Show how to use Limit with repository queries.

Add methods taking a Limit parameter to various samples.

Original pull request: #672
Closes #671

Author: christophstrobl

cassandra/example/src/main/java/example/springdata/cassandra/basic/BasicUserRepository.java

@@ -18,6 +18,7 @@
 import java.util.List;
 
 import org.springframework.data.cassandra.repository.Query;
+import org.springframework.data.domain.Limit;
 import org.springframework.data.repository.CrudRepository;
 
 /**
@@ -55,4 +56,13 @@ public interface BasicUserRepository extends CrudRepository<User, Long> {
 	 * @return
 	 */
 	List<User> findUsersByLastnameStartsWith(String lastnamePrefix);
+
+	/**
+	 * Same as {@link #findUsersByLastnameStartsWith(String)} but reducing the result size to a given {@link Limit}.
+	 *
+	 * @param lastnamePrefix
+	 * @param maxResults the maximum number of results returned.
+	 * @return
+	 */
+	List<User> findUsersByLastnameStartsWith(String lastnamePrefix, Limit maxResults);
 }

cassandra/example/src/main/java/example/springdata/cassandra/basic/User.java

@@ -43,4 +43,10 @@ public class User {
 	public User(Long id) {
 		this.setId(id);
 	}
+
+	public User(Long id, String firstname, String lastname) {
+		this.id = id;
+		this.firstname = firstname;
+		this.lastname = lastname;
+	}
 }

cassandra/example/src/test/java/example/springdata/cassandra/basic/BasicUserRepositoryTests.java

@@ -18,6 +18,8 @@
 import static org.assertj.core.api.Assertions.*;
 import static org.assertj.core.api.Assumptions.*;
 
+import java.util.stream.LongStream;
+
 import example.springdata.cassandra.util.CassandraKeyspace;
 import example.springdata.cassandra.util.CassandraVersion;
 
@@ -26,6 +28,7 @@
 
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.data.domain.Limit;
 import org.springframework.data.util.Version;
 
 import com.datastax.oss.driver.api.core.CqlSession;
@@ -120,4 +123,24 @@ void findByDerivedQueryMethodWithSASI() throws InterruptedException {
 
 		assertThat(repository.findUsersByLastnameStartsWith("last")).contains(user);
 	}
+
+	/**
+	 * Spring Data Cassandra supports {@code Limit} to reduce the number of returned results.
+	 */
+	@Test
+	void limitResultSize() throws InterruptedException {
+
+		assumeThat(CassandraVersion.getReleaseVersion(session).isGreaterThanOrEqualTo(CASSANDRA_3_4)).isTrue();
+
+		session.execute("CREATE CUSTOM INDEX ON users (lname) USING 'org.apache.cassandra.index.sasi.SASIIndex';");
+		/*
+		  Cassandra secondary indexes are created in the background without the possibility to check
+		  whether they are available or not. So we are forced to just wait. *sigh*
+		 */
+		Thread.sleep(1000);
+
+		LongStream.range(0, 10).forEach(id -> repository.save(new User(id, user.getFirstname(), user.getLastname())));
+
+		assertThat(repository.findUsersByLastnameStartsWith("last", Limit.of(5))).hasSize(5);
+	}
 }

cassandra/reactive/src/main/java/example/springdata/cassandra/people/ReactivePersonRepository.java

@@ -15,6 +15,7 @@
  */
 package example.springdata.cassandra.people;
 
+import org.springframework.data.domain.Limit;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
@@ -36,6 +37,15 @@ public interface ReactivePersonRepository extends ReactiveCrudRepository<Person,
 	 */
 	Flux<Person> findByLastname(String lastname);
 
+	/**
+	 * Derived query selecting by {@code lastname} reducing the result size to a given {@link Limit}.
+	 *
+	 * @param lastname
+	 * @param maxResults the maximum number of results returned.
+	 * @return
+	 */
+	Flux<Person> findByLastname(String lastname, Limit maxResults);
+
 	/**
 	 * String query selecting one entity.
 	 *

cassandra/reactive/src/test/java/example/springdata/cassandra/people/ReactivePersonRepositoryIntegrationTest.java

@@ -16,6 +16,7 @@
 package example.springdata.cassandra.people;
 
 import example.springdata.cassandra.util.CassandraKeyspace;
+import org.springframework.data.domain.Limit;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 import reactor.test.StepVerifier;
@@ -89,6 +90,14 @@ void shouldQueryDataWithQueryDerivation() {
 		StepVerifier.create(repository.findByLastname("White")).expectNextCount(2).verifyComplete();
 	}
 
