DATACASS-771 - Fix return type detection for suspended Kotlin methods.

See DATACMNS-1738 for further reference.

spring-data-cassandra/src/main/java/org/springframework/data/cassandra/repository/query/ReactiveCassandraQueryMethod.java

@@ -25,6 +25,7 @@ import org.springframework.data.projection.ProjectionFactory;
 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.Lazy;
 
 /**
  * Reactive specific implementation of {@link CassandraQueryMethod}.
@@ -34,7 +35,7 @@ import org.springframework.data.repository.util.ReactiveWrappers;
  */
 public class ReactiveCassandraQueryMethod extends CassandraQueryMethod {
 
-	private final Method method;
+	private final Lazy<Boolean> isCollectionQuery;
 
 	/**
 	 * Create a new {@link ReactiveCassandraQueryMethod} from the given {@link Method}.
@@ -49,7 +50,8 @@ public class ReactiveCassandraQueryMethod extends CassandraQueryMethod {
 
 		super(method, metadata, projectionFactory, mappingContext);
 
-		this.method = method;
+		this.isCollectionQuery = Lazy.of(() -> !(isPageQuery() || isSliceQuery())
+				&& ReactiveWrappers.isMultiValueType(metadata.getReturnType(method).getType()));
 	}
 
 	/*
@@ -58,7 +60,7 @@ public class ReactiveCassandraQueryMethod extends CassandraQueryMethod {
 	 */
 	@Override
 	public boolean isCollectionQuery() {
-		return !(isPageQuery() || isSliceQuery()) && ReactiveWrappers.isMultiValueType(method.getReturnType());
+		return isCollectionQuery.get();
 	}
 
 	/*

spring-data-cassandra/src/test/kotlin/org/springframework/data/cassandra/repository/query/ReactiveCassandraQueryMethodCoroutineUnitTests.kt

@@ -0,0 +1,62 @@
+/*
+ * 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.cassandra.repository.query
+
+import kotlinx.coroutines.flow.Flow
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.Test
+import org.springframework.data.cassandra.core.mapping.CassandraMappingContext
+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 [ReactiveCassandraQueryMethod] using Coroutine repositories.
+ *
+ * @author Mark Paluch
+ */
+class ReactiveCassandraQueryMethodCoroutineUnitTests {
+
+	val projectionFactory = SpelAwareProxyProjectionFactory()
+
+	data class Person(val id: String)
+
+	interface PersonRepository : CoroutineCrudRepository<Person, String> {
+
+		suspend fun findSuspendAllByName(): Flow<Person>
+
+		fun findAllByName(): Flow<Person>
+	}
+
+	@Test // DATACASS-771
+	internal fun `should consider methods returning Flow as collection queries`() {
+
+		val method = PersonRepository::class.java.getMethod("findAllByName")
+		val queryMethod = ReactiveCassandraQueryMethod(method, DefaultRepositoryMetadata(PersonRepository::class.java), projectionFactory, CassandraMappingContext())
+
+		assertThat(queryMethod.isCollectionQuery).isTrue()
+	}
+
+	@Test // DATACASS-771
+	internal fun `should consider suspended methods returning Flow as collection queries`() {
+
+		val method = PersonRepository::class.java.getMethod("findSuspendAllByName", Continuation::class.java)
+		val queryMethod = ReactiveCassandraQueryMethod(method, DefaultRepositoryMetadata(PersonRepository::class.java), projectionFactory, CassandraMappingContext())
+
+		assertThat(queryMethod.isCollectionQuery).isTrue()
+	}
+}