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# Spring Data Couchbase 3.0.x
`Spring-Data Couchbase 3.0.x` is the Spring Data connector for the `Couchbase Java SDK 2.x` generation.

Both the SDK and this Spring Data community project are major version changes with lots of differences from their
respective previous versions.

Notably, this version is compatible with `Couchbase Server 4.0`, bringing support for the `N1QL` query language.

# Spring Data Couchbase

The primary goal of the [Spring Data](http://www.springsource.org/spring-data) project is to make it easier to build
Spring-powered applications that use new data access technologies such as non-relational databases, map-reduce
frameworks, and cloud based data services.

The Spring Data Couchbase project aims to provide a familiar and consistent Spring-based programming model for Couchbase
Server as a document database and cache while retaining store-specific features and capabilities. Key functional areas
of Spring Data Couchbase are a POJO centric model for interacting with a Couchbase Server Bucket and easily writing a
repository style data access layer.

## Getting Help

For a comprehensive treatment of all the Spring Data Couchbase features, please refer to:

* the [User Guide](http://docs.spring.io/spring-data/couchbase/docs/current/reference/html/) for the current GA version.
* the [JavaDocs](http://docs.spring.io/spring-data/couchbase/docs/current/api/) have extensive comments
  in them as well.
* for more detailed questions, use the [StackOverflow `spring-data-couchbase` tag](http://stackoverflow.com/questions/tagged/spring-data-couchbase)
or Couchbase's own [forums](https://forums.couchbase.com/c/java-sdk).

If you are new to Spring as well as to Spring Data, look for information about
[Spring projects](http://www.springsource.org/projects).


## Quick Start

### Maven configuration

Add the Maven dependency:

```xml
<dependency>
  <groupId>org.springframework.data</groupId>
  <artifactId>spring-data-couchbase</artifactId>
  <version>${version}.RELEASE</version>
</dependency>
```

If you'd rather like the latest snapshots of the upcoming major version, use our Maven snapshot repository and declare
the appropriate dependency version.

```xml
<dependency>
  <groupId>org.springframework.data</groupId>
  <artifactId>spring-data-couchbase</artifactId>
  <version>${version}.BUILD-SNAPSHOT</version>
</dependency>

<repository>
  <id>spring-libs-snapshot</id>
  <name>Spring Snapshot Repository</name>
  <url>http://repo.spring.io/libs-snapshot</url>
</repository>
```

### CouchbaseTemplate

CouchbaseTemplate is the central support class for Couchbase database operations. It provides:

* Basic POJO mapping support to and from JSON (by default through Jackson)
* Convenience methods to interact with the store (insert object, update objects) and Couchbase specific ones
* Exception translation into Spring's [technology agnostic DAO exception hierarchy](http://docs.spring.io/spring/docs/current/spring-framework-reference/html/dao.html#dao-exceptions).

### Spring Data Repositories

To simplify the creation of data repositories Spring Data Couchbase provides a generic repository programming model. It
will automatically create a repository proxy for you that adds implementations of finder methods you specify on an
interface.

To create a repository on top of a `UserInfo` entity, all you need to write is:

```java
public interface UserRepository extends CrudRepository<UserInfo, String> {

  /**
   * Return all users emitted by the view userInfo/adults
   */
  @View
  List<UserInfo> findAdults();
  
  /**
   * Find all users matching the last name.
   */
  @View(viewName="lastNames")     
  List<UserInfo> findByLastname(String lastName);
  
  /**
   * Find all the users whose first name contains the word.
   */
  List<UserInfo> findByFirstnameContains(String word);

}
```

Once you get a reference to that repository bean, you'll find a lot of methods that make it very easy to work with this
entity. In addition to the ones provided through the `CrudRepository`, you can add your own methods as well.

In general, every CRUD method that does not depend on a single key (like `findById`) needs a backing View, `all` on the
server side (the design document is by default expected to be the uncapitalized name of the entity, like `userInfo`).

## Custom Repository Methods and Views
Finder methods you define, if annotated with `@View`, also are backed by views. Either you want to return all items from
these views and you can let the method name reflect the view name (like in `findAdults()`, where it'll expect an
`adults` view), or provide simple criteria (you explicitly specify the `viewName` and let the method name determine your
criteria, like in `findByLastname`).

In the example above, it assumes you have a view named `findByLastname` in the `userInfo` design document. You
can customize the view and design document name through the `@View` annotation. Also make sure you publish them into
production before accessing it.

This is an example view for the `findByLastname` method:

```javascript
function (doc, meta) {
  if(doc._class == "com.example.entity.UserInfo" && doc.lastname) {
    emit(doc.lastname, null);
  }
}
```

If you want to use more query parameters than what is supported through query derivation (see `ViewQueryCreator`), you
need to provide the implementation of the finder methods yourself and use the underlying `CouchbaseTemplate`.

The `all` view that backs CRUD `findAll()` and `count()` needs to look like this (and do not forget the `_count` reduce
function):

```javascript
function (doc, meta) {
  if(doc._class == "com.example.entity.UserInfo") {
    emit(null, null);
  }
}
```

Alternatively, if view creation isn't too costly, you can ask the framework to create it automatically by annotating the
repository with `@ViewIndexed(designDoc = "userInfo", viewName = "all")`.

## N1QL and Query Derivation
With the introduction of `N1QL`, Couchbase can now better support query derivation (the mechanism that allows you to
add custom methods that will automatically be implemented as a N1QL query derived from the method's name).

This is the default repository query mechanism, so the associated `@Query` annotation is optional. Here is what it looks
like:

```java
public interface UserRepository extends CrudRepository<UserInfo, String> {

  /**
   * Advanced querying with N1QL derivation
   */
  @Query
  List<UserInfo> findByLastnameEqualsIgnoreCaseAndFirstnameStartsWithAndIsAdultTrue(String lastName, String fnamePrefix);
}
```

For instance, calling `find...("Locke", "J")` will get resolved to this N1QL WHERE clause (similar to SQL):

```sql
...WHERE LOWER(lastname) = LOWER("Locke") AND firstname LIKE "J%" AND isAdult = TRUE;
```

You can alternatively write the statement yourself inside the `@Query` annotation, using the `$SELECT_ENTITY$`
placeholder to make sure all necessary fields and metadata are selected by N1QL:

```java
@Query("$SELECT_ENTITY$ WHERE firstname LIKE "%ck%")
List<UserInfo> findPatrickAndJackAmongOthers();

@Query("$SELECT_ENTITY$ WHERE firstname LIKE $1")
List<UserInfo> findUsersWithTheirFirstnameLike(String likePattern);
```

N1QL needs at least a generic purpose `N1QL primary index` to work with, and can make use of a more entity
type-specific `N1QL secondary index`. You can create both automatically (provided you are confident this
is not to much of a cost) by annotating a repository with `@N1qlPrimaryIndexed` and/or `@N1qlSecondaryIndexed`. 

## Using The Repository

Extending `CrudRepository` causes CRUD methods being pulled into the interface so that you can easily save and find
single entities and collections of them.

You can have Spring automatically create a proxy for the interface by using the following JavaConfig:

```java
@Configuration
@EnableCouchbaseRepositories
public class Config extends AbstractCouchbaseConfiguration {

	@Override
	protected List<String> getBootstrapHosts() {
		return Arrays.asList("host1", "host2");
	}

	@Override
	protected String getBucketName() {
		return "default";
	}

	@Override
	protected String getBucketPassword() {
		return "";
	}
}
```

This sets up a connection to a Couchbase cluster and enables the detection of Spring Data repositories (through
`@EnableCouchbaseRepositories`). The same configuration would look like this in XML:

```xml
<couchbase:cluster id="cb-first">
  <couchbase:node>localhost</couchbase:node>
</couchbase:cluster>

<couchbase:bucket id="cb-bucket-first" cluster-ref="cb-first" bucket="default" password="" />

<couchbase:template id="cb-template-first"  bucket-ref="cb-bucket-first" />

<couchbase:repositories couchbase-template-ref="cb-template-first" />
```

This will find the repository interface and register a proxy object in the container. You can use it as shown below:

```java
@Service
public class MyService {

  private final UserRepository userRepository;

    @Autowired
  public MyService(UserRepository userRepository) {
    this.userRepository = userRepository;
  }

  public void doWork() {
    userRepository.deleteAll();

    UserInfo userInfo = new UserInfo();
    UserInfo.setLastname("Jackson");

    UserInfo = userRepository.save(userInfo);

    List<UserInfo> allJacksons = userRepository.findByLastname("Jackson");
  }
}
```


## Contributing to Spring Data

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

* Get involved with the Spring community on Stack Overflow.  Please help out on the
  [`spring-data`](http://stackoverflow.com/questions/tagged/spring-data) and
  [`spring-data-couchbase`](http://stackoverflow.com/questions/tagged/spring-data-couchbase) tags by responding to
  questions.
* Create [JIRA](jira.spring.io/browse/DATACOUCH) `DATACOUCH` 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
  [forks of this repository](http://help.github.com/forking/). 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 [subscribing](http://assets.spring.io/drupal/node/feed.xml) to spring.io RSS feed.

BBefore we accept a non-trivial patch or pull request we will need you to [sign the Contributor License Agreement](https://cla.pivotal.io/sign/spring). 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.