+	/**
+	 * Fetch data limiting result size.
+	 */
+	@Test
+	void limitResultSize() {
+		StepVerifier.create(repository.findByLastname("White", Limit.of(1))).expectNextCount(1).verifyComplete();
+	}
+
 	/**
 	 * Fetch data using a string query.
 	 */

jpa/example/src/main/java/example/springdata/jpa/simple/SimpleUserRepository.java

@@ -20,6 +20,7 @@
 import java.util.concurrent.CompletableFuture;
 import java.util.stream.Stream;
 
+import org.springframework.data.domain.Limit;
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.domain.Slice;
 import org.springframework.data.domain.Sort;
@@ -63,6 +64,17 @@ public interface SimpleUserRepository extends ListCrudRepository<User, Long> {
 	 */
 	List<User> findByLastname(String lastname);
 
+	/**
+	 * Find at most the number of users defined via maxResults with the given lastname.
+	 * This method will be translated into a query by constructing it directly from the method name as there is no other
+	 * query declared.
+	 *
+	 * @param lastname
+	 * @param maxResults the maximum number of results returned.
+	 * @return
+	 */
+	List<User> findByLastname(String lastname, Limit maxResults);
+
 	/**
 	 * Returns all users with the given firstname. This method will be translated into a query using the one declared in
 	 * the {@link Query} annotation declared one.
@@ -73,6 +85,17 @@ public interface SimpleUserRepository extends ListCrudRepository<User, Long> {
 	@Query("select u from User u where u.firstname = :firstname")
 	List<User> findByFirstname(String firstname);
 
+	/**
+	 * Returns at most the number of users defined via {@link Limit} with the given firstname. This method will be
+	 * translated into a query using the one declared in the {@link Query} annotation declared one.
+	 *
+	 * @param firstname
+	 * @param maxResults the maximum number of results returned.
+	 * @return
+	 */
+	@Query("select u from User u where u.firstname = :firstname")
+	List<User> findByFirstname(String firstname, Limit maxResults);
+
 	/**
 	 * Returns all users with the given name as first- or lastname. This makes the query to method relation much more
 	 * refactoring-safe as the order of the method parameters is completely irrelevant.

jpa/example/src/test/java/example/springdata/jpa/simple/SimpleUserRepositoryTests.java

@@ -27,6 +27,7 @@
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.TimeUnit;
 import java.util.stream.Collectors;
+import java.util.stream.IntStream;
 import java.util.stream.Stream;
 
 import org.junit.jupiter.api.Assertions;
@@ -36,6 +37,7 @@
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.dao.InvalidDataAccessApiUsageException;
+import org.springframework.data.domain.Limit;
 import org.springframework.data.domain.PageRequest;
 import org.springframework.data.domain.Sort;
 import org.springframework.transaction.annotation.Propagation;
@@ -83,6 +85,22 @@ void findSavedUserByLastname() {
 		assertThat(repository.findByLastname("lastname")).contains(user);
 	}
 
+	@Test
+	void findLimitedNumberOfUsersViaDerivedQuery() {
+
+		IntStream.range(0, 10).forEach($ -> repository.save(new User(user.getFirstname(), user.getLastname())));
+
+		assertThat(repository.findByLastname("lastname", Limit.of(5))).hasSize(5);
+	}
+
+	@Test
+	void findLimitedNumberOfUsersViaAnnotatedQuery() {
+
+		IntStream.range(0, 10).forEach($ -> repository.save(new User(user.getFirstname(), user.getLastname())));
+
+		assertThat(repository.findByFirstname(user.getFirstname(), Limit.of(5))).hasSize(5);
+	}
+
 	@Test
 	void findByFirstnameOrLastname() {
 

mongodb/example/src/main/java/example/springdata/mongodb/customer/CustomerRepository.java

@@ -18,6 +18,7 @@
 import java.util.List;
 import java.util.stream.Stream;
 
+import org.springframework.data.domain.Limit;
 import org.springframework.data.domain.Sort;
 import org.springframework.data.geo.Distance;
 import org.springframework.data.geo.GeoResults;
@@ -41,6 +42,15 @@ public interface CustomerRepository extends CrudRepository<Customer, String> {
 	 */
 	List<Customer> findByLastname(String lastname, Sort sort);
 
+	/**
+	 * Derived query reducing result size to a given {@link Limit}.
+	 *
+	 * @param lastname
+	 * @param maxResults the maximum number of results returned.
+	 * @return
+	 */
+	List<Customer> findByLastname(String lastname, Limit maxResults);
+
 	/**
 	 * Showcase for a repository query using geospatial functionality.
 	 *

mongodb/example/src/test/java/example/springdata/mongodb/customer/CustomerRepositoryIntegrationTest.java

