DATAMONGO-1454 - Derive string query exists projection from return type.

String query methods can derive exists projection from a boolean return type.

Author: mp911de

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/Query.java

@@ -62,14 +62,6 @@
 	 */
 	boolean count() default false;
 
-	/**
-	 * Returns whether the query defined should be executed as exists projection.
-	 *
-	 * @since 1.10
-	 * @return
-	 */
-	boolean exists() default false;
-
 	/**
 	 * Returns whether the query should delete matching documents.
 	 * 

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/query/MongoQueryMethod.java

@@ -33,6 +33,7 @@
 import org.springframework.data.projection.ProjectionFactory;
 import org.springframework.data.repository.core.RepositoryMetadata;
 import org.springframework.data.repository.query.QueryMethod;
+import org.springframework.data.repository.util.QueryExecutionConverters;
 import org.springframework.data.util.ClassTypeInformation;
 import org.springframework.data.util.TypeInformation;
 import org.springframework.util.Assert;
@@ -53,6 +54,7 @@ public class MongoQueryMethod extends QueryMethod {
 
 	private final Method method;
 	private final MappingContext<? extends MongoPersistentEntity<?>, MongoPersistentProperty> mappingContext;
+	private final Class<?> unwrappedReturnType;
 
 	private MongoEntityMetadata<?> metadata;
 
@@ -73,6 +75,7 @@ public MongoQueryMethod(Method method, RepositoryMetadata metadata, ProjectionFa
 
 		this.method = method;
 		this.mappingContext = mappingContext;
+		this.unwrappedReturnType = potentiallyUnwrapReturnTypeFor(method);
 	}
 
 	/*
@@ -187,6 +190,16 @@ private boolean isGeoNearQuery(Method method) {
 		return false;
 	}
 
+	/**
+	 * Returns whether the query is a exists projection by checking the return type.
+	 *
+	 * @return
+	 * @since 1.10
+	 */
+	public boolean isExistsQuery() {
+		return unwrappedReturnType.isAssignableFrom(Boolean.class) || unwrappedReturnType.isAssignableFrom(Boolean.TYPE);
+	}
+
 	/**
 	 * Returns the {@link Query} annotation that is applied to the method or {@code null} if none available.
 	 * 
@@ -250,4 +263,14 @@ public org.springframework.data.mongodb.core.query.Meta getQueryMetaAttributes()
 
 		return metaAttributes;
 	}
+
+	private static Class<? extends Object> potentiallyUnwrapReturnTypeFor(Method method) {
+
+		if (QueryExecutionConverters.supports(method.getReturnType())) {
+			// unwrap only one level to handle cases like Future<List<Entity>> correctly.
+			return ClassTypeInformation.fromReturnTypeOf(method).getComponentType().getType();
+		}
+
+		return method.getReturnType();
+	}
 }

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/query/StringBasedMongoQuery.java

@@ -97,9 +97,9 @@ public StringBasedMongoQuery(String query, MongoQueryMethod method, MongoOperati
 		this.fieldSpec = BINDING_PARSER.parseAndCollectParameterBindingsFromQueryIntoBindings(
 				method.getFieldSpecification(), this.fieldSpecParameterBindings);
 
-		this.isCountQuery = method.hasAnnotatedQuery() ? method.getQueryAnnotation().count() : false;
-		this.isExistsQuery = method.hasAnnotatedQuery() ? method.getQueryAnnotation().exists() : false;
-		this.isDeleteQuery = method.hasAnnotatedQuery() ? method.getQueryAnnotation().delete() : false;
+		this.isCountQuery = method.hasAnnotatedQuery() && method.getQueryAnnotation().count();
+		this.isExistsQuery = method.isExistsQuery();
+		this.isDeleteQuery = method.hasAnnotatedQuery() && method.getQueryAnnotation().delete();
 
 		if (hasTwoQueryExecutions(this.isCountQuery, this.isExistsQuery, this.isDeleteQuery)) {
 			throw new IllegalArgumentException(String.format(COUNT_EXISTS_AND_DELETE, method));
@@ -165,7 +165,7 @@ private boolean hasTwoQueryExecutions(boolean isCountQuery, boolean isExistsQuer
 	 * 
 	 * @author Thomas Darimont
 	 */
-	private static enum ParameterBindingParser {
+	private enum ParameterBindingParser {
 
 		INSTANCE;
 
@@ -272,7 +272,7 @@ private static void collectParameterReferencesIntoBindings(List<ParameterBinding
 
 			} else if (value instanceof Pattern) {
 
-				String string = ((Pattern) value).toString().trim();
+				String string = value.toString().trim();
 				Matcher valueMatcher = PARSEABLE_BINDING_PATTERN.matcher(string);
 
 				while (valueMatcher.find()) {

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/PersonRepository.java

@@ -259,7 +259,7 @@ public interface PersonRepository extends MongoRepository<Person, String>, Query
 	/**
 	 * @see DATAMONGO-1454
 	 */
-	@Query(value = "{ 'lastname' : ?0 }", exists = true)
+	@Query(value = "{ 'lastname' : ?0 }")
 	boolean someExistQuery(String lastname);
 
 	/**

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/query/MongoQueryMethodUnitTests.java

@@ -21,6 +21,7 @@
 import java.lang.reflect.Method;
 import java.util.Collection;
 import java.util.List;
+import java.util.concurrent.Future;
 
 import org.junit.Before;
 import org.junit.Test;
@@ -212,6 +213,28 @@ public void fallsBackToRepositoryDomainTypeIfMethodDoesNotReturnADomainType() th
 		assertThat(method.getEntityInformation().getJavaType(), is(typeCompatibleWith(User.class)));
 	}
 
