Question

我是CoreData和Restkit的新手，我在遇到以下错误时遇到了很多麻烦。

我正在使用restkit来解析Foursquare返回的一些场地。不幸的是我一直收到这个错误：

2013-07-12 16:12:46.369 FlokMobile[5903:c07] CoreData: error: Serious application error.  Exception was caught during Core Data change processing.  This is usually a bug within an observer of NSManagedObjectContextObjectsDidChangeNotification.  [<FoursquareVenue 0x1ec5fb00> valueForUndefinedKey:]: the entity Venue is not key value coding-compliant for the key "distance". with userInfo {
    NSTargetObjectUserInfoKey = "<FoursquareVenue: 0x1ec5fb00> (entity: Venue; id: 0xb472c10 <x-coredata://EAB387D9-C6CB-4873-84C5-1C32E137FFE9/Venue/p49> ; data: {\n    canonicalUrl = \"https://foursquare.com/v/sams-cable-car-lounge/5171ef7b498e4035a7f7a371\";\n    location = \"0xb477860 <x-coredata://EAB387D9-C6CB-4873-84C5-1C32E137FFE9/Location/p30>\";\n    name = \"Sam's Cable Car Lounge\";\n    venueID = 5171ef7b498e4035a7f7a371;\n})";
    NSUnknownUserInfoKey = distance;
}
2013-07-12 16:12:46.370 FlokMobile[5903:c07] *** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<FoursquareVenue 0x1ec5fb00> valueForUndefinedKey:]: the entity Venue is not key value coding-compliant for the key "distance".'
*** First throw call stack:
(0x1e42012 0x1c67e7e 0x1ecafb1 0x24d1d4 0x168000b 0x1e8fc4 0x169e247 0x1738c62 0x2af8a5 0x2aa735 0x2ad011 0x17284f9 0x1e9c0c5 0x1df6efa 0x165cbb2 0x1bf163 0x258d2f 0x1ba596 0x1b9869 0x1e6558 0x25b025 0x1e0cc1 0x2697731 0x26a6014 0x26967d5 0x1de8af5 0x1de7f44 0x1de7e1b 0x28dd7e3 0x28dd668 0xbabffc 0x2e7d 0x2da5)
libc++abi.dylib: terminate called throwing an exception

以下是我用来设置密钥映射的代码：

// Setup Restkit for Foursquare

//Setup mapping for response
NSError *error = nil;
NSURL *modelURL = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"FoursquareModel" ofType:@"momd"]];
//mutableCopy might not be necessary
NSManagedObjectModel *managedObjectModel = [[[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL] mutableCopy];
RKManagedObjectStore *managedObjectStore = [[RKManagedObjectStore alloc] initWithManagedObjectModel:managedObjectModel];

//Initialize Core Data stack
[managedObjectStore createPersistentStoreCoordinator];

NSPersistentStore __unused *persistentStore = [managedObjectStore addInMemoryPersistentStore:&error];
NSAssert(persistentStore, @"Failed to add persistent store: %@", error);

[managedObjectStore createManagedObjectContexts];

//Set default store shared instance
[RKManagedObjectStore setDefaultStore:managedObjectStore];

//Configure Object Manager
RKObjectManager *objectManager = [RKObjectManager managerWithBaseURL:[NSURL URLWithString:@"https://api.foursquare.com/v2/"]];
objectManager.managedObjectStore = managedObjectStore;

[RKObjectManager setSharedManager:objectManager];

RKEntityMapping *venueMapping = [RKEntityMapping mappingForEntityForName:@"Venue" inManagedObjectStore:managedObjectStore];
RKEntityMapping *locationMapping = [RKEntityMapping mappingForEntityForName:@"Location" inManagedObjectStore:managedObjectStore];

[venueMapping addAttributeMappingsFromDictionary:@{
 @"name":         @"name",
 @"id":           @"venueID",
 @"canonicalUrl": @"canonicalUrl"}];
venueMapping.identificationAttributes = @[@"venueID"];

[locationMapping addAttributeMappingsFromArray:@[ @"address",@"cc",@"city",@"country",@"crossStreet",@"distance",@"lat",@"lng",
                                     @"postalCode",@"state"]];

//[venueMapping addPropertyMapping:[RKRelationshipMapping relationshipMappingFromKeyPath:@"location" toKeyPath:@"location" withMapping:locationMapping]];
[venueMapping addRelationshipMappingWithSourceKeyPath:@"response.venues.location" mapping:locationMapping];


RKResponseDescriptor *responseDescriptor = [RKResponseDescriptor
                                            responseDescriptorWithMapping:venueMapping
                                            pathPattern:nil
                                            keyPath:@"response.venues"
                                            statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];

[objectManager addResponseDescriptor:responseDescriptor];

我的CoreData模型：

enter image description here

每次我运行应用程序时，它始终无法对相同的密钥进行编码。它能够加载场地并将键映射到Venue实体。我相信我处理Venue和Location实体之间关系的方式可能存在问题。

以下是我得到的JSON：

{
  "meta" : {
    "code" : 200
  },
  "response" : {
    "venues" : [
      {
        "id" : "40bbc700f964a520b1001fe3",
        "categories" : [
          {
            "pluralName" : "Plazas",
            "primary" : true,
            "shortName" : "Plaza",
            "id" : "4bf58dd8d48988d164941735",
            "name" : "Plaza",
            "icon" : {
              "prefix" : "https://foursquare.com/img/categories_v2/parks_outdoors/plaza_",
              "suffix" : ".png"
            }
          }
        ],
        "stats" : {
          "checkinsCount" : 75856,
          "usersCount" : 40342,
          "tipCount" : 176
        },
        "venuePage" : {
          "id" : "34303229"
        },
        "storeId" : "",
        "contact" : {
          "phone" : "4157817880",
          "formattedPhone" : "(415) 781-7880",
          "twitter" : "unionsquaresf"
        },
        "hereNow" : {
          "groups" : [],
          "count" : 0
        },
        "verified" : true,
        "url" : "http://visitunionsquaresf.com",
        "referralId" : "v-1373553758",
        "restricted" : true,
        "location" : {
          "address" : "Union Square Park",
          "city" : "San Francisco",
          "distance" : 68,
          "postalCode" : "94108",
          "crossStreet" : "btwn Post, Stockton, Geary & Powell St.",
          "country" : "United States",
          "lat" : 37.787750172585,
          "lng" : -122.40762822536455,
          "state" : "CA",
          "cc" : "US"
        },
        "canonicalUrl" : "https://foursquare.com/v/union-square/40bbc700f964a520b1001fe3",
        "specials" : {
          "count" : 0,
          "items" : []
        },

Answer 1

所以这就是我所知道的：Restkit，出于某种奇怪的原因，正在寻找实体“场地”中的关键“距离”

“distance”不是从Foursquare收到的JSON中的属性，也不是通过代码显式映射的。

我通过将“距离”键添加到“场所”实体来临时修复了直接问题。我不知道它为什么会起作用，以后可能会有一些奇怪的含义。

如果有人能够更多地了解这个问题，我会很高兴地感激它。希望我在代码中做错了，我只是看不到它！

编辑：即使有布莱克的建议，我也遇到了同样的错误。

Answer 2

我认为你的响应描述符和关系映射关键路径都被扭曲了。您是双重指定描述符中的response.venues键路径，然后再次在自引用关系映射中指定。试试这个：

RKEntityMapping *venueMapping = [RKEntityMapping mappingForEntityForName:@"Venue" inManagedObjectStore:managedObjectStore];
RKEntityMapping *locationMapping = [RKEntityMapping mappingForEntityForName:@"Location" inManagedObjectStore:managedObjectStore];

[venueMapping addAttributeMappingsFromDictionary:@{
 @"name":         @"name",
 @"id":           @"venueID",
 @"canonicalUrl": @"canonicalUrl"}];
venueMapping.identificationAttributes = @[@"venueID"];

[locationMapping addAttributeMappingsFromArray:@[ @"address",@"cc",@"city",@"country",@"crossStreet",@"distance",@"lat",@"lng",
                                     @"postalCode",@"state"]];
[venueMapping addRelationshipMappingWithSourceKeyPath:@"location" mapping:locationMapping];


RKResponseDescriptor *responseDescriptor = [RKResponseDescriptor
                                            responseDescriptorWithMapping:venueMapping
                                            pathPattern:nil
                                            keyPath:@"response.venues"
                                            statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];

[objectManager addResponseDescriptor:responseDescriptor];

使用日志记录或单元测试可以更轻松地调试映射。

CoreData严重应用程序错误：实体不符合键值编码

2 个答案: