feat: support stream in spring data repository

docs/en/jpql-with-kotlin-jdsl/spring-supports.md

@@ -12,23 +12,33 @@ If you declare your `JpqlSerializer` or `JpqlIntrospector` as a bean, it will be
 If your `JpaRepository` extends `KotlinJdslJpqlExecutor`, you can use the extension provided by Kotlin JDSL.
 
 ```kotlin
-interface AuthorRepository : JpaRepository<Author, Long>, KotlinJdslJpqlExecutor
 interface BookRepository : JpaRepository<Book, Isbn>, KotlinJdslJpqlExecutor
 
-authorRepository.findAll {
+val result: List<Isbn?> = bookRepository.findAll {
     select(
-        path(Author::authorId),
+        path(Book::isbn),
+    ).from(
+        entity(Book::class),
+    )
+}
+
+val result: Page<Isbn?> = bookRepository.findPage(pageable) {
+    select(
+        path(Book::isbn),
     ).from(
-        entity(Author::class),
-        join(BookAuthor::class).on(path(Author::authorId).equal(path(BookAuthor::authorId))),
-    ).groupBy(
-        path(Author::authorId),
-    ).orderBy(
-        count(Author::authorId).desc(),
+        entity(Book::class),
+    )
+}
+
+val result: Slice<Isbn?> = bookRepository.findSlice(pageable) {
+    select(
+        path(Book::isbn),
+    ).from(
+        entity(Book::class),
     )
 }
 
-bookRepository.findPage(pageable) {
+val result: Stream<Isbn?> = bookRepository.findStream {
     select(
         path(Book::isbn),
     ).from(

docs/ko/jpql-with-kotlin-jdsl/spring-supports.md

@@ -12,23 +12,33 @@ Kotlin JDSL은 Spring Boot AutoConfigure를 지원합니다.
 만약 사용하고 있는 `JpaRepository`가 `KotlinJdslJpqlExecutor`를 상속하면, Kotlin JDSL이 제공하는 확장 기능을 사용할 수 있습니다.
 
 ```kotlin
-interface AuthorRepository : JpaRepository<Author, Long>, KotlinJdslJpqlExecutor
 interface BookRepository : JpaRepository<Book, Isbn>, KotlinJdslJpqlExecutor
 
-authorRepository.findAll {
+val result: List<Isbn?> = bookRepository.findAll {
     select(
-        path(Author::authorId),
+        path(Book::isbn),
+    ).from(
+        entity(Book::class),
+    )
+}
+
+val result: Page<Isbn?> = bookRepository.findPage(pageable) {
+    select(
+        path(Book::isbn),
     ).from(
-        entity(Author::class),
-        join(BookAuthor::class).on(path(Author::authorId).equal(path(BookAuthor::authorId))),
-    ).groupBy(
-        path(Author::authorId),
-    ).orderBy(
-        count(Author::authorId).desc(),
+        entity(Book::class),
+    )
+}
+
+val result: Slice<Isbn?> = bookRepository.findSlice(pageable) {
+    select(
+        path(Book::isbn),
+    ).from(
+        entity(Book::class),
     )
 }
 
-bookRepository.findPage(pageable) {
+val result: Stream<Isbn?> = bookRepository.findStream {
     select(
         path(Book::isbn),
     ).from(

example/spring-data-jpa-javax/src/test/kotlin/com/linecorp/kotlinjdsl/example/spring/data/jpa/javax/jpql/select/SelectExample.kt

@@ -18,6 +18,7 @@ import org.springframework.data.domain.PageRequest
 import org.springframework.data.domain.Sort
 import org.springframework.transaction.annotation.Transactional
 import java.time.OffsetDateTime
+import java.util.stream.Collectors
 
 @Transactional
 @SpringBootTest
@@ -89,6 +90,30 @@ class SelectExample : WithAssertions {
         assertThat(actual).isEqualTo(listOf(Isbn("04"), Isbn("05"), Isbn("06")))
     }
 
+    @Test
+    fun `the stream of books`() {
+        // given
+        val pageable = PageRequest.of(1, 3, Sort.by(Sort.Direction.ASC, "isbn"))
+
+        // when
+        val actual = bookRepository.findStream(pageable) {
+            select(
+                path(Book::isbn),
+            ).from(
+                entity(Book::class),
+            )
+        }
+
+        // then
+        assertThat(actual.collect(Collectors.toList())).isEqualTo(
+            listOf(
+                Isbn("04"),
+                Isbn("05"),
+                Isbn("06"),
+            ),
+        )
+    }
+
     @Test
     fun `the page of books`() {
         // given
@@ -302,6 +327,39 @@ class SelectExample : WithAssertions {
         )
     }
 
+    @Test
+    fun the_number_of_employees_per_department_stream() {
+        // given
+        data class Row(
+            val departmentId: Long,
+            val count: Long,
+        )
+
+        // when
+        val actual = employeeRepository.findStream {
+            selectNew<Row>(
+                path(EmployeeDepartment::departmentId),
+                count(Employee::employeeId),
+            ).from(
+                entity(Employee::class),
+                join(Employee::departments),
+            ).groupBy(
+                path(EmployeeDepartment::departmentId),
+            ).orderBy(
+                path(EmployeeDepartment::departmentId).asc(),
+            )
+        }
+
+        // then
+        assertThat(actual.collect(Collectors.toList())).isEqualTo(
+            listOf(
+                Row(1, 6),
+                Row(2, 15),
+                Row(3, 18),
+            ),
+        )
+    }
+
     @Test
     fun `the number of employees who belong to more than one department`() {
         // when

example/spring-data-jpa/src/test/kotlin/com/linecorp/kotlinjdsl/example/spring/data/jpa/jpql/select/SelectExample.kt

@@ -147,6 +147,24 @@ class SelectExample : WithAssertions {
         assertThat(actual.hasNext()).isTrue
     }
 
+    @Test
+    fun `the stream of books`() {
+        // given
+        val pageable = PageRequest.of(1, 3, Sort.by(Sort.Direction.ASC, "isbn"))
+
+        // when
+        val actual = bookRepository.findStream(pageable) {
+            select(
+                path(Book::isbn),
+            ).from(
+                entity(Book::class),
+            )
+        }
+
+        // then
+        assertThat(actual.toList()).isEqualTo(listOf(Isbn("04"), Isbn("05"), Isbn("06")))
+    }
+
     @Test
     fun `the book with the most authors`() {
         // when
@@ -321,6 +339,39 @@ class SelectExample : WithAssertions {
         )
     }
 
+    @Test
+    fun the_number_of_employees_per_department_stream() {
+        // given
+        data class Row(
+            val departmentId: Long,
+            val count: Long,
+        )
+
+        // when
+        val actual = employeeRepository.findStream {
+            selectNew<Row>(
+                path(EmployeeDepartment::departmentId),
+                count(Employee::employeeId),
+            ).from(
+                entity(Employee::class),
+                join(Employee::departments),
+            ).groupBy(
+                path(EmployeeDepartment::departmentId),
+            ).orderBy(
+                path(EmployeeDepartment::departmentId).asc(),
+            )
+        }
+
+        // then
+        assertThat(actual.toList()).isEqualTo(
+            listOf(
+                Row(1, 6),
+                Row(2, 15),
+                Row(3, 18),
+            ),
+        )
+    }
+
     @Test
     fun `the number of employees who belong to more than one department`() {
         // given

support/spring-data-jpa-javax/src/main/kotlin/com/linecorp/kotlinjdsl/support/spring/data/jpa/javax/repository/KotlinJdslJpqlExecutor.kt

@@ -11,6 +11,7 @@ import org.springframework.data.domain.Page
 import org.springframework.data.domain.Pageable
 import org.springframework.data.domain.Slice
 import org.springframework.data.repository.NoRepositoryBean
+import java.util.stream.Stream
 
 @NoRepositoryBean
 @SinceJdsl("3.0.0")
@@ -134,6 +135,67 @@ interface KotlinJdslJpqlExecutor {
         init: DSL.() -> JpqlQueryable<SelectQuery<T>>,
     ): Slice<T?>
 
+    /**
+     * Returns all results of the select query.
+     */
+    @SinceJdsl("3.5.4")
+    fun <T : Any> findStream(
+        offset: Int? = null,
+        limit: Int? = null,
+        init: Jpql.() -> JpqlQueryable<SelectQuery<T>>,
+    ): Stream<T?>
+
+    /**
+     * Returns all results of the select query.
+     */
+    @SinceJdsl("3.5.4")
+    fun <T : Any, DSL : JpqlDsl> findStream(
+        dsl: JpqlDsl.Constructor<DSL>,
+        offset: Int? = null,
+        limit: Int? = null,
+        init: DSL.() -> JpqlQueryable<SelectQuery<T>>,
+    ): Stream<T?>
+
+    /**
+     * Returns all results of the select query.
+     */
+    @SinceJdsl("3.5.4")
+    fun <T : Any, DSL : JpqlDsl> findStream(
+        dsl: DSL,
+        offset: Int? = null,
+        limit: Int? = null,
+        init: DSL.() -> JpqlQueryable<SelectQuery<T>>,
+    ): Stream<T?>
+
+    /**
+     * Returns all results of the select query.
+     */
+    @SinceJdsl("3.5.4")
+    fun <T : Any> findStream(
+        pageable: Pageable,
+        init: Jpql.() -> JpqlQueryable<SelectQuery<T>>,
+    ): Stream<T?>
+
+    /**
+     * Returns all results of the select query.
+     */
+    @SinceJdsl("3.5.4")
+    fun <T : Any, DSL : JpqlDsl> findStream(
+        dsl: JpqlDsl.Constructor<DSL>,
+        pageable: Pageable,
+        init: DSL.() -> JpqlQueryable<SelectQuery<T>>,
+    ): Stream<T?>
+
+    /**
+     * Returns all results of the select query.
+     */
+    @SinceJdsl("3.5.4")
+    fun <T : Any, DSL : JpqlDsl> findStream(
+        dsl: DSL,
+        pageable: Pageable,
+        init: DSL.() -> JpqlQueryable<SelectQuery<T>>,
+    ): Stream<T?>
+
     /**
      * Execute the update query.
      *