+	/**
+	 * @see DATAMONGO-1454
+	 */
+	@Test
+	public void createsMongoQueryMethodWithExistsProjection() throws Exception {
+
+		MongoQueryMethod method = queryMethod(PersonRepository.class, "existsBy");
+
+		assertThat(method.isExistsQuery(), is(true));
+	}
+
+	/**
+	 * @see DATAMONGO-1454
+	 */
+	@Test
+	public void createsMongoQueryMethodWithWrappedExistsProjection() throws Exception {
+
+		MongoQueryMethod method = queryMethod(PersonRepository.class, "existsByFuture");
+
+		assertThat(method.isExistsQuery(), is(true));
+	}
+
 	private MongoQueryMethod queryMethod(Class<?> repository, String name, Class<?>... parameters) throws Exception {
 
 		Method method = repository.getMethod(name, parameters);
@@ -254,6 +277,10 @@ interface PersonRepository extends Repository<User, Long> {
 		 * @see DATAMONGO-1266
 		 */
 		void deleteByUserName(String userName);
+
+		boolean existsBy();
+
+		Future<Boolean> existsByFuture();
 	}
 
 	interface SampleRepository extends Repository<Contact, Long> {

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/query/StringBasedMongoQueryUnitTests.java

@@ -61,6 +61,7 @@
  * @author Oliver Gierke
  * @author Christoph Strobl
  * @author Thomas Darimont
+ * @author Mark Paluch
  */
 @RunWith(MockitoJUnitRunner.class)
 public class StringBasedMongoQueryUnitTests {
@@ -148,7 +149,7 @@ public void bindsNullParametersCorrectly() throws Exception {
 	public void bindsDbrefCorrectly() throws Exception {
 
 		StringBasedMongoQuery mongoQuery = createQueryForMethod("findByHavingSizeFansNotZero");
-		ConvertingParameterAccessor accessor = StubParameterAccessor.getAccessor(converter, new Object[] {});
+		ConvertingParameterAccessor accessor = StubParameterAccessor.getAccessor(converter);
 
 		org.springframework.data.mongodb.core.query.Query query = mongoQuery.createQuery(accessor);
 		assertThat(query.getQueryObject(), is(new BasicQuery("{ fans : { $not : { $size : 0 } } }").getQueryObject()));
@@ -178,8 +179,7 @@ public void preventsDeleteAndCountFlagAtTheSameTime() throws Exception {
 	@Test
 	public void shouldSupportFindByParameterizedCriteriaAndFields() throws Exception {
 
-		ConvertingParameterAccessor accessor = StubParameterAccessor.getAccessor(converter, new Object[] {
-				new BasicDBObject("firstname", "first").append("lastname", "last"), Collections.singletonMap("lastname", 1) });
+		ConvertingParameterAccessor accessor = StubParameterAccessor.getAccessor(converter, new BasicDBObject("firstname", "first").append("lastname", "last"), Collections.singletonMap("lastname", 1));
 		StringBasedMongoQuery mongoQuery = createQueryForMethod("findByParameterizedCriteriaAndFields", DBObject.class,
 				Map.class);
 
@@ -196,7 +196,7 @@ public void shouldSupportFindByParameterizedCriteriaAndFields() throws Exception
 	@Test
 	public void shouldSupportRespectExistingQuotingInFindByTitleBeginsWithExplicitQuoting() throws Exception {
 
-		ConvertingParameterAccessor accessor = StubParameterAccessor.getAccessor(converter, new Object[] { "fun" });
+		ConvertingParameterAccessor accessor = StubParameterAccessor.getAccessor(converter, "fun");
 		StringBasedMongoQuery mongoQuery = createQueryForMethod("findByTitleBeginsWithExplicitQuoting", String.class);
 
 		org.springframework.data.mongodb.core.query.Query query = mongoQuery.createQuery(accessor);
@@ -210,7 +210,7 @@ public void shouldSupportRespectExistingQuotingInFindByTitleBeginsWithExplicitQu
 	@Test
 	public void shouldParseQueryWithParametersInExpression() throws Exception {
 
-		ConvertingParameterAccessor accessor = StubParameterAccessor.getAccessor(converter, new Object[] { 1, 2, 3, 4 });
+		ConvertingParameterAccessor accessor = StubParameterAccessor.getAccessor(converter, 1, 2, 3, 4);
 		StringBasedMongoQuery mongoQuery = createQueryForMethod("findByQueryWithParametersInExpression", int.class,
 				int.class, int.class, int.class);
 
@@ -362,6 +362,17 @@ public void shouldSupportNonQuotedBinaryDataReplacement() throws Exception {
 		assertThat(query.getQueryObject(), is(reference.getQueryObject()));
 	}
 
+	/**
+	 * @see DATAMONGO-1454
+	 */
+	@Test
+	public void shouldSupportExistsProjection() throws Exception {
+
+		StringBasedMongoQuery mongoQuery = createQueryForMethod("existsByLastname", String.class);
+
+		assertThat(mongoQuery.isExistsQuery(), is(true));
+	}
+
 	private StringBasedMongoQuery createQueryForMethod(String name, Class<?>... parameters) throws Exception {
 
 		Method method = SampleRepository.class.getMethod(name, parameters);
@@ -420,5 +431,8 @@ private interface SampleRepository extends Repository<Person, Long> {
 
 		@Query("{'id':?#{ [0] ? { $exists :true} : [1] }, 'foo':42, 'bar': ?#{ [0] ? { $exists :false} : [1] }}")
 		List<Person> findByQueryWithExpressionAndMultipleNestedObjects(boolean param0, String param1, String param2);
+
+		@Query(value = "{ 'lastname' : ?0 }")
+		boolean existsByLastname(String lastname);
 	}
 }