DATAMONGO-2086 - Fix Fluent API Kotlin extension generics to allow projections.

We now fixed Kotlin extension generics to properly use projections by ignoring the source type of the Fluent API object. Previously, the source and target type were linked which prevented the use of a different result type.

Original Pull Request: #609

spring-data-mongodb/src/main/kotlin/org/springframework/data/mongodb/core/ExecutableFindOperationExtensions.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017 the original author or authors.
+ * Copyright 2017-2018 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.
@@ -37,7 +37,6 @@ fun <T : Any> ExecutableFindOperation.query(entityClass: KClass<T>): ExecutableF
 inline fun <reified T : Any> ExecutableFindOperation.query(): ExecutableFindOperation.ExecutableFind<T> =
 		query(T::class.java)
 
-
 /**
  * Extension for [ExecutableFindOperation.FindWithProjection. as] providing a [KClass] based variant.
  *
@@ -45,7 +44,7 @@ inline fun <reified T : Any> ExecutableFindOperation.query(): ExecutableFindOper
  * @author Mark Paluch
  * @since 2.0
  */
-fun <T : Any> ExecutableFindOperation.FindWithProjection<T>.asType(resultType: KClass<T>): ExecutableFindOperation.FindWithQuery<T> =
+fun <T : Any> ExecutableFindOperation.FindWithProjection<*>.asType(resultType: KClass<T>): ExecutableFindOperation.FindWithQuery<T> =
 		`as`(resultType.java)
 
 /**
@@ -55,7 +54,7 @@ fun <T : Any> ExecutableFindOperation.FindWithProjection<T>.asType(resultType: K
  * @author Mark Paluch
  * @since 2.0
  */
-inline fun <reified T : Any> ExecutableFindOperation.FindWithProjection<T>.asType(): ExecutableFindOperation.FindWithQuery<T> =
+inline fun <reified T : Any> ExecutableFindOperation.FindWithProjection<*>.asType(): ExecutableFindOperation.FindWithQuery<T> =
 		`as`(T::class.java)
 
 /**

spring-data-mongodb/src/main/kotlin/org/springframework/data/mongodb/core/ReactiveFindOperationExtensions.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017 the original author or authors.
+ * Copyright 2017-2018 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.
@@ -41,7 +41,7 @@ inline fun <reified T : Any> ReactiveFindOperation.query(): ReactiveFindOperatio
  * @author Mark Paluch
  * @since 2.0
  */
-fun <T : Any> ReactiveFindOperation.FindWithProjection<T>.asType(resultType: KClass<T>): ReactiveFindOperation.FindWithQuery<T> =
+fun <T : Any> ReactiveFindOperation.FindWithProjection<*>.asType(resultType: KClass<T>): ReactiveFindOperation.FindWithQuery<T> =
 		`as`(resultType.java)
 
 /**
@@ -50,7 +50,7 @@ fun <T : Any> ReactiveFindOperation.FindWithProjection<T>.asType(resultType: KCl
  * @author Mark Paluch
  * @since 2.0
  */
-inline fun <reified T : Any> ReactiveFindOperation.FindWithProjection<T>.asType(): ReactiveFindOperation.FindWithQuery<T> =
+inline fun <reified T : Any> ReactiveFindOperation.FindWithProjection<*>.asType(): ReactiveFindOperation.FindWithQuery<T> =
 		`as`(T::class.java)
 
 /**

spring-data-mongodb/src/test/kotlin/org/springframework/data/mongodb/core/ExecutableFindOperationExtensionsTests.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017 the original author or authors.
+ * Copyright 2017-2018 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.
@@ -53,24 +53,24 @@ class ExecutableFindOperationExtensionsTests {
         verify(operation).query(First::class.java)
     }
 
-    @Test // DATAMONGO-1689
+    @Test // DATAMONGO-1689, DATAMONGO-2086
     fun `ExecutableFindOperation#FindOperationWithProjection#asType(KClass) extension should call its Java counterpart`() {
 
-        operationWithProjection.asType(First::class)
-        verify(operationWithProjection).`as`(First::class.java)
+        operationWithProjection.asType(User::class)
+        verify(operationWithProjection).`as`(User::class.java)
     }
 
-    @Test // DATAMONGO-1689
+    @Test // DATAMONGO-1689, DATAMONGO-2086
     fun `ExecutableFindOperation#FindOperationWithProjection#asType() with reified type parameter extension should call its Java counterpart`() {
 
-        operationWithProjection.asType()
-        verify(operationWithProjection).`as`(First::class.java)
+        operationWithProjection.asType<User>()
+        verify(operationWithProjection).`as`(User::class.java)
     }
 
-    @Test // DATAMONGO-1761
+    @Test // DATAMONGO-1761, DATAMONGO-2086
     fun `ExecutableFindOperation#DistinctWithProjection#asType(KClass) extension should call its Java counterpart`() {
 
-        distinctWithProjection.asType(First::class)
-        verify(distinctWithProjection).`as`(First::class.java)
+        distinctWithProjection.asType(User::class)
+        verify(distinctWithProjection).`as`(User::class.java)
     }
 }

spring-data-mongodb/src/test/kotlin/org/springframework/data/mongodb/core/ReactiveFindOperationExtensionsTests.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017 the original author or authors.
+ * Copyright 2017-2018 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.
@@ -52,24 +52,24 @@ class ReactiveFindOperationExtensionsTests {
 		verify(operation).query(First::class.java)
 	}
 
-	@Test // DATAMONGO-1719
+	@Test // DATAMONGO-1719, DATAMONGO-2086
 	fun `ReactiveFind#FindOperatorWithProjection#asType(KClass) extension should call its Java counterpart`() {
 
-		operationWithProjection.asType(First::class)
-		verify(operationWithProjection).`as`(First::class.java)
+		operationWithProjection.asType(User::class)
+		verify(operationWithProjection).`as`(User::class.java)
 	}
 
-	@Test // DATAMONGO-1719
+	@Test // DATAMONGO-1719, DATAMONGO-2086
 	fun `ReactiveFind#FindOperatorWithProjection#asType() with reified type parameter extension should call its Java counterpart`() {
 
-		operationWithProjection.asType()
-		verify(operationWithProjection).`as`(First::class.java)
+		operationWithProjection.asType<User>()
+		verify(operationWithProjection).`as`(User::class.java)
 	}
 
-	@Test // DATAMONGO-1761
+	@Test // DATAMONGO-1761, DATAMONGO-2086
 	fun `ReactiveFind#DistinctWithProjection#asType(KClass) extension should call its Java counterpart`() {
 
-		distinctWithProjection.asType(First::class)
-		verify(distinctWithProjection).`as`(First::class.java)
+		distinctWithProjection.asType(User::class)
+		verify(distinctWithProjection).`as`(User::class.java)
 	}
 }