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假设我想用 json 向服务器发送请求

{ "begin_session" : { "info" : "this is some info" } }

我期望响应json：

{ "token" : "this is a token", "a_objects" : [
    { "name" : "name of first a_object", "b_objects" : [
        { "name" : "name of first b_object", "type" : "some type value", "id" : "123" },
        { "name" : "name of second b_object", "type" : "some other type value", "id" : "124" }
    ], "id" : "id of first a_object" },
    { "name" : "name of second a_object", "b_objects" : [
        { "name" : "name of first b_object", "type" : "some type value", "id" : "123" },
        { "name" : "name of third b_object", "type" : "some third type value" , "id" : "125" },
    ], "id" : "id of second a_object" }
] }

我想暂时存储“令牌”并将 a_objects 持久保存在核心数据中。这是我应该如何做整个过程吗？首先，我设置了对象：

@interface LoginToken : NSObject
    @property (nonatomic, copy) NSString *token;
@end

@interface AObject : NSManagedObject
    @property (nonatomic, retain) NSString *name;
    @property (nonatomic, retain) NSSet *bObjects;
    @property (nonatomic, retain) NSString *aObjectId;
@end

@implementation AObject
    @dynamic name; @dynamic bObjects; @dynamic aObjectId;
@end

@interface BObject : NSManagedObject
    @property (nonatomic, retain) NSString *name;
    @property (nonatomic, retain) AObject *aObject;
    @property (nonatomic, retain) NSString *type;
    @property (nonatomic, retain) NSString *bObjectId;
@end

@implementation BObject
    @dynamic name; @dynamic aObject; @dynamic type; @dynamic bObjectId;
@end

这些是请求参数：

NSDictionary *params = @{"begin_session":@{@"info":@"this is some info"}};

然后我设置映射：

RKObjectMapping *tokenMapping = [RKObjectMapping mappingForClass:[LoginToken class]];
[tokenMapping addAttributeMappingsFromArray:@[@"token"]];
RKResponseDescriptor *tokenResponseDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:tokenMapping pathPattern:nil keyPath:@"token" statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];

RKEntityMapping *bObjectMapping = [RKEntityMapping mappingForEntityForName:@"BObject" inManagedObjectStore:objectManager.managedObjectStore];
[bObjectMapping addAttributeMappingsFromDictionary:@{@"name":@"name",@"type":@"type", @"id":@"bObjectId"}];
bObjectMapping.identificationAttributes = @[@"bObjectId"];

RKEntityMapping *aObjectMapping = [RKEntityMapping mappingForEntityForName:@"AObject" inManagedObjectStore:objectManager.managedObjectStore];
[aObjectMapping addAttributeMappingsFromDictionary:@{@"name":@"name",@"id":@"aObjectId"}];
[aObjectMapping addPropertyMapping:[RKRelationshipMapping relationshipMappingFromKeyPath:@"b_objects" toKeyPath:@"bObjects" withMapping:bObjectMapping]];
aObjectMapping.identificationAttributes = @[@"aObjectId"];

假设objectManager是一个正确配置的 RKObjectManager。我设置了响应描述符：

RKResponseDescriptor *tokenResponseDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:tokenMapping pathPattern:nil keyPath:@"token" statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];

RKResponseDescriptor *aObjectResponseDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:aObjectMapping pathPattern:nil keyPath:@"a_objects" statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];

[objectManager addResponseDescriptorsFromArray:@[tokenResponseDescriptor, aObjectResponseDescriptor]];

最后我会提出请求：

[objectManager getObjectsAtPath:@"path" parameters:params success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {
    LoginToken *token = [mappingResult firstObject]; // use this token transiently
    // coredata objects are auto saved
} failure:^(RKObjectRequestOperation *operation, NSError *error) {
    // handle error
}];

如果这实际上是正确的方法，我需要注意什么吗？另外，如何设置从 BObject 到 AObject 的反向关系...？

4

1 回答 1

0

只要您的 CoreData 文件正确配置了关系（根据您的对象头文件看起来正确），那么映射器就会处理反向关系。否则，它应该按原样工作。

请注意，令牌对象也将保留在 CoreData 中，因此您可能必须删除它们，这是所需的行为。

于 2013-10-18T17:03:07.403 回答