DATAMONGO-1693 - Support collation in ReactiveMongoTemplate.createCollection.

We now consider Collation via CollectionOptions when creating collections using ReactiveMongoTemplate.createCollection.

Original Pull Request: #462.

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/ReactiveMongoTemplate.java

@@ -1629,6 +1629,7 @@ public class ReactiveMongoTemplate implements ReactiveMongoOperations, Applicati
 			collectionOptions.getCapped().ifPresent(result::capped);
 			collectionOptions.getSize().ifPresent(result::sizeInBytes);
 			collectionOptions.getMaxDocuments().ifPresent(result::maxDocuments);
+			collectionOptions.getCollation().map(Collation::toMongoCollation).ifPresent(result::collation);
 		}
 		return result;
 	}

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/ReactiveMongoTemplateCollationTests.java

@@ -0,0 +1,105 @@
+/*
+ * Copyright 2017 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 org.springframework.data.mongodb.core;
+
+import static org.assertj.core.api.Assertions.*;
+
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+import reactor.test.StepVerifier;
+
+import java.util.List;
+
+import org.bson.Document;
+import org.junit.Before;
+import org.junit.ClassRule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.data.mongodb.config.AbstractReactiveMongoConfiguration;
+import org.springframework.data.mongodb.test.util.MongoVersionRule;
+import org.springframework.data.util.Version;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+
+import com.mongodb.reactivestreams.client.MongoClients;
+
+/**
+ * @author Mark Paluch
+ */
+@RunWith(SpringJUnit4ClassRunner.class)
+public class ReactiveMongoTemplateCollationTests {
+
+	public static @ClassRule MongoVersionRule REQUIRES_AT_LEAST_3_4_0 = MongoVersionRule.atLeast(Version.parse("3.4.0"));
+	public static final String COLLECTION_NAME = "collation-1";
+
+	@Configuration
+	static class Config extends AbstractReactiveMongoConfiguration {
+
+		@Override
+		public com.mongodb.reactivestreams.client.MongoClient mongoClient() {
+			return MongoClients.create();
+		}
+
+		@Override
+		protected String getDatabaseName() {
+			return "collation-tests";
+		}
+	}
+
+	@Autowired ReactiveMongoTemplate template;
+
+	@Before
+	public void setUp() {
+		StepVerifier.create(template.dropCollection(COLLECTION_NAME)).verifyComplete();
+	}
+
+	@Test // DATAMONGO-1693
+	public void createCollectionWithCollation() {
+
+		StepVerifier.create(template.createCollection(COLLECTION_NAME, CollectionOptions.just(Collation.of("en_US")))) //
+				.expectNextCount(1) //
+				.verifyComplete();
+
+		Mono<Document> collation = getCollationInfo(COLLECTION_NAME);
+		StepVerifier.create(collation) //
+				.consumeNextWith(document -> assertThat(document.get("locale")).isEqualTo("en_US")) //
+				.verifyComplete();
+
+	}
+
+	private Mono<Document> getCollationInfo(String collectionName) {
+
+		return getCollectionInfo(collectionName) //
+				.map(it -> it.get("options", Document.class)) //
+				.map(it -> it.get("collation", Document.class));
+	}
+
+	@SuppressWarnings("unchecked")
+	private Mono<Document> getCollectionInfo(String collectionName) {
+
+		return template.execute(db -> {
+
+			return Flux
+					.from(db.runCommand(new Document() //
+							.append("listCollections", 1) //
+							.append("filter", new Document("name", collectionName)))) //
+					.map(it -> it.get("cursor", Document.class))
+					.flatMapIterable(it -> (List<Document>) it.get("firstBatch", List.class));
+		}).next();
+	}
+
+}