@@ -27,6 +27,7 @@
 
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.autoconfigure.data.mongo.DataMongoTest;
+import org.springframework.data.domain.Limit;
 import org.springframework.data.geo.Distance;
 import org.springframework.data.geo.Metrics;
 import org.springframework.data.geo.Point;
@@ -96,6 +97,17 @@ void findCustomersUsingQuerydslSort() {
 		assertThat(result.get(1)).isEqualTo(oliver);
 	}
 
+	/**
+	 * Test case to show how to reduce result size with dynamic {@link Limit}.
+	 */
+	@Test
+	void limitResultSize() {
+
+		var result = repository.findByLastname("Matthews", Limit.of(1));
+
+		assertThat(result).hasSize(1);
+	}
+
 	/**
 	 * Test case to show the usage of Java {@link Stream}.
 	 */

mongodb/reactive/src/main/java/example/springdata/mongodb/people/ReactivePersonRepository.java

@@ -15,6 +15,9 @@
  */
 package example.springdata.mongodb.people;
 
+import java.util.List;
+
+import org.springframework.data.domain.Limit;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
@@ -37,6 +40,17 @@ public interface ReactivePersonRepository extends ReactiveCrudRepository<Person,
 	 */
 	Flux<Person> findByLastname(String lastname);
 
+	/**
+	 * Find at most the number of users defined via maxResults with the given lastname.
+	 * This method will be translated into a query by constructing it directly from the method name as there is no other
+	 * query declared.
+	 *
+	 * @param lastname
+	 * @param maxResults the maximum number of results returned.
+	 * @return
+	 */
+	Flux<Person> findByLastname(String lastname, Limit maxResults);
+
 	/**
 	 * String query selecting one entity.
 	 *

mongodb/reactive/src/test/java/example/springdata/mongodb/people/ReactivePersonRepositoryIntegrationTest.java

@@ -18,6 +18,7 @@
 import static org.assertj.core.api.Assertions.*;
 
 import example.springdata.mongodb.util.MongoContainers;
+import org.springframework.data.domain.Limit;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 import reactor.test.StepVerifier;
@@ -157,6 +158,14 @@ void shouldQueryDataWithQueryDerivation() {
 		repository.findByLastname("White").as(StepVerifier::create).expectNextCount(2).verifyComplete();
 	}
 
+	/**
+	 * Limit result size.
+	 */
+	@Test
+	void shouldLimitResultSize() {
+		repository.findByLastname("White", Limit.of(1)).as(StepVerifier::create).expectNextCount(1).verifyComplete();
+	}
+
 	/**
 	 * Fetch data using a string query.
 	 */

r2dbc/example/src/main/java/example/springdata/r2dbc/basics/CustomerRepository.java

@@ -15,6 +15,7 @@
  */
 package example.springdata.r2dbc.basics;
 
+import org.springframework.data.domain.Limit;
 import reactor.core.publisher.Flux;
 
 import org.springframework.data.r2dbc.repository.Query;
@@ -28,4 +29,6 @@ interface CustomerRepository extends ReactiveCrudRepository<Customer, Long> {
 
 	@Query("select id, firstname, lastname from customer c where c.lastname = :lastname")
 	Flux<Customer> findByLastname(String lastname);
+
+	Flux<Customer> findByLastname(String lastname, Limit limit);
 }

r2dbc/example/src/test/java/example/springdata/r2dbc/basics/TransactionalServiceIntegrationTests.java

@@ -15,6 +15,7 @@
  */
 package example.springdata.r2dbc.basics;
 
+import org.springframework.data.domain.Limit;
 import reactor.core.publisher.Hooks;
 import reactor.test.StepVerifier;
 
@@ -72,6 +73,25 @@ void exceptionTriggersRollback() {
 				.verifyComplete();
 	}
 
+	@Test
+	void limitResultSize() {
+
+		service.save(new Customer(null, "Carter", "Matthews")) //
+				.as(StepVerifier::create) //
+				.expectNextMatches(Customer::hasId) //
+				.verifyComplete();
+
+		service.save(new Customer(null, "Evad", "Matthews")) //
+				.as(StepVerifier::create) //
+				.expectNextMatches(Customer::hasId) //
+				.verifyComplete();
+
+		repository.findByLastname("Matthews", Limit.of(1)) //
+				.as(StepVerifier::create) //
+				.expectNextCount(1)
+				.verifyComplete();
+	}
+
 	@Test // #500
 	void insertsDataTransactionally() {