Add Kotlin example for Spring Data MongoDB.

mongodb/kotlin/src/main/kotlin/example/springdata/mongodb/people/ApplicationConfiguration.kt

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+/*
+ * 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 example.springdata.mongodb.people
+
+import org.springframework.boot.autoconfigure.SpringBootApplication
+import org.springframework.boot.runApplication
+
+/**
+ * @author Mark Paluch
+ */
+@SpringBootApplication
+class ApplicationConfiguration
+
+fun main(args: Array<String>) {
+	runApplication<ApplicationConfiguration>(*args)
+}

mongodb/kotlin/src/main/kotlin/example/springdata/mongodb/people/Person.kt

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+/*
+ * 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 example.springdata.mongodb.people
+
+import org.springframework.data.annotation.Id
+import org.springframework.data.annotation.PersistenceConstructor
+
+/**
+ * An entity to represent a Person.
+ *
+ * @author Mark Paluch
+ */
+data class Person @PersistenceConstructor constructor(@Id val id: String?, val firstname: String? = "Walter", val lastname: String = "") {
+	constructor(firstname: String?, lastname: String) : this(null, firstname, lastname);
+}

mongodb/kotlin/src/main/kotlin/example/springdata/mongodb/people/PersonRepository.kt

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+/*
+ * 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 example.springdata.mongodb.people
+
+import org.springframework.data.repository.CrudRepository
+
+/**
+ * Repository interface to manage [Person] instances.
+ *
+ * @author Mark Paluch
+ */
+interface PersonRepository : CrudRepository<Person, String> {
+
+	/**
+	 * Query method declaring a nullable return type that allows to return null values.
+	 */
+	fun findOneOrNoneByFirstname(firstname: String): Person?
+
+	/**
+	 * Query method declaring a nullable argument.
+	 */
+	fun findNullableByFirstname(firstname: String?): Person?
+
+	/**
+	 * Query method requiring a result. Throws [org.springframework.dao.EmptyResultDataAccessException] if no result is found.
+	 */
+	fun findOneByFirstname(firstname: String): Person
+}

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

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+/*
+ * 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 example.springdata.mongodb.people
+
+import org.assertj.core.api.Assertions.assertThat
+import org.assertj.core.api.Assertions.assertThatThrownBy
+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.dao.EmptyResultDataAccessException
+import org.springframework.test.context.junit4.SpringRunner
+
+/**
+ * Tests showing Kotlin usage of Spring Data Repositories.
+ *
+ * @author Mark Paluch
+ */
+@RunWith(SpringRunner::class)
+@SpringBootTest
+class RepositoryTests {
+
+	@Autowired
+	lateinit var repository: PersonRepository
+
+	@Before
+	fun before() {
+		repository.deleteAll()
+	}
+
+	@Test
+	fun `should find one person`() {
+
+		repository.save(Person("Walter", "White"))
+
+		val walter = repository.findOneByFirstname("Walter")
+
+		assertThat(walter).isNotNull()
+		assertThat(walter.firstname).isEqualTo("Walter")
+		assertThat(walter.lastname).isEqualTo("White")
+	}
+
+	@Test
+	fun `should return null if no person found`() {
+
+		repository.save(Person("Walter", "White"))
+
+		val walter = repository.findOneOrNoneByFirstname("Hank")
+
+		assertThat(walter).isNull()
+	}
+
+	@Test
+	fun `should throw EmptyResultDataAccessException if no person found`() {
+
+		repository.save(Person("Walter", "White"))
+
+		assertThatThrownBy { repository.findOneByFirstname("Hank") }.isInstanceOf(EmptyResultDataAccessException::class.java)
+	}
+
+	@Test
+	fun `should accept nullable parameters`() {
+
+		repository.save(Person(null, "Heisenberg"))
+
+		val heisenberg = repository.findNullableByFirstname(null)
+
+		assertThat(heisenberg).isNotNull()
+		assertThat(heisenberg!!.lastname).isEqualTo("Heisenberg")
+	}
+}

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

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+/*
+ * 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 example.springdata.mongodb.people
+
+import org.assertj.core.api.Assertions.assertThat
+import org.bson.Document
+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.query
+import org.springframework.data.mongodb.core.query.isEqualTo
+import org.springframework.test.context.junit4.SpringRunner
+
+/**
+ * Tests showing Kotlin usage of [MongoTemplate] and its Kotlin extensions.
+ *
+ * @author Mark Paluch
+ */
+@RunWith(SpringRunner::class)
+@SpringBootTest
+class TemplateTests {
+
+	@Autowired
+	lateinit var operations: MongoOperations
+
+	@Before
+	fun before() {
+		operations.dropCollection<Person>()
+	}
+
+	@Test
+	fun `should create collection leveraging reified type parameters`() {
+
+		operations.createCollection<Person>()
+
+		assertThat(operations.collectionNames).contains("person")
+	}
+
+	@Test
+	fun `should insert and find person in a fluent API style`() {
+
+		operations.insert<Person>().inCollection("person").one(Person("Walter", "White"))
+
+		val people = operations.query<Person>()
+				.matching(query(where("firstname").isEqualTo("Walter")))
+				.all()
+
+		assertThat(people).hasSize(1).extracting("firstname").containsOnly("Walter")
+	}
+
+	@Test
+	fun `should insert and project query results`() {
+
+		operations.insert<Person>().inCollection("person").one(Person("Walter", "White"))
+
+		val firstnameOnly = operations.query<Person>()
+				.asType<FirstnameOnly>()
+				.matching(query(where("firstname").isEqualTo("Walter")))
+				.oneValue()
+
+		assertThat(firstnameOnly?.getFirstname()).isEqualTo("Walter")
+	}
+
+	@Test
+	fun `should insert and count objects in a fluent API style`() {
+
+		operations.insert<Person>().inCollection("person").one(Person("Walter", "White"))
+
+		val count = operations.query<Person>()
+				.matching(query(where("firstname").isEqualTo("Walter")))
+				.count()
+
+		assertThat(count).isEqualTo(1)
+	}
+
+	@Test
+	fun `should insert and find person`() {
+
+		val person = Person("Walter", "White")
+
+		operations.insert(person)
+
+		val people = operations.find<Person>(query(where("firstname").isEqualTo("Walter")))
+
+		assertThat(people).hasSize(1).extracting("firstname").containsOnly("Walter")
+	}
+
+	@Test
+	fun `should apply defaulting for absent properties`() {
+
+		operations.insert<Document>().inCollection("person").one(Document("lastname", "White"))
+
+		val person = operations.query<Person>()
+				.matching(query(where("lastname").isEqualTo("White")))
+				.firstValue()!!
+
+		assertThat(person.firstname).isEqualTo("Walter")
+		assertThat(person.lastname).isEqualTo("White")
+
+
+		val walter = operations.findOne<Document>(query(where("lastname").isEqualTo("White")), "person")
+
+		assertThat(walter).isNotNull.containsEntry("lastname", "White").containsOnlyKeys("_id", "lastname")
+	}
+
+	interface FirstnameOnly {
+		fun getFirstname(): String
+	}
+}