Merge pull request #23070 from L00kian/23060-fix

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/RequestPartMethodArgumentResolver.java

 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -96,19 +96,12 @@ public class RequestPartMethodArgumentResolver extends AbstractMessageReaderArgu
 
 		ReactiveAdapter adapter = getAdapterRegistry().getAdapter(parameter.getParameterType());
 		if (adapter != null) {
-			// Mono<Part> or Flux<Part>
 			MethodParameter elementType = parameter.nested();
-			if (Part.class.isAssignableFrom(elementType.getNestedParameterType())) {
-				parts = (adapter.isMultiValue() ? parts : parts.take(1));
-				return Mono.just(adapter.fromPublisher(parts));
-			}
-			// We have to decode the content for each part, one at a time
-			if (adapter.isMultiValue()) {
-				return Mono.just(decodePartValues(parts, elementType, bindingContext, exchange, isRequired));
-			}
+			return Mono.just(adapter.fromPublisher(
+					Part.class.isAssignableFrom(elementType.getNestedParameterType()) ?
+							parts : decodePartValues(parts, elementType, bindingContext, exchange, isRequired)));
 		}
 
-		// <T> or Mono<T>
 		return decodePartValues(parts, parameter, bindingContext, exchange, isRequired)
 				.next().cast(Object.class);
 	}

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/RequestPartMethodArgumentResolverTests.java

 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -53,13 +53,18 @@ import org.springframework.web.reactive.BindingContext;
 import org.springframework.web.server.ServerWebExchange;
 import org.springframework.web.server.ServerWebInputException;
 
-import static org.junit.Assert.*;
-import static org.springframework.core.ResolvableType.*;
-import static org.springframework.web.method.MvcAnnotationPredicates.*;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+import static org.springframework.core.ResolvableType.forClass;
+import static org.springframework.web.method.MvcAnnotationPredicates.requestPart;
 
 /**
  * Unit tests for {@link RequestPartMethodArgumentResolver}.
  * @author Rossen Stoyanchev
+ * @author Ilya Lukyanovich
  */
 public class RequestPartMethodArgumentResolverTests {
 
@@ -131,6 +136,15 @@ public class RequestPartMethodArgumentResolverTests {
 		assertEquals("James", actual.get(1).getName());
 	}
 
+	@Test // gh-23060
+	public void listPersonNotRequired() {
+		MethodParameter param = this.testMethod.annot(requestPart().notRequired()).arg(List.class, Person.class);
+		MultipartBodyBuilder bodyBuilder = new MultipartBodyBuilder();
+		List<Person> actual = resolveArgument(param, bodyBuilder);
+
+		assertEquals(Collections.emptyList(), actual);
+	}
+
 	@Test
 	public void monoPerson() {
 		MethodParameter param = this.testMethod.annot(requestPart()).arg(Mono.class, Person.class);
@@ -141,6 +155,15 @@ public class RequestPartMethodArgumentResolverTests {
 		assertEquals("Jones", actual.block().getName());
 	}
 
+	@Test // gh-23060
+	public void monoPersonNotRequired() {
+		MethodParameter param = this.testMethod.annot(requestPart().notRequired()).arg(Mono.class, Person.class);
+		MultipartBodyBuilder bodyBuilder = new MultipartBodyBuilder();
+		Mono<Person> actual = resolveArgument(param, bodyBuilder);
+
+		assertNull(actual.block());
+	}
+
 	@Test
 	public void fluxPerson() {
 		MethodParameter param = this.testMethod.annot(requestPart()).arg(Flux.class, Person.class);
@@ -154,6 +177,15 @@ public class RequestPartMethodArgumentResolverTests {
 		assertEquals("James", persons.get(1).getName());
 	}
 
+	@Test // gh-23060
+	public void fluxPersonNotRequired() {
+		MethodParameter param = this.testMethod.annot(requestPart().notRequired()).arg(Flux.class, Person.class);
+		MultipartBodyBuilder bodyBuilder = new MultipartBodyBuilder();
+		Flux<Person> actual = resolveArgument(param, bodyBuilder);
+
+		assertEquals(Collections.emptyList(), actual.collectList().block());
+	}
+
 	@Test
 	public void part() {
 		MethodParameter param = this.testMethod.annot(requestPart()).arg(Part.class);
@@ -177,6 +209,15 @@ public class RequestPartMethodArgumentResolverTests {
 		assertEquals("{\"name\":\"James\"}", partToUtf8String(actual.get(1)));
 	}
 
+	@Test // gh-23060
+	public void listPartNotRequired() {
+		MethodParameter param = this.testMethod.annot(requestPart().notRequired()).arg(List.class, Part.class);
+		MultipartBodyBuilder bodyBuilder = new MultipartBodyBuilder();
+		List<Part> actual = resolveArgument(param, bodyBuilder);
+
+		assertEquals(Collections.emptyList(), actual);
+	}
+
 	@Test
 	public void monoPart() {
 		MethodParameter param = this.testMethod.annot(requestPart()).arg(Mono.class, Part.class);
@@ -188,6 +229,15 @@ public class RequestPartMethodArgumentResolverTests {
 		assertEquals("{\"name\":\"Jones\"}", partToUtf8String(part));
 	}
 
+	@Test // gh-23060
+	public void monoPartNotRequired() {
+		MethodParameter param = this.testMethod.annot(requestPart().notRequired()).arg(Mono.class, Part.class);
+		MultipartBodyBuilder bodyBuilder = new MultipartBodyBuilder();
+		Mono<Part> actual = resolveArgument(param, bodyBuilder);
+
+		assertNull(actual.block());
+	}
+
 	@Test
 	public void fluxPart() {
 		MethodParameter param = this.testMethod.annot(requestPart()).arg(Flux.class, Part.class);
@@ -201,6 +251,15 @@ public class RequestPartMethodArgumentResolverTests {
 		assertEquals("{\"name\":\"James\"}", partToUtf8String(parts.get(1)));
 	}
 
+	@Test // gh-23060
+	public void fluxPartNotRequired() {
+		MethodParameter param = this.testMethod.annot(requestPart().notRequired()).arg(Flux.class, Part.class);
+		MultipartBodyBuilder bodyBuilder = new MultipartBodyBuilder();
+		Flux<Part> actual = resolveArgument(param, bodyBuilder);
+
+		assertEquals(Collections.emptyList(), actual.collectList().block());
+	}
+
 	@Test
 	public void personRequired() {
 		MethodParameter param = this.testMethod.annot(requestPart()).arg(Person.class);
@@ -278,7 +337,13 @@ public class RequestPartMethodArgumentResolverTests {
 			@RequestPart("name") Flux<Part> partFlux,
 			@RequestPart("name") List<Part> partList,
 			@RequestPart(name = "anotherPart", required = false) Person anotherPerson,
+			@RequestPart(name = "name", required = false) Mono<Person> anotherPersonMono,
+			@RequestPart(name = "name", required = false) Flux<Person> anotherPersonFlux,
+			@RequestPart(name = "name", required = false) List<Person> anotherPersonList,
 			@RequestPart(name = "anotherPart", required = false) Part anotherPart,
+			@RequestPart(name = "name", required = false) Mono<Part> anotherPartMono,
+			@RequestPart(name = "name", required = false) Flux<Part> anotherPartFlux,
+			@RequestPart(name = "name", required = false) List<Part> anotherPartList,
 			Person notAnnotated) {}