Support Set return types in MongoDB AOT repositories.

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/aot/MongoCodeBlocks.java

@@ -15,6 +15,7 @@
  */
 package org.springframework.data.mongodb.repository.aot;
 
+import java.util.Set;
 import java.util.regex.Pattern;
 
 import org.bson.Document;
@@ -48,6 +49,7 @@
  * {@link CodeBlock} generator for common tasks.
  *
  * @author Christoph Strobl
+ * @author maryantocinn
  * @since 5.0
  */
 class MongoCodeBlocks {
@@ -237,8 +239,8 @@ static void appendReadPreference(AotQueryMethodGenerationContext context, Builde
 	}
 
 	/**
-	 * Wraps the given {@link CodeBlock} representing an {@link Iterable} into a {@link Streamable} if the
-	 * {@link MethodReturn} indicates so.
+	 * Adapts the given {@link CodeBlock} representing an {@link Iterable} to the declared collection return type if
+	 * necessary.
 	 */
 	public static CodeBlock potentiallyWrapStreamable(MethodReturn methodReturn, CodeBlock returningIterable) {
 
@@ -255,6 +257,11 @@ public static CodeBlock potentiallyWrapStreamable(MethodReturn methodReturn, Cod
 					returnType, DefaultConversionService.class, Streamable.class, returningIterable, TypeDescriptor.class);
 		}
 
+		if (ClassUtils.isAssignable(Set.class, returnType)) {
+			return CodeBlock.of("$2T.getSharedInstance().convert($3L, $1T.class)", returnType,
+					DefaultConversionService.class, returningIterable);
+		}
+
 		return returningIterable;
 	}
 

spring-data-mongodb/src/test/java/example/aot/UserRepository.java

@@ -52,13 +52,16 @@
 
 /**
  * @author Christoph Strobl
+ * @author maryantocinn
  */
 public interface UserRepository extends CrudRepository<User, String> {
 
 	/* Derived Queries */
 
 	List<User> findUserNoArgumentsBy();
 
+	Set<User> findUserSetBy();
+
 	Streamable<User> streamUserNoArgumentsBy();
 
 	User findOneByUsername(String username);
@@ -234,6 +237,8 @@ public interface UserRepository extends CrudRepository<User, String> {
 
 	List<UserProjection> findUserProjectionByLastnameStartingWith(String lastname);
 
+	Set<UserProjection> findUserProjectionSetByLastnameStartingWith(String lastname);
+
 	Page<UserProjection> findUserProjectionByLastnameStartingWith(String lastname, Pageable page);
 
 	<T> Page<T> findUserProjectionByLastnameStartingWith(String lastname, Pageable page, Class<T> projectionType);

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/aot/MongoRepositoryContributorTests.java

@@ -26,6 +26,7 @@
 import java.time.Instant;
 import java.util.List;
 import java.util.Optional;
+import java.util.Set;
 import java.util.regex.Pattern;
 
 import org.bson.BsonString;
@@ -79,6 +80,7 @@
  *
  * @author Christoph Strobl
  * @author Mark Paluch
+ * @author maryantocinn
  */
 @Testcontainers(disabledWithoutDocker = true)
 @SpringJUnitConfig(classes = MongoRepositoryContributorTests.MongoRepositoryContributorConfiguration.class)
@@ -200,6 +202,15 @@ void testDerivedFinderWithoutArguments() {
 		assertThat(users).hasSize(7).hasOnlyElementsOfType(User.class);
 	}
 
+	@Test // GH-5225
+	void testDerivedQueryAsSet() {
+
+		Set<User> users = fragment.findUserSetBy();
+
+		assertThat(users).isInstanceOf(Set.class).extracting(User::getUsername).containsExactlyInAnyOrder("luke", "leia",
+				"han", "chewbacca", "yoda", "vader", "kylo");
+	}
+
 	@Test
 	void testCountWorksAsExpected() {
 
@@ -563,6 +574,14 @@ void testDerivedFinderReturningListOfProjections() {
 		assertThat(users).extracting(UserProjection::getUsername).containsExactlyInAnyOrder("han", "kylo", "luke", "vader");
 	}
 
+	@Test // GH-5225
+	void testDerivedQueryReturningSetOfProjections() {
+
+		Set<UserProjection> users = fragment.findUserProjectionSetByLastnameStartingWith("S");
+		assertThat(users).isInstanceOf(Set.class).extracting(UserProjection::getUsername)
+				.containsExactlyInAnyOrder("han", "kylo", "luke", "vader");
+	}
+
 	@Test
 	void testDerivedFinderReturningPageOfProjections() {
 

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/aot/QueryMethodContributionUnitTests.java

@@ -64,6 +64,7 @@
  * @author Christoph Strobl
  * @author Mark Paluch
  * @author Tomasz Forys
+ * @author maryantocinn
  */
 class QueryMethodContributionUnitTests {
 
@@ -399,6 +400,17 @@ void rendersStreamableReturnType() throws NoSuchMethodException {
 				.containsSubsequence("return", "Streamable.of(", "all())");
 	}
 
+	@Test // GH-5225
+	void rendersSetReturnType() throws NoSuchMethodException {
+
+		MethodSpec methodSpec = codeOf(UserRepository.class, "findUserSetBy");
+
+		assertThat(methodSpec.toString()) //
+				.contains("DefaultConversionService.getSharedInstance().convert(") //
+				.containsSubsequence("return", "all()", "Set.class") //
+				.doesNotContain("return finder.matching(filterQuery).all()");
+	}
+
 	@Test // GH-5089
 	void rendersStreamableReturnTypeForAggregation() throws NoSuchMethodException {