feat: add api to get a user object without verifying they exist

Signed-off-by: Robin Appelman <robin@icewind.nl>

Author: icewind1991

lib/private/User/Manager.php

@@ -833,4 +833,8 @@ public function getSeenUsers(int $offset = 0, ?int $limit = null): \Iterator {
 			}
 		} while (count($userIds) === $batchSize && $limit !== 0);
 	}
+
+	public function getExistingUser(string $userId, ?string $displayName = null): IUser {
+		return new LazyUser($userId, $this, $displayName);
+	}
 }

lib/public/IUserManager.php

@@ -62,6 +62,9 @@ public function clearBackends();
 	/**
 	 * get a user by user id
 	 *
+	 * If you're already 100% sure that the user exists,
+	 * consider IUserManager::getExistingUser which has less overhead.
+	 *
 	 * @param string $uid
 	 * @return \OCP\IUser|null Either the user or null if the specified user does not exist
 	 * @since 8.0.0
@@ -246,4 +249,19 @@ public function getLastLoggedInUsers(?int $limit = null, int $offset = 0, string
 	 * @since 32.0.0
 	 */
 	public function getSeenUsers(int $offset = 0, ?int $limit = null): \Iterator;
+
+	/**
+	 * Get a user by user id without validating that the user exists.
+	 *
+	 * This should only be used if you're certain that the provided user id exists in the system.
+	 * Using this to get a user object for a non-existing user will lead to unexpected behavior down the line.
+	 *
+	 * If you're not 100% sure that the user exists, use IUserManager::get instead.
+	 *
+	 * @param string $userId
+	 * @param ?string $displayName If the display name is known in advance you can provide it so it doesn't have to be fetched again
+	 * @return IUser
+	 * @since 33.0.0
+	 */
+	public function getExistingUser(string $userId, ?string $displayName = null): IUser;
 }

tests/lib/User/ManagerTest.php

@@ -740,4 +740,26 @@ public function testGetByEmail(): void {
 		$this->assertEquals('uid1', $users[0]->getUID());
 		$this->assertEquals('uid2', $users[1]->getUID());
 	}
+
+	public function testGetExistingUser() {
+		$backend = $this->createMock(\Test\Util\User\Dummy::class);
+		$backend->method('userExists')
+			->with('foobar')
+			->willReturn(true);
+		$backend->method('getDisplayName')
+			->willReturn('Foo Bar');
+		$backend->method('implementsActions')
+			->willReturnCallback(fn (int $action) => $action === Backend::GET_DISPLAYNAME);
+
+		$manager = new Manager($this->config, $this->cacheFactory, $this->eventDispatcher, $this->logger);
+		$manager->registerBackend($backend);
+
+		$user = $manager->getExistingUser('foobar');
+		$this->assertEquals('foobar', $user->getUID());
+		$this->assertEquals('Foo Bar', $user->getDisplayName());
+
+		$user = $manager->getExistingUser('nobody', 'None');
+		$this->assertEquals('nobody', $user->getUID());
+		$this->assertEquals('None', $user->getDisplayName());
+	}
 }