DATAMONGO-1919 - Allow reactive-only usage of ReactiveMongoTemplate.

We now support reactive-only usage of Spring Data MongoDB without the need to use the synchronous driver or even having it on the class path. We conditionally register CodeWScope/CodeWithScope types that are bundled with the particular driver distributions.

NoOpDbRefResolver is now a top-level type to be used with a reactive-only MongoMappingContext.

Original Pull Request: #572

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/config/AbstractReactiveMongoConfiguration.java

@@ -22,6 +22,7 @@ import org.springframework.data.mongodb.core.ReactiveMongoOperations;
 import org.springframework.data.mongodb.core.ReactiveMongoTemplate;
 import org.springframework.data.mongodb.core.SimpleReactiveMongoDatabaseFactory;
 import org.springframework.data.mongodb.core.convert.MappingMongoConverter;
+import org.springframework.data.mongodb.core.convert.NoOpDbRefResolver;
 
 import com.mongodb.reactivestreams.client.MongoClient;
 
@@ -80,7 +81,7 @@ public abstract class AbstractReactiveMongoConfiguration extends MongoConfigurat
 	@Bean
 	public MappingMongoConverter mappingMongoConverter() throws Exception {
 
-		MappingMongoConverter converter = new MappingMongoConverter(ReactiveMongoTemplate.NO_OP_REF_RESOLVER,
+		MappingMongoConverter converter = new MappingMongoConverter(NoOpDbRefResolver.INSTANCE,
 				mongoMappingContext());
 		converter.setCustomConversions(customConversions());
 

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

@@ -32,8 +32,6 @@ import java.util.function.Consumer;
 import java.util.function.Function;
 import java.util.stream.Collectors;
 
-import javax.annotation.Nonnull;
-
 import org.bson.BsonTimestamp;
 import org.bson.BsonValue;
 import org.bson.Document;
@@ -77,7 +75,16 @@ import org.springframework.data.mongodb.core.aggregation.AggregationOptions;
 import org.springframework.data.mongodb.core.aggregation.PrefixingDelegatingAggregationOperationContext;
 import org.springframework.data.mongodb.core.aggregation.TypeBasedAggregationOperationContext;
 import org.springframework.data.mongodb.core.aggregation.TypedAggregation;
-import org.springframework.data.mongodb.core.convert.*;
+import org.springframework.data.mongodb.core.convert.DbRefResolver;
+import org.springframework.data.mongodb.core.convert.JsonSchemaMapper;
+import org.springframework.data.mongodb.core.convert.MappingMongoConverter;
+import org.springframework.data.mongodb.core.convert.MongoConverter;
+import org.springframework.data.mongodb.core.convert.MongoCustomConversions;
+import org.springframework.data.mongodb.core.convert.MongoJsonSchemaMapper;
+import org.springframework.data.mongodb.core.convert.MongoWriter;
+import org.springframework.data.mongodb.core.convert.NoOpDbRefResolver;
+import org.springframework.data.mongodb.core.convert.QueryMapper;
+import org.springframework.data.mongodb.core.convert.UpdateMapper;
 import org.springframework.data.mongodb.core.index.MongoMappingEventPublisher;
 import org.springframework.data.mongodb.core.index.ReactiveIndexOperations;
 import org.springframework.data.mongodb.core.index.ReactiveMongoPersistentEntityIndexCreator;
@@ -96,7 +103,6 @@ import org.springframework.data.mongodb.core.mapping.event.MongoMappingEvent;
 import org.springframework.data.mongodb.core.mapreduce.MapReduceOptions;
 import org.springframework.data.mongodb.core.query.Collation;
 import org.springframework.data.mongodb.core.query.Criteria;
-import org.springframework.data.mongodb.core.query.CriteriaDefinition;
 import org.springframework.data.mongodb.core.query.Meta;
 import org.springframework.data.mongodb.core.query.NearQuery;
 import org.springframework.data.mongodb.core.query.Query;
@@ -119,7 +125,6 @@ import com.mongodb.ClientSessionOptions;
 import com.mongodb.CursorType;
 import com.mongodb.DBCollection;
 import com.mongodb.DBCursor;
-import com.mongodb.DBRef;
 import com.mongodb.Mongo;
 import com.mongodb.MongoException;
 import com.mongodb.ReadPreference;
@@ -156,7 +161,7 @@ import com.mongodb.util.JSONParseException;
  */
 public class ReactiveMongoTemplate implements ReactiveMongoOperations, ApplicationContextAware {
 
-	public static final DbRefResolver NO_OP_REF_RESOLVER = new NoOpDbRefResolver();
+	public static final DbRefResolver NO_OP_REF_RESOLVER = NoOpDbRefResolver.INSTANCE;
 
 	private static final Logger LOGGER = LoggerFactory.getLogger(ReactiveMongoTemplate.class);
 	private static final String ID_FIELD = "_id";
@@ -3287,54 +3292,6 @@ public class ReactiveMongoTemplate implements ReactiveMongoOperations, Applicati
 		return new ArrayList<>(documents);
 	}
 
-	/**
-	 * No-Operation {@link org.springframework.data.mongodb.core.mapping.DBRef} resolver.
-	 *
-	 * @author Mark Paluch
-	 */
-	static class NoOpDbRefResolver implements DbRefResolver {
-
-		/*
-		 * (non-Javadoc)
-		 * @see org.springframework.data.mongodb.core.convert.DbRefResolver#resolveDbRef(org.springframework.data.mongodb.core.mapping.MongoPersistentProperty, org.springframework.data.mongodb.core.convert.DbRefResolverCallback)
-		 */
-		@Override
-		@Nullable
-		public Object resolveDbRef(@Nonnull MongoPersistentProperty property, @Nonnull DBRef dbref,
-				@Nonnull DbRefResolverCallback callback, @Nonnull DbRefProxyHandler proxyHandler) {
-			return null;
-		}
-
-		/*
-		 * (non-Javadoc)
-		 * @see org.springframework.data.mongodb.core.convert.DbRefResolver#created(org.springframework.data.mongodb.core.mapping.MongoPersistentProperty, org.springframework.data.mongodb.core.mapping.MongoPersistentEntity, java.lang.Object)
-		 */
-		@Override
-		@Nullable
-		public DBRef createDbRef(org.springframework.data.mongodb.core.mapping.DBRef annotation,
-				MongoPersistentEntity<?> entity, Object id) {
-			return null;
-		}
-
-		/*
-		 * (non-Javadoc)
-		 * @see org.springframework.data.mongodb.core.convert.DbRefResolver#fetch(com.mongodb.DBRef)
-		 */
-		@Override
-		public Document fetch(DBRef dbRef) {
-			return null;
-		}
-
-		/*
-		 * (non-Javadoc)
-		 * @see org.springframework.data.mongodb.core.convert.DbRefResolver#bulkFetch(java.util.List)
-		 */
-		@Override
-		public List<Document> bulkFetch(List<DBRef> dbRefs) {
-			return Collections.emptyList();
-		}
-	}
-
 	/**
 	 * {@link MongoTemplate} extension bound to a specific {@link ClientSession} that is applied when interacting with the
 	 * server through the driver API.

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

@@ -22,6 +22,7 @@ import org.springframework.dao.InvalidDataAccessApiUsageException;
 import org.springframework.data.mongodb.core.mapping.MongoPersistentEntity;
 import org.springframework.data.mongodb.core.mapping.MongoPersistentProperty;
 import org.springframework.lang.Nullable;
+import org.springframework.util.StringUtils;
 
 import com.mongodb.DBRef;
 
@@ -59,9 +60,15 @@ public interface DbRefResolver {
 	 * @param id will never be {@literal null}.
 	 * @return
 	 */
-	DBRef createDbRef(@Nullable org.springframework.data.mongodb.core.mapping.DBRef annotation,
-			MongoPersistentEntity<?> entity,
-			Object id);
+	default DBRef createDbRef(@Nullable org.springframework.data.mongodb.core.mapping.DBRef annotation,
+			MongoPersistentEntity<?> entity, Object id) {
+
+		if (annotation != null && StringUtils.hasText(annotation.db())) {
+			return new DBRef(annotation.db(), entity.getCollection(), id);
+		}
+
+		return new DBRef(entity.getCollection(), id);
+	}
 
 	/**
 	 * Actually loads the {@link DBRef} from the datasource.

