如何使用 Restkit 0.20.0 创建/发布新的托管对象到服务器？

Question

我很难找到有关创建新托管对象、设置其值以及使用 Restkit 保存到服务器的文档或示例。

我有一个 NSManagedObject 帖子：

@interface Post : NSManagedObject

@property (nonatomic, retain) NSNumber * postID;
@property (nonatomic, retain) NSString * title;
@property (nonatomic, retain) NSString * text;

@end

这是我的 AppDelegate 设置：

// ---- BEGIN RestKit setup -----
RKLogConfigureByName("RestKit/Network", RKLogLevelTrace);

NSError *error = nil;
NSURL *modelURL = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"My_App" ofType:@"momd"]];
// NOTE: Due to an iOS 5 bug, the managed object model returned is immutable.
NSManagedObjectModel *managedObjectModel = [[[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL] mutableCopy];
RKManagedObjectStore *managedObjectStore = [[RKManagedObjectStore alloc] initWithManagedObjectModel:managedObjectModel];

// Enable Activity Indicator Spinner
[AFNetworkActivityIndicatorManager sharedManager].enabled = YES;

// Initialize the Core Data stack
[managedObjectStore createPersistentStoreCoordinator];

NSPersistentStore __unused *persistentStore = [managedObjectStore addInMemoryPersistentStore:&error];
NSAssert(persistentStore, @"Failed to add persistent store: %@", error);

[managedObjectStore createManagedObjectContexts];

// Configure a managed object cache to ensure we do not create duplicate objects
managedObjectStore.managedObjectCache = [[RKInMemoryManagedObjectCache alloc] initWithManagedObjectContext:managedObjectStore.persistentStoreManagedObjectContext];

// Set the default store shared instance
[RKManagedObjectStore setDefaultStore:managedObjectStore];

// Configure the object manager
RKObjectManager *objectManager = [RKObjectManager managerWithBaseURL:[NSURL URLWithString:@"http://localhost:3000/api/v1"]];
objectManager.managedObjectStore = managedObjectStore;
NSString *auth_token = [[LUKeychainAccess standardKeychainAccess] stringForKey:@"auth_token"];  // Getting the Auth_Token from keychain
[objectManager.HTTPClient  setAuthorizationHeaderWithToken:auth_token];

[RKObjectManager setSharedManager:objectManager];

// Setup Post entity mappping
RKEntityMapping *postMapping = [RKEntityMapping mappingForEntityForName:@"Post" inManagedObjectStore:managedObjectStore];
[postMapping addAttributeMappingsFromDictionary:@{
 @"title":             @"title",
 @"text":       @"text",
 @"id":         @"postID"}];

RKResponseDescriptor *postResponseDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:postMapping pathPattern:nil keyPath:@"post" statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];
[objectManager addResponseDescriptor:postResponseDescriptor];

现在，在我的 NewPostViewController 中，当我单击导航栏中的“保存”按钮时，我需要做什么才能将此帖子保存到我的服务器？

这是我尝试过的，但它无法正常工作。我输入了成功块，我的服务器收到了 POST，但字段为零：

- (void)savePost {
    RKManagedObjectStore *objectStore = [[RKObjectManager sharedManager] managedObjectStore];
    Post *post = [NSEntityDescription insertNewObjectForEntityForName:@"Post" inManagedObjectContext:objectStore.mainQueueManagedObjectContext];
    [post setTitle:@"The Title"];
    [post setText:@"The Text"];

    [[RKObjectManager sharedManager] postObject:post path:@"posts" parameters:nil success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {
        NSLog(@"Success saving post");
    } failure:^(RKObjectRequestOperation *operation, NSError *error) {
        NSLog(@"Failure saving post: %@", error.localizedDescription);
    }];
}

Answer 1

您似乎没有将任何 RKRequestDescriptor 添加到您的对象管理器中。没有它们，可怜的对象管理器就无法使用键/值魔法将您的对象序列化为 NSDictionary。

您添加的 RKResponseDescriptor 描述了如何管理响应。这就是为什么您会看到名为的成功块：RestKit 不知道您要发送什么，但它可以识别服务器响应中的 Post 对象。

尝试在您的 responseDescriptor 代码下方添加：

RKRequestDescriptor * requestDescriptor = [RKRequestDescriptor requestDescriptorWithMapping:[postMapping inverseMapping] objectClass:[Post class] rootKeyPath:@"post"];
[objectManager addRequestDescriptor:requestDescriptor];

（仔细检查密钥路径；我不知道您的 API 期望什么，所以我选择了响应描述符中的内容）