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Restkit 0.20:POST CoreData与外键的关系

restkit-0.20 foreign-key-relationship restkit ios

Dirk van Oosterbosch · 技术社区 · 11 年前

我在RestKit和CoreData方面有点吃力,尤其是因为RestKit 0.20的例子和文档太少了。

我有一个(托管)对象 Song 与多对一的关系 Album 。以下代码可以发布JSON,但不能在 压扁的 格式,服务器会例外。

// Defined elsewhere
Album *theAlbum;
RKObjectManager *objMan = [self objectManager];

// Response Mapping
RKObjectMapping *responseMapping = [RKObjectMapping mappingForClass:[Song class]];
[responseMapping addAttributeMappingsFromDictionary:@{ @"song": @"songID" }];
NSIndexSet *statusCodes = RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful);
RKResponseDescriptor *responseDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:responseMapping
                                                                                   pathPattern:@"/api/song"
                                                                                       keyPath:nil
                                                                                   statusCodes:statusCodes];

// Request Mapping
RKObjectMapping *requestMapping = [RKObjectMapping requestMapping];
RKEntityMapping *albumRelationshipMapping = [RKEntityMapping mappingForEntityForName:@"Album" inManagedObjectStore:[objMan managedObjectStore]];
[albumRelationshipMapping addAttributeMappingsFromDictionary:@{@"id": @"albumID", }];
[requestMapping addAttributeMappingsFromDictionary:@{ @"title": @"title", @"length": @"length" }];
[requestMapping addPropertyMapping:[RKRelationshipMapping relationshipMappingFromKeyPath:@"album"
                                                                               toKeyPath:@"album"
                                                                             withMapping:albumRelationshipMapping]];
requestMapping = [requestMapping inverseMapping];
RKRequestDescriptor *requestDescriptor = [RKRequestDescriptor requestDescriptorWithMapping:requestMapping objectClass:[Song class] rootKeyPath:nil];

[objMan addRequestDescriptor:requestDescriptor];
[objMan addResponseDescriptor:responseDescriptor];

// Create a new temporary song object
Song *song = [NSEntityDescription insertNewObjectForEntityForName:@"Song"
                                                inManagedObjectContext:[[objMan managedObjectStore] mainQueueManagedObjectContext]];
song.title = @"Some Title";
song.length = 123;
song.album = theAlbum;

// Post operation
objMan.requestSerializationMIMEType = RKMIMETypeJSON;
RKManagedObjectRequestOperation *operation = [objMan appropriateObjectRequestOperationWithObject:song
                                                                                          method:RKRequestMethodPOST
                                                                                            path:@"/api/song"
                                                                                      parameters:nil];
[operation setCompletionBlockWithSuccess:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {
    // Success
} failure:^(RKObjectRequestOperation *operation, NSError *error) {
    // Failure
}];
[objMan enqueueObjectRequestOperation:operation];

这段代码将发布一个JSON正文,如下所示:

{"title":"Some Title","length":"123","album":{"id":"6e32ae476815f365"}}

但是,服务器需要这样的JSON主体:

{"title":"Some Title","length":"123","album":"6e32ae476815f365"}

即关系 album 应该是 压扁的 外键而不是嵌套对象。但当我试图改变 albumRelationshipMapping 这样地:

[albumRelationshipMapping setIdentificationAttributes:@[ @"albumID" ]];
[albumRelationshipMapping addAttributeMappingToKeyOfRepresentationFromAttribute:@"albumID"];

它抛出一个异常。 ( NSInvalidArgumentException', reason: '*** -[NSProxy doesNotRecognizeSelector:allKeys] called!' )

有人知道我在这里做错了什么吗?或者有没有示例代码可以引导我朝着正确的方向前进?

很抱歉,如果这个问题已经在其他地方得到了回答。我搜索了所有的stackoverflow和谷歌群组,但找不到适合我的案例的特定解决方案(RestKit 0.20,CoreData,仅与FK的关系)。

谢谢,德克

1 回复 | 直到 11 年前

JD_ 11 年前

在这种情况下,我认为您可以简单地使用点号直接获取白蛋白ID(无需使用RKRelationshipMapping)

尝试以这种方式更新代码:

// Request Mapping
RKObjectMapping *requestMapping = [RKObjectMapping requestMapping];
RKEntityMapping *albumRelationshipMapping = [RKEntityMapping mappingForEntityForName:@"Album" inManagedObjectStore:[objMan managedObjectStore]];
//[albumRelationshipMapping addAttributeMappingsFromDictionary:@{@"id": @"albumID", }];
//[requestMapping addAttributeMappingsFromDictionary:@{ @"title": @"title", @"length": @"length" }];
[requestMapping addAttributeMappingsFromDictionary:@{ @"title": @"title", @"length": @"length", @"album" : @"album.albumID" }];
//[requestMapping addPropertyMapping:[RKRelationshipMapping relationshipMappingFromKeyPath:@"album"
//                                                                               toKeyPath:@"album"
//                                                                             withMapping:albumRelationshipMapping]];