From 432cdd7802b9d1109eb02925d45782b6c99b9e01 Mon Sep 17 00:00:00 2001
From: Brian Clozel <bclozel@pivotal.io>
Date: Wed, 15 Aug 2018 20:24:14 +0200
Subject: [PATCH] Add ResponseEntity.of(Optional) variant

When dealing with `Optional` values in a Controller handler (for
example, values coming from a Spring Data repository), developers might
reuse this code snippet quite often:

```
@GetMapping("/user")
public ResponseEntity<Optional<User>> fetchUser() {
  Optional<User> user = //...
  return user.map(ResponseEntity::ok).orElse(notFound().build());
}
```

This commit adds a new static method on `ResponseEntity` for that,
simplifying the previous snippet with `return ResponseEntity.of(user);`

Note that in case more specific HTTP response headers are required by
the application, developers should use other static methods to
explicitly tell  which headers should be used in each case.

Issue: SPR-17187
---
 .../springframework/http/ResponseEntity.java  | 13 +++++++++++
 .../http/ResponseEntityTests.java             | 22 ++++++++++++++++++-
 2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/spring-web/src/main/java/org/springframework/http/ResponseEntity.java b/spring-web/src/main/java/org/springframework/http/ResponseEntity.java
index 964f751e42..65c94c3b9b 100644
--- a/spring-web/src/main/java/org/springframework/http/ResponseEntity.java
+++ b/spring-web/src/main/java/org/springframework/http/ResponseEntity.java
@@ -19,6 +19,7 @@ package org.springframework.http;
 import java.net.URI;
 import java.util.Arrays;
 import java.util.LinkedHashSet;
+import java.util.Optional;
 import java.util.Set;
 
 import org.springframework.lang.Nullable;
@@ -213,6 +214,18 @@ public class ResponseEntity<T> extends HttpEntity<T> {
 		return new DefaultBuilder(status);
 	}
 
+	/**
+	 * A shortcut for creating a {@code ResponseEntity} with the given body
+	 * and the {@linkplain HttpStatus#OK OK} status, or an empty body and a
+	 * {@linkplain HttpStatus#NOT_FOUND NOT FOUND} status in case of a
+	 * {@linkplain Optional#empty()} parameter.
+	 * @return the created {@code ResponseEntity}
+	 * @since 5.1
+	 */
+	public static <T> ResponseEntity<T> of(Optional<T> body) {
+		return body.map(ResponseEntity::ok).orElse(notFound().build());
+	}
+
 	/**
 	 * Create a builder with the status set to {@linkplain HttpStatus#OK OK}.
 	 * @return the created builder
diff --git a/spring-web/src/test/java/org/springframework/http/ResponseEntityTests.java b/spring-web/src/test/java/org/springframework/http/ResponseEntityTests.java
index 07ef76f89b..ec3414638f 100644
--- a/spring-web/src/test/java/org/springframework/http/ResponseEntityTests.java
+++ b/spring-web/src/test/java/org/springframework/http/ResponseEntityTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -19,6 +19,7 @@ package org.springframework.http;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.util.List;
+import java.util.Optional;
 import java.util.concurrent.TimeUnit;
 
 import org.hamcrest.Matchers;
@@ -72,6 +73,25 @@ public class ResponseEntityTests {
 		assertEquals(entity, responseEntity.getBody());
 	}
 
+	@Test
+	public void ofOptional() {
+		Integer entity = 42;
+		ResponseEntity<Integer> responseEntity = ResponseEntity.of(Optional.of(entity));
+
+		assertNotNull(responseEntity);
+		assertEquals(HttpStatus.OK, responseEntity.getStatusCode());
+		assertEquals(entity, responseEntity.getBody());
+	}
+
+	@Test
+	public void ofEmptyOptional() {
+		ResponseEntity<Integer> responseEntity = ResponseEntity.of(Optional.empty());
+
+		assertNotNull(responseEntity);
+		assertEquals(HttpStatus.NOT_FOUND, responseEntity.getStatusCode());
+		assertNull(responseEntity.getBody());
+	}
+
 	@Test
 	public void createdLocation() throws URISyntaxException {
 		URI location = new URI("location");