DATACOUCH-161 - Improve multitemplate mapping configuration

The configuration step made it look like a new mapping was necessary in overrides, whereas it is actually possible and clearer to mutate the base mapping.

Added a convenience method to get the MappingContext from the repository mapping.

src/main/java/org/springframework/data/couchbase/config/AbstractCouchbaseConfiguration.java

@@ -161,12 +161,27 @@ public abstract class AbstractCouchbaseConfiguration {
   /**
    * Creates the {@link RepositoryOperationsMapping} bean which will be used by the framework to choose which
    * {@link CouchbaseOperations} should back which {@link CouchbaseRepository}.
+   * Override {@link #configureRepositoryOperationsMapping(RepositoryOperationsMapping)} in order to customize this.
    *
    * @throws Exception
    */
   @Bean(name = BeanNames.REPO_OPERATIONS_MAPPING)
   public RepositoryOperationsMapping repositoryOperationsMapping() throws  Exception {
-    return new RepositoryOperationsMapping(couchbaseTemplate());
+    //create a base mapping that associates all repositories to the default template
+    RepositoryOperationsMapping baseMapping = new RepositoryOperationsMapping(couchbaseTemplate());
+    //let the user tune it
+    configureRepositoryOperationsMapping(baseMapping);
+    return baseMapping;
+  }
+
+  /**
+   * In order to customize the mapping between repositories/entity types to couchbase templates,
+   * use the provided mapping's api (eg. in order to have different buckets backing different repositories).
+   *
+   * @param mapping the default mapping (will associate all repositories to the default template).
+   */
+  protected void configureRepositoryOperationsMapping(RepositoryOperationsMapping mapping) {
+    //NO_OP
   }
 
   /**

src/main/java/org/springframework/data/couchbase/repository/config/RepositoryOperationsMapping.java

@@ -20,6 +20,10 @@ import java.util.HashMap;
 import java.util.Map;
 
 import org.springframework.data.couchbase.core.CouchbaseOperations;
+import org.springframework.data.couchbase.core.mapping.CouchbasePersistentEntity;
+import org.springframework.data.couchbase.core.mapping.CouchbasePersistentProperty;
+import org.springframework.data.mapping.context.MappingContext;
+import org.springframework.util.Assert;
 
 /**
  * A utility class for configuration allowing to tell which {@link CouchbaseOperations} should be backing
@@ -33,12 +37,14 @@ public class RepositoryOperationsMapping {
   private Map<String, CouchbaseOperations> byRepository = new HashMap<String, CouchbaseOperations>();
   private Map<String, CouchbaseOperations> byEntity = new HashMap<String, CouchbaseOperations>();
 
+
   /**
    * Creates a new mapping, setting the default fallback to use by otherwise non mapped repositories.
    *
    * @param defaultOperations the default fallback couchbase operations.
    */
   public RepositoryOperationsMapping(CouchbaseOperations defaultOperations) {
+    Assert.notNull(defaultOperations);
     this.defaultOperations = defaultOperations;
   }
 
@@ -49,6 +55,7 @@ public class RepositoryOperationsMapping {
    * @return the mapping, for chaining.
    */
   public RepositoryOperationsMapping setDefault(CouchbaseOperations aDefault) {
+    Assert.notNull(aDefault);
     this.defaultOperations = aDefault;
     return this;
   }
@@ -85,6 +92,15 @@ public class RepositoryOperationsMapping {
     return defaultOperations;
   }
 
+  /**
+   * Get the {@link MappingContext} to use in repositories. It is extracted from the default {@link CouchbaseOperations}.
+   *
+   *  @return the mapping context.
+   */
+  public MappingContext<? extends CouchbasePersistentEntity<?>, CouchbasePersistentProperty> getMappingContext() {
+    return defaultOperations.getConverter().getMappingContext();
+  }
+
   /**
    * Given a repository interface and its domain type, resolves which {@link CouchbaseOperations} it should be backed with.
    *

src/main/java/org/springframework/data/couchbase/repository/support/CouchbaseRepositoryFactory.java

@@ -91,7 +91,7 @@ public class CouchbaseRepositoryFactory extends RepositoryFactorySupport {
 
     this.couchbaseOperationsMapping = couchbaseOperationsMapping;
     this.indexManager = indexManager;
-    mappingContext = this.couchbaseOperationsMapping.getDefault().getConverter().getMappingContext();
+    mappingContext = this.couchbaseOperationsMapping.getMappingContext();
     viewPostProcessor = ViewPostProcessor.INSTANCE;
 
     addRepositoryProxyPostProcessor(viewPostProcessor);
@@ -157,7 +157,6 @@ public class CouchbaseRepositoryFactory extends RepositoryFactorySupport {
 
     //for other repos, they might also need N1QL if they don't have only @View methods
     if (!needsN1ql) {
-
       for (Method method : metadata.getQueryMethods()) {
 
         boolean hasN1ql = AnnotationUtils.findAnnotation(method, Query.class) != null;

src/main/java/org/springframework/data/couchbase/repository/support/CouchbaseRepositoryFactoryBean.java

@@ -54,7 +54,7 @@ public class CouchbaseRepositoryFactoryBean<T extends Repository<S, ID>, S, ID e
 
   public void setCouchbaseOperationsMapping(final RepositoryOperationsMapping mapping) {
     this.operationsMapping = mapping;
-    setMappingContext(operationsMapping.getDefault().getConverter().getMappingContext());
+    setMappingContext(operationsMapping.getMappingContext());
   }
 
   /**