Question

我有一个RKEntitiyMapping对象，用于映射与子项具有一对一关系的对象。

调用以下代码时：

[sessionMapping addConnectionForRelationship:@"dailyGoalDetail" connectedBy:@{ @"dailyGoalDetailId": @"dailyGoalDetailId" }];

通过addConnectionForRelationship方法进行调试，我发现添加到连接集合的连接是nil。我通过这种方式找到与Core Data的连接进行了双重检查：

NSEntityDescription *parentEntity = [NSEntityDescription entityForName:@"Session" inManagedObjectContext:[MGRModel sharedModel].managedObjectStore.persistentStoreManagedObjectContext]; NSRelationshipDescription *childRelationship = [parentEntity relationshipsByName][@"dailyGoalDetail"]; [sessionMapping addConnectionForRelationship:childRelationship connectedBy:@{@"dailyGoalDetailId":@"dailyGoalDetailId"}];

登录到控制台我的关系显示它。但是addConnectionForRelationship方法仍然会为其集合添加一个nil连接。

这有什么问题？

更新

这是我的Session对象的相关代码：

+ (RKEntityMapping *)responseMapping
{
    RKEntityMapping* sessionMapping = [RKEntityMapping mappingForEntityForName:@"Session" inManagedObjectStore:[[MGRModel sharedModel] managedObjectStore]];
    [sessionMapping addAttributeMappingsFromDictionary:@{
                                                         @"ActivityId": @"activityType",
                                                         @"DailyGoalDetailId": @"dailyGoalDetailId",
                                                         @"DeviceGuid": @"deviceId",
                                                         @"DeviceSessionId": @"entityId",
                                                         @"Frequency": @"frequency",
                                                         @"Pace": @"pace",
                                                         @"Start": @"start",
                                                         @"Stop": @"stop",
                                                         @"TotalBeats": @"totalBeats",
                                                         @"TotalKcal": @"totalCalories",
                                                         }];
    sessionMapping.identificationAttributes = @[ @"entityId" ];

    // Add relationship mapping with Measurement as