/browse/DATAKV[JIRA] tickets for bugs and new features and comment and vote on the ones that you are interested in.
* Github is for social coding: if you want to write code, we encourage contributions through pull requests from http://help.github.com/forking[forks of this repository]. If you want to contribute code this way, please reference a JIRA ticket as well covering the specific issue you are addressing.
* Watch for upcoming articles on Spring by http://spring.io/blog[subscribing] to spring.io.

Before we accept a non-trivial patch or pull request we will need you to https://cla.pivotal.io/sign/spring[sign the Contributor License Agreement]. Signing the contributor’s agreement does not grant anyone commit rights to the main repository, but it does mean that we can accept your contributions, and you will get an author credit if we do. If you forget to do so, you'll be reminded when you submit a pull request.
 Active contributors might be asked to join the core team, and given the ability to merge pull requests.