DATAMONGO-2562 - Fix return type detection for suspended Kotlin methods.

See DATACMNS-1738 for further reference.

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

@@ -34,6 +34,7 @@ import org.springframework.data.repository.core.RepositoryMetadata;
 import org.springframework.data.repository.util.ReactiveWrapperConverters;
 import org.springframework.data.repository.util.ReactiveWrappers;
 import org.springframework.data.util.ClassTypeInformation;
+import org.springframework.data.util.Lazy;
 import org.springframework.data.util.TypeInformation;
 import org.springframework.util.ClassUtils;
 
@@ -50,6 +51,7 @@ public class ReactiveMongoQueryMethod extends MongoQueryMethod {
 	private static final ClassTypeInformation<Slice> SLICE_TYPE = ClassTypeInformation.from(Slice.class);
 
 	private final Method method;
+	private final Lazy<Boolean> isCollectionQuery;
 
 	/**
 	 * Creates a new {@link ReactiveMongoQueryMethod} from the given {@link Method}.
@@ -92,6 +94,8 @@ public class ReactiveMongoQueryMethod extends MongoQueryMethod {
 		}
 
 		this.method = method;
+		this.isCollectionQuery = Lazy.of(() -> !(isPageQuery() || isSliceQuery())
+				&& ReactiveWrappers.isMultiValueType(metadata.getReturnType(method).getType()));
 	}
 
 	/*
@@ -109,7 +113,7 @@ public class ReactiveMongoQueryMethod extends MongoQueryMethod {
 	 */
 	@Override
 	public boolean isCollectionQuery() {
-		return !(isPageQuery() || isSliceQuery()) && ReactiveWrappers.isMultiValueType(method.getReturnType());
+		return isCollectionQuery.get();
 	}
 
 	/*

spring-data-mongodb/src/test/kotlin/org/springframework/data/mongodb/repository/query/ReactiveMongoQueryMethodCoroutineUnitTests.kt

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2020 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
+ *
+ *      https://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.repository.query
+
+import kotlinx.coroutines.flow.Flow
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.Test
+import org.springframework.data.mongodb.core.mapping.MongoMappingContext
+import org.springframework.data.mongodb.repository.Person
+import org.springframework.data.projection.SpelAwareProxyProjectionFactory
+import org.springframework.data.repository.core.support.DefaultRepositoryMetadata
+import org.springframework.data.repository.kotlin.CoroutineCrudRepository
+import kotlin.coroutines.Continuation
+
+/**
+ * Unit tests for [ReactiveMongoQueryMethod] using Coroutine repositories.
+ *
+ * @author Mark Paluch
+ */
+class ReactiveMongoQueryMethodCoroutineUnitTests {
+
+	val projectionFactory = SpelAwareProxyProjectionFactory()
+
+	interface PersonRepository : CoroutineCrudRepository<Person, String> {
+
+		suspend fun findSuspendAllByName(): Flow<Person>
+
+		fun findAllByName(): Flow<Person>
+	}
+
+	@Test // DATAMONGO-2562
+	internal fun `should consider methods returning Flow as collection queries`() {
+
+		val method = PersonRepository::class.java.getMethod("findAllByName")
+		val queryMethod = ReactiveMongoQueryMethod(method, DefaultRepositoryMetadata(PersonRepository::class.java), projectionFactory, MongoMappingContext())
+
+		assertThat(queryMethod.isCollectionQuery).isTrue()
+	}
+
+	@Test // DATAMONGO-2562
+	internal fun `should consider suspended methods returning Flow as collection queries`() {
+
+		val method = PersonRepository::class.java.getMethod("findSuspendAllByName", Continuation::class.java)
+		val queryMethod = ReactiveMongoQueryMethod(method, DefaultRepositoryMetadata(PersonRepository::class.java), projectionFactory, MongoMappingContext())
+
+		assertThat(queryMethod.isCollectionQuery).isTrue()
+	}
+}