objective-c - RestKit - Hydrate 外键数组

Question

我有以下 JSON:

{
    "users": [
        {"id": "1", "name": "John Doe"},
        {"id": "2", "name": "Bill Nye"}
    ],
    "groups": [
        {"id": "1", "name": "Group1", "users": ["1", "2"]},
        {"id": "2", "name": "Group2", "users": ["1"]}
    ]
}

...以及带有用户和组对象的核心数据模型。组对象与用户之间存在一对多关系 (NSSet)。

我发现以下线程似乎表明这是可能的，但没有解释如何执行这种映射:

https://github.com/RestKit/RestKit/issues/284

如何执行此映射，以便正确连接每个组的“用户”关系？

注意:我设置了映射，可以将 JSON 用户和组正确映射到它们各自的核心数据对象。但是，每个组的“用户”NSSet 是空的。

Answer 1

所以，我使用 RestKit 0.20(pre2) 解决了这个问题。

JSON 需要更改为以下内容(注意组的用户数组中的属性名称):

{
    "users": [
        {"id": "1", "name": "John Doe"},
        {"id": "2", "name": "Bill Nye"}
    ],
    "groups": [
        {"id": "1", "name": "Group1", "users": [{"id" : "1"}, {"id" : "2"}]},
        {"id": "2", "name": "Group2", "users": [{"id" : "1"}]}
    ]
}

然后，下面的映射:

RKEntityMapping *userMapping = [RKEntityMapping mappingForEntityForName:@"User" inManagedObjectStore:managedObjectStore];
userMapping.identificationAttributes = @[@"id"];
[userMapping addAttributeMappingsFromArray:@[@"id", @"name"]];
RKEntityMapping *groupMapping = [RKEntityMapping mappingForEntityForName:@"Group" inManagedObjectStore:managedObjectStore];
groupMapping.identificationAttributes = @[@"id"];
[groupMapping addAttributeMappingsFromArray:@[@"id", @"name"]];
[groupMapping addRelationshipMappingWithSourceKeyPath:@"users" mapping:userMapping];

最后，以下 responseDescriptors:

RKResponseDescriptor *userResponseDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:classMapping pathPattern:@"/api/allthejson" keyPath:@"users" statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];
RKResponseDescriptor *groupResponseDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:classMapping pathPattern:@"/api/allthejson" keyPath:@"groups" statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];
[objectManager addResponseDescriptorsArray:@[userResponseDescriptor, groupResponseDescriptor]];

然后使用 RKObjectManager 的 getObjectsAtPath:parameters:success:failure 方法获取您的对象并完成!