RestKit：如何发布一组对象？

Question

问题摘要：

考虑一个与 KVC 兼容的类 SyncObject，其属性如下：time、someValue、<代码>lastChange，uuid。

考虑一个仅包含 SyncObject 实例的 NSArray。

我需要将数组作为 JSON 数组提交到服务器。

如何使用 RestKit 使用 HTTP POST 将此数组提交到服务器？

示例数组：

[
  {
    "time": "14:45 10/21/2011",
    "someValue": "15",
    "lastChange": "14:45 10/21/2011",
    "uuid": "0b07c510-f4c8-11e0-be50-0800200c9a66"
  },
  {
    "time": "14:50 10/21/2011",
    "someValue": "62",
    "lastChange": "14:51 10/21/2011",
    "uuid": "1a6d4480-f4c8-11e0-be50-0800200c9a66"
  }
]

---

详细信息

我有一个对象数组，我需要将其作为 JSON 发送到服务器。在我看来，RestKit 是最简单的方法：我试图避免将对象转换为一组 NSDictionary 对象，然后使用一些 JSON 编码器来获取 JSON，我可以 POST 到服务器。

因此，创建数组并设置数组中存储的对象类的映射后，我自然会尝试 POST 到服务器。

RKObjectManager* mgr = [RKObjectManager objectManagerWithBaseURL:@"http://localhost/someweb/api/"];
mgr.serializationMIMEType = RKMIMETypeFormURLEncoded;
mgr.client.username = @"username";
mgr.client.password = @"password";
RKObjectMapping* mapping = [RKObjectMapping mappingForClass:[NSMutableDictionary class]];
[mapping mapKeyPath: @"time"       toAttribute:@"time"         ];  
[mapping mapKeyPath: @"someValue"  toAttribute:@"someValue"    ];
[mapping mapKeyPath: @"lastChange" toAttribute:@"lastChange"   ];
[mapping mapKeyPath: @"uuid"       toAttribute:@"uuid"         ];
RKObjectMapping* mappingForSerialization = [mapping inverseMapping];
[mgr.mappingProvider setSerializationMapping:mappingForSerialization 
                                    forClass:[NSManagedObject class]];

[mgr.router routeClass:[NSManagedObject class] toResourcePath:@"/sync" forMethod:RKRequestMethodPOST];    

[mgr postObject:array delegate:nil/*self*/];

然而，这就是我得到的结果：

2011-10-11 14:57:51.769 AppConnect[1974:6e0b] *** Terminating app due to uncaught exception '(null)', reason: 'Unable to find a routable path for object of type '__NSArrayI' for HTTP Method 'POST''

显然，RestKit 不知道如何处理 NSArray。

如何使用 RestKit 发布一组对象？

---

我尝试了不同的方法：我用通过 RKObjectLoader 手动发送替换了最后一行。

//[mgr postObject:[NSMutableDictionary dictionaryWithObject:array forKey:@"data"] delegate:nil/*self*/];


NSString* syncPath = @"/sync"; 
RKObjectLoader * objectLoader = [mgr objectLoaderWithResourcePath:syncPath delegate:self];
objectLoader.serializationMIMEType = RKMIMETypeJSON;
objectLoader.method = RKRequestMethodPOST;
//objectLoader.objectClass = [NSManagedObject class];       
//objectLoader.managedObjectStore = mgr.objectStore; 
objectLoader.params = [NSDictionary dictionaryWithObject:array 
                                                  forKey:@"MyData"]; 
[objectLoader send];

不幸的是，这不应用任何类型的映射，而是传输对象描述的数组。设置serializationMIMEType也不会影响传输内容的结构，并且params始终以application/x-www-form-urlencoded的形式传输。

我还尝试分配序列化映射并将对象作为 targetObject 和 sourceObject 传递（这似乎是 RestKit 在 -[RKObjectManager postObject:delegate:]< 内部所做的事情/代码>）。

RKObjectLoader * objectLoader = [mgr objectLoaderWithResourcePath:syncPath delegate:self];
objectLoader.method = RKRequestMethodPOST;
//objectLoader.objectClass = [NSManagedObject class];       
//objectLoader.managedObjectStore = mgr.objectStore; 
objectLoader.params = [NSMutableDictionary dictionaryWithObject:array 
                                                  forKey:@"MyData"]; 
objectLoader.serializationMapping = mapping;
objectLoader.serializationMIMEType = RKMIMETypeJSON;
objectLoader.sourceObject = objectLoader.params;
objectLoader.targetObject = objectLoader.params;
[objectLoader send];

不幸的是，这样不会发生映射：

2011-10-12 12:36:48.143 MyProject[5119:207] D restkit.network:RKObjectLoader.m:290 POST or PUT request for source object {
    MyData =     (
        "<NSManagedObject: 0x5935430> (entity: SomeRecord; id: 0x5934da0 <x-coredata://64DF9977-DA50-4FCD-8C20-4132E58439BF/SomeRecord/p1> ; data: <fault>)",
        "<NSManagedObject: 0x5935730> (entity: SomeRecord; id: 0x5934db0 <x-coredata://64DF9977-DA50-4FCD-8C20-4132E58439BF/SomeRecord/p2> ; data: <fault>)"
    );
}, serializing to MIME Type application/json for transport...
2011-10-12 12:36:48.143 MyProject[5119:207] D restkit.object_mapping:RKObjectMappingOperation.m:428 Starting mapping operation...
2011-10-12 12:36:48.145 MyProject[5119:207] T restkit.object_mapping:RKObjectMappingOperation.m:291 Did not find mappable attribute value keyPath 'time'
2011-10-12 12:36:48.145 MyProject[5119:207] T restkit.object_mapping:RKObjectMappingOperation.m:291 Did not find mappable attribute value keyPath 'someValue'
2011-10-12 12:36:48.145 MyProject[5119:207] T restkit.object_mapping:RKObjectMappingOperation.m:291 Did not find mappable attribute value keyPath 'lastChange'
2011-10-12 12:36:48.145 MyProject[5119:207] T restkit.object_mapping:RKObjectMappingOperation.m:291 Did not find mappable attribute value keyPath 'uuid'
2011-10-12 12:36:48.145 MyProject[5119:207] D restkit.object_mapping:RKObjectMappingOperation.m:448 Mapping operation did not find any mappable content
2011-10-12 12:36:48.146 MyProject[5119:207] T restkit.network:RKRequest.m:211 Prepared POST URLRequest '<NSMutableURLRequest http://someurl/api/sync?request=provide_key>'. HTTP Headers: {
    Accept = "application/json";
    "Content-Length" = 0;
}. HTTP Body: .

Answer 1

Restkit 不为 NSArray 提供可路由路径，因为您为 NSManagedObject 类定义了路由。您可能想要创建一个自定义类，例如 MySyncEntity，它保存您在映射中定义的 ivars。然后，您可以像这样创建映射：

RKObjectMapping* mapping = [RKObjectMapping mappingForClass:[MySyncEntity class]];
....
[myManager setSerializationMIMEType:RKMIMETypeJSON];
[[myManager router] routeClass:[MySyncEntity class] toResourcePath:@"/sync"];

然后您应该能够将对象作为 JSON 对象发布到 API 后端。

进一步说明：

在本例中，我们希望将一组 NSManagedObject 实例发布到基于 JSON 的 API 中。为此，我们需要创建一个同步实体，将对象保存在数组中：

@interface MySyncEntity : NSObject {}
@property (nonatomic, retain) NSArray* mySyncArray;
...
@end 

mySyncArray 将保存我们想要提交到其余后端的有效负载。然后，我们为将在 mySyncArray 中发送的 NSManagedObject 和 MySyncEntity 实体本身创建适当的映射。

RKObjectManager *manager = [RKObjectManager objectManagerWithBaseURL:kBaseUrl];
...
RKObjectMapping *mngObjMapping = [RKObjectMapping mappingForClass:[NSManagedObject class]]; 
[mngObjMapping mapKeyPath: @"time" toAttribute:@"time"];  
[mngObjMapping mapKeyPath: @"recordLevel" toAttribute:@"recordLevel"];
.... //map as many properties as you wish
[[manager mappingProvider] setSerializationMapping:[mngObjMapping inverseMapping]
                                          forClass:[NSManagedObject class]];

//now, we create mapping for the MySyncEntity
RKObjectMapping *syncEntityMapping = [RKObjectMapping mappingForClass:[MySyncEntity class]];
[syncEntityMapping mapKeyPath:@"mySyncArray" toRelationship:@"mySyncArray" withMapping:mngObjMapping];
[[manager mappingProvider] setSerializationMapping:[syncEntityMapping inverseMapping]
                                          forClass:[MySyncEntity class]];

现在，定义映射后，我们可以将对象发布到服务器。

[manager postObject:mySyncInstance delegate:nil];

mySyncInstance 数组的内容将根据 mngObjMapping 进行映射，并发送到定义的其余端点。

Answer 2

作为进一步的澄清，我想指出 mja 的答案 关键是

[syncEntityMapping mapKeyPath:@"mySyncArray" toRelationship:@"mySyncArray" withMapping:mngObjMapping];

这说“mySyncArray keypath 是一个数组，其中包含应根据mngObjMapping”。