#144 - Make use of the dedicated configuration API for EntityLookups.

Rather than declaring a dedicated EntityLookup bean instance we now use the configuration API introduced on RepositoryRestConfiguration to define the identifier and lookup mapping.

Tweaked readme accordingly.

rest/uri-customization/readme.adoc

@@ -1,6 +1,36 @@
 = Spring Data REST URI customizations
 
-This example shows how to customize which property of the domain type shall be used to create URIs for item resources. This is achieved by implementing an `EntityLookup` and declaring it as Spring bean:
+This example shows how to customize which property of the domain type shall be used to create URIs for item resources.
+
+When using Java 8, this is as easy as registering the mapping operations on Spring Data RESTs `RepositoryRestConfiguration`:
+
+[source, java]
+----
+@Component
+public class SpringDataRestCustomization extends RepositoryRestConfigurerAdapter {
+
+  @Override
+  public void configureRepositoryRestConfiguration(RepositoryRestConfiguration config) {
+
+    config.withCustomEntityLookup().//
+      forRepository(UserRepository.class, User::getUsername, UserRepository::findByUsername);
+  }
+}
+----
+
+As you can see the `EntityLookupRegistrar` obtained via `RepositoryrestConfiguration.withCustomEntityLookup()` takes two method references.
+The first one defines the identifier mapping, the second one defines how to look up the entity using the repository.
+The customization could also be defined in a slightly more explicit way like this:
+
+[source, java]
+----
+config.withCustomEntityLookup().
+  forRepository(UserRepository.class).
+  withIdMapping(User::getUsername).
+  withLookup(UserRepository::findByUsername);
+----
+
+In non-Java 8 environments the method references would have to be replaced with a quite verbose anonymous inner class, so that it's probably easier to implement `EntityLookup` explixitly and declare it as Spring bean:
 
 [source, java]
 ----
@@ -8,17 +38,17 @@ This example shows how to customize which property of the domain type shall be u
 @RequiredArgsConstructor(onConstructor = @__(@Autowired) )
 public class UserEntityLookup extends EntityLookupSupport<User> {
 
-    private final @NonNull UserRepository repository;
+  private final @NonNull UserRepository repository;
 
-    @Override
-    public Serializable getResourceIdentifier(User entity) {
-        return entity.getUsername();
-    }
+  @Override
+  public Serializable getResourceIdentifier(User entity) {
+     return entity.getUsername();
+  }
 
-    @Override
-    public Object lookupEntity(Serializable id) {
-        return repository.findByUsername(id.toString());
-    }
+  @Override
+  public Object lookupEntity(Serializable id) {
+    return repository.findByUsername(id.toString());
+  }
 }
 ----
 

rest/uri-customization/src/main/java/example/springdata/rest/uris/SpringDataRestCustomization.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2015 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package example.springdata.rest.uris;
+
+import org.springframework.data.rest.core.config.RepositoryRestConfiguration;
+import org.springframework.data.rest.webmvc.config.RepositoryRestConfigurerAdapter;
+import org.springframework.stereotype.Component;
+
+/**
+ * Spring Data {@link RepositoryRestConfiguration} to customize the identifier mapping for {@link User}s.
+ * 
+ * @author Oliver Gierke
+ */
+@Component
+public class SpringDataRestCustomization extends RepositoryRestConfigurerAdapter {
+
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.data.rest.webmvc.config.RepositoryRestConfigurerAdapter#configureRepositoryRestConfiguration(org.springframework.data.rest.core.config.RepositoryRestConfiguration)
+	 */
+	@Override
+	public void configureRepositoryRestConfiguration(RepositoryRestConfiguration config) {
+
+		config.withCustomEntityLookup().//
+				forRepository(UserRepository.class, User::getUsername, UserRepository::findByUsername);
+	}
+}

rest/uri-customization/src/main/java/example/springdata/rest/uris/UserEntityLookup.java

@@ -23,15 +23,16 @@ import java.io.Serializable;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.data.rest.core.support.EntityLookup;
 import org.springframework.data.rest.core.support.EntityLookupSupport;
-import org.springframework.stereotype.Component;
 
 /**
  * Custom {@link EntityLookup} to replace the usage of the database identifier in item resource URIs with the username
- * property of the {@link User}.
+ * property of the {@link User}. This one is not really used out of the box as it's not a Spring bean. It's just a
+ * sample of how to deploy a customization in non-Java 8 environments which can't use the fluent API in use in
+ * {@link SpringDataRestCustomization}.
  * 
  * @author Oliver Gierke
+ * @see SpringDataRestCustomization#configureRepositoryRestConfiguration(org.springframework.data.rest.core.config.RepositoryRestConfiguration)
  */
-@Component
 @RequiredArgsConstructor(onConstructor = @__(@Autowired) )
 public class UserEntityLookup extends EntityLookupSupport<User> {