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

@@ -104,21 +104,6 @@ public class DefaultDbRefResolver implements DbRefResolver {
 		return callback.resolve(property);
 	}
 
-	/*
-	 * (non-Javadoc)
-	 * @see org.springframework.data.mongodb.core.convert.DbRefResolver#created(org.springframework.data.mongodb.core.mapping.MongoPersistentProperty, org.springframework.data.mongodb.core.mapping.MongoPersistentEntity, java.lang.Object)
-	 */
-	@Override
-	public DBRef createDbRef(@Nullable org.springframework.data.mongodb.core.mapping.DBRef annotation,
-			MongoPersistentEntity<?> entity, Object id) {
-
-		if (annotation != null && StringUtils.hasText(annotation.db())) {
-			return new DBRef(annotation.db(), entity.getCollection(), id);
-		}
-
-		return new DBRef(entity.getCollection(), id);
-	}
-
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.mongodb.core.convert.DbRefResolver#fetch(com.mongodb.DBRef)

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

@@ -0,0 +1,69 @@
+/*
+ * Copyright 2018 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.convert;
+
+import java.util.List;
+
+import javax.annotation.Nonnull;
+
+import org.bson.Document;
+import org.springframework.data.mongodb.core.mapping.MongoPersistentEntity;
+import org.springframework.data.mongodb.core.mapping.MongoPersistentProperty;
+import org.springframework.lang.Nullable;
+import org.springframework.util.StringUtils;
+
+import com.mongodb.DBRef;
+
+/**
+ * No-Operation {@link org.springframework.data.mongodb.core.mapping.DBRef} resolver throwing
+ * {@link UnsupportedOperationException} when attempting to resolve database references.
+ *
+ * @author Mark Paluch
+ * @since 2.1
+ */
+public enum NoOpDbRefResolver implements DbRefResolver {
+
+	INSTANCE;
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.convert.DbRefResolver#resolveDbRef(org.springframework.data.mongodb.core.mapping.MongoPersistentProperty, org.springframework.data.mongodb.core.convert.DbRefResolverCallback)
+	 */
+	@Override
+	@Nullable
+	public Object resolveDbRef(@Nonnull MongoPersistentProperty property, @Nonnull DBRef dbref,
+			@Nonnull DbRefResolverCallback callback, @Nonnull DbRefProxyHandler proxyHandler) {
+		throw new UnsupportedOperationException("DBRef resolution not supported!");
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.convert.DbRefResolver#fetch(com.mongodb.DBRef)
+	 */
+	@Override
+	public Document fetch(DBRef dbRef) {
+		throw new UnsupportedOperationException("DBRef resolution not supported!");
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.convert.DbRefResolver#bulkFetch(java.util.List)
+	 */
+	@Override
+	public List<Document> bulkFetch(List<DBRef> dbRefs) {
+		throw new UnsupportedOperationException("DBRef resolution not supported!");
+	}
+}

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

@@ -24,7 +24,6 @@ import java.util.regex.Pattern;
 
 import org.bson.BsonObjectId;
 import org.bson.types.Binary;
-import org.bson.types.CodeWScope;
 import org.bson.types.ObjectId;
 import org.springframework.data.mapping.model.SimpleTypeHolder;
 import org.springframework.data.mongodb.util.MongoClientVersion;
@@ -37,6 +36,7 @@ import com.mongodb.DBRef;
  *
  * @author Oliver Gierke
  * @author Christoph Strobl
+ * @author Mark Paluch
  */
 public abstract class MongoSimpleTypes {
 
@@ -53,15 +53,21 @@ public abstract class MongoSimpleTypes {
 		simpleTypes.add(DBRef.class);
 		simpleTypes.add(ObjectId.class);
 		simpleTypes.add(BsonObjectId.class);
-		simpleTypes.add(CodeWScope.class);
 		simpleTypes.add(org.bson.Document.class);
 		simpleTypes.add(Pattern.class);
 		simpleTypes.add(Binary.class);
 		simpleTypes.add(UUID.class);
 
+		if (ClassUtils.isPresent("org.bson.types.CodeWScope", MongoSimpleTypes.class.getClassLoader())) {
+			simpleTypes.add(resolveClassName("org.bson.types.CodeWScope"));
+		}
+
+		if (ClassUtils.isPresent("org.bson.types.CodeWithScope", MongoSimpleTypes.class.getClassLoader())) {
+			simpleTypes.add(resolveClassName("org.bson.types.CodeWithScope"));
+		}
+
 		if (MongoClientVersion.isMongo34Driver()) {
-			simpleTypes
-					.add(ClassUtils.resolveClassName("org.bson.types.Decimal128", MongoSimpleTypes.class.getClassLoader()));
+			simpleTypes.add(resolveClassName("org.bson.types.Decimal128"));
 		}
 
 		MONGO_SIMPLE_TYPES = Collections.unmodifiableSet(simpleTypes);
@@ -71,4 +77,8 @@ public abstract class MongoSimpleTypes {
 	public static final SimpleTypeHolder HOLDER = new SimpleTypeHolder(MONGO_SIMPLE_TYPES, true);
 
 	private MongoSimpleTypes() {}
+
+	private static Class<?> resolveClassName(String className) {
+		return ClassUtils.resolveClassName(className, MongoSimpleTypes.class.getClassLoader());
+	}
 }

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

@@ -41,8 +41,8 @@ import org.reactivestreams.Publisher;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.data.annotation.Id;
 import org.springframework.data.mongodb.core.MongoTemplateUnitTests.AutogenerateableId;
-import org.springframework.data.mongodb.core.ReactiveMongoTemplate.NoOpDbRefResolver;
 import org.springframework.data.mongodb.core.convert.MappingMongoConverter;
+import org.springframework.data.mongodb.core.convert.NoOpDbRefResolver;
 import org.springframework.data.mongodb.core.mapping.Field;
 import org.springframework.data.mongodb.core.mapping.MongoMappingContext;
 import org.springframework.data.mongodb.core.query.BasicQuery;
@@ -107,7 +107,7 @@ public class ReactiveMongoTemplateUnitTests {
 		when(aggregatePublisher.first()).thenReturn(findPublisher);
 
 		this.mappingContext = new MongoMappingContext();
-		this.converter = new MappingMongoConverter(new NoOpDbRefResolver(), mappingContext);
+		this.converter = new MappingMongoConverter(NoOpDbRefResolver.INSTANCE, mappingContext);
 		this.template = new ReactiveMongoTemplate(factory, converter);
 
 	}

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

@@ -39,10 +39,10 @@ import org.reactivestreams.Publisher;
 import org.springframework.data.geo.Metrics;
 import org.springframework.data.geo.Point;
 import org.springframework.data.mongodb.ReactiveMongoDatabaseFactory;
-import org.springframework.data.mongodb.core.ReactiveMongoTemplate.NoOpDbRefResolver;
 import org.springframework.data.mongodb.core.ReactiveMongoTemplate.ReactiveSessionBoundMongoTemplate;
 import org.springframework.data.mongodb.core.aggregation.Aggregation;
 import org.springframework.data.mongodb.core.convert.MappingMongoConverter;
+import org.springframework.data.mongodb.core.convert.NoOpDbRefResolver;
 import org.springframework.data.mongodb.core.mapping.MongoMappingContext;
 import org.springframework.data.mongodb.core.query.NearQuery;
 import org.springframework.data.mongodb.core.query.Query;
@@ -64,6 +64,7 @@ import com.mongodb.reactivestreams.client.MongoDatabase;
  * Unit tests for {@link ReactiveSessionBoundMongoTemplate}.
  *
  * @author Christoph Strobl
+ * @author Mark Paluch
  */
 @SuppressWarnings("unchecked")
 @RunWith(MockitoJUnitRunner.Silent.class)
@@ -124,7 +125,7 @@ public class ReactiveSessionBoundMongoTemplateUnitTests {
 		factory = new SimpleReactiveMongoDatabaseFactory(client, "foo");
 
 		this.mappingContext = new MongoMappingContext();
-		this.converter = new MappingMongoConverter(new NoOpDbRefResolver(), mappingContext);
+		this.converter = new MappingMongoConverter(NoOpDbRefResolver.INSTANCE, mappingContext);
 		this.template = new ReactiveSessionBoundMongoTemplate(clientSession, new ReactiveMongoTemplate(factory, converter));
 	}