Question

使用RestKit，我试图映射以下JSON。

{
  "userID": 1,
  "collections": [
    {
      "collectionID": 120,
      "friends": [
        {
          "friendID": 6,
          "orders": [
            {
              "orderID": 1,
              "name": "Small"
            }
          ]
        }
      ]
    },
    {
      "collectionID": 123,
      "friends": [
        {
          "friendID": 6,
          "orders": [
            {
              "orderID": 2,
              "name": "Medium"
            }
          ]
        }
      ]
    }
  ]
}

我正在使用RestKit和MagicalRecord - 下面的设置代码，映射和关系

NSURL *modelURL = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"Model" ofType:@"momd"]];
NSManagedObjectModel *managedObjectModel = [[[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL] mutableCopy];
RKManagedObjectStore *managedObjectStore = [[RKManagedObjectStore alloc] initWithManagedObjectModel:managedObjectModel];
NSString *storePath = [RKApplicationDataDirectory() stringByAppendingPathComponent:@"db.sqlite"];

[managedObjectStore addSQLitePersistentStoreAtPath:storePath fromSeedDatabaseAtPath:nil withConfiguration:nil options:nil error:nil];
[managedObjectStore createManagedObjectContexts];

// Configure MagicalRecord to use RestKit's Core Data stack
[NSPersistentStoreCoordinator MR_setDefaultStoreCoordinator:managedObjectStore.persistentStoreCoordinator];
[NSManagedObjectContext MR_setRootSavingContext:managedObjectStore.persistentStoreManagedObjectContext];
[NSManagedObjectContext MR_setDefaultContext:managedObjectStore.mainQueueManagedObjectContext];

RKObjectManager *objectManager = [RKObjectManager managerWithBaseURL:[NSURL URLWithString:@"http://127.0.0.1:3500"]];
objectManager.managedObjectStore = managedObjectStore;

RKEntityMapping *appMapping = [RKEntityMapping mappingForEntityForName:@"App" inManagedObjectStore:managedObjectStore];
appMapping.identificationAttributes = @[ @"userID" ];

RKEntityMapping *collectionMapping = [RKEntityMapping mappingForEntityForName:@"Collection" inManagedObjectStore:managedObjectStore];
collectionMapping.identificationAttributes = @[ @"collectionID" ];
[collectionMapping addAttributeMappingsFromArray:@[@"collectionID"]];

RKEntityMapping *friendMapping = [RKEntityMapping mappingForEntityForName:@"Friend" inManagedObjectStore:managedObjectStore];
friendMapping.identificationAttributes = @[ @"friendID" ];
[friendMapping addAttributeMappingsFromArray:@[@"friendID"]];

RKEntityMapping *orderMapping = [RKEntityMapping mappingForEntityForName:@"Order" inManagedObjectStore:managedObjectStore];
orderMapping.identificationAttributes = @[ @"orderID" ];
[orderMapping addAttributeMappingsFromArray:@[@"orderID", @"name"]];


RKRelationshipMapping *appCollectionRelationship = [RKRelationshipMapping relationshipMappingFromKeyPath:@"collections" toKeyPath:@"collections" withMapping:collectionMapping];
[appMapping addPropertyMapping:appCollectionRelationship];

RKRelationshipMapping *collectionFriendRelationship = [RKRelationshipMapping relationshipMappingFromKeyPath:@"friends" toKeyPath:@"friends" withMapping:friendMapping];
[collectionMapping addPropertyMapping:collectionFriendRelationship];

RKRelationshipMapping *friendsOrderRelationship = [RKRelationshipMapping relationshipMappingFromKeyPath:@"orders" toKeyPath:@"orders" withMapping:orderMapping];
[friendsOrderRelationship setAssignmentPolicy:RKUnionAssignmentPolicy];
[friendMapping addPropertyMapping:friendsOrderRelationship];

然后，使用以下控制台查询我的API上的/ test路由（输出上面的JSON块）......

RKResponseDescriptor *responseDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:appMapping method:RKRequestMethodAny pathPattern:nil keyPath:nil statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];
[objectManager addResponseDescriptor:responseDescriptor];

[objectManager getObjectsAtPath:@"/test" parameters:nil success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {

    App *app = [mappingResult firstObject];
    for (Collection *collection in app.collections) {
        NSLog(@"collectionID = %@", collection.collectionID);
        for (Friend *friend in collection.friends) {
            NSLog(@"friendID = %@", friend.friendID);
            for (Order *order in friend.orders) {
                NSLog(@"Name = %@", order.name);
            }
        }
    }
} failure:^(RKObjectRequestOperation *operation, NSError *error) {}];

提供以下输出 - 请注意，名称都是中等，而不是一个小而另一个是中等。

collectionID = 120
friendID = 6
Name = Medium
Name = Small
collectionID = 123
friendID = 6
Name = Medium
Name = Small

为什么会这样？我猜它是因为朋友ID都是一样的，即使他们在不同的收藏品下......

Answer 1

这是因为您有identificationAttributes = @[ @"friendID" ];和关系的默认关系连接规则而不是替换。因此，第二个映射找到第一个映射创建的朋友，并替换订单关系内容。

您无法根据您显示的JSON实际更改唯一标识符，但您可能需要检查（与您的对象图要求相关）。

另外/或者，请参阅this answer，了解有关如何更改关系分配政策的详细信息，以便原始关系内容不会丢失。

RestKit嵌套关系

1 个答案: