#521 - Add example for Kotlin Coroutines and Flow support.

Original pull request: #522.

Author: christophstrobl

mongodb/kotlin/README.md

@@ -63,3 +63,16 @@ Using the `Criteria` extensions allows to write type-safe queries via an ideomat
 operations.find<Person>(Query(Person::firstname isEqualTo "Tyrion"))
 ```
 
+## Coroutines and Flow support
+
+```kotlin
+runBlocking {
+	operations.find<Person>(Query(where("firstname").isEqualTo("Tyrion"))).awaitSingle()
+}
+```
+
+```kotlin
+runBlocking {
+	operations.findAll<Person>().asFlow().toList()
+}
+```

mongodb/kotlin/pom.xml

@@ -11,7 +11,15 @@
 	<artifactId>spring-data-mongodb-kotlin</artifactId>
 	<name>Spring Data MongoDB - Kotlin features</name>
 
+    <properties>
+        <kotlin-coroutines>1.3.0-RC2</kotlin-coroutines>
+    </properties>
+
 	<dependencies>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-data-mongodb-reactive</artifactId>
+		</dependency>
 		<dependency>
 			<groupId>org.jetbrains.kotlin</groupId>
 			<artifactId>kotlin-stdlib-jdk8</artifactId>
@@ -20,6 +28,21 @@
 			<groupId>org.jetbrains.kotlin</groupId>
 			<artifactId>kotlin-reflect</artifactId>
 		</dependency>
+        <dependency>
+            <groupId>org.jetbrains.kotlinx</groupId>
+            <artifactId>kotlinx-coroutines-core</artifactId>
+            <version>${kotlin-coroutines}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.jetbrains.kotlinx</groupId>
+            <artifactId>kotlinx-coroutines-reactor</artifactId>
+            <version>${kotlin-coroutines}</version>
+        </dependency>
+		<dependency>
+			<groupId>io.projectreactor</groupId>
+			<artifactId>reactor-test</artifactId>
+			<scope>test</scope>
+		</dependency>
 	</dependencies>
 
 	<build>

mongodb/kotlin/src/test/kotlin/example/springdata/mongodb/people/FlowAndCoroutinesTests.kt

@@ -0,0 +1,75 @@
+/*
+ * Copyright 2019 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 example.springdata.mongodb.people
+
+import kotlinx.coroutines.flow.toList
+import kotlinx.coroutines.reactive.awaitSingle
+import kotlinx.coroutines.reactive.flow.asFlow
+import kotlinx.coroutines.runBlocking
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.springframework.beans.factory.annotation.Autowired
+import org.springframework.boot.test.context.SpringBootTest
+import org.springframework.data.mongodb.core.*
+import org.springframework.data.mongodb.core.query.Criteria.where
+import org.springframework.data.mongodb.core.query.Query
+import org.springframework.data.mongodb.core.query.isEqualTo
+import org.springframework.test.context.junit4.SpringRunner
+import reactor.test.StepVerifier
+
+/**
+ *
+ * @author Christoph Strobl
+ */
+@RunWith(SpringRunner::class)
+@SpringBootTest
+class FlowAndCoroutinesTests {
+
+	@Autowired
+	lateinit var operations: ReactiveMongoOperations
+
+	@Before
+	fun before() {
+		StepVerifier.create(operations.dropCollection<Person>()).verifyComplete()
+	}
+
+	@Test
+	fun `find - the coroutine way`() {
+
+		StepVerifier.create(operations.insert<Person>().one(Person("Tyrion", "Lannister"))).expectNextCount(1).verifyComplete()
+
+		assertThat(
+				runBlocking {
+					operations.find<Person>(Query(where("firstname").isEqualTo("Tyrion"))).awaitSingle()
+				}
+		).extracting("firstname").isEqualTo("Tyrion")
+	}
+
+	@Test
+	fun `find - the flow way`() {
+
+		StepVerifier.create(operations.insert<Person>().one(Person("Tyrion", "Lannister"))).expectNextCount(1).verifyComplete()
+		StepVerifier.create(operations.insert<Person>().one(Person("Cersei", "Lannister"))).expectNextCount(1).verifyComplete()
+
+		assertThat(
+				runBlocking {
+					operations.findAll<Person>().asFlow().toList()
+				}
+		).extracting("firstname").containsExactlyInAnyOrder("Tyrion", "Cersei")
+	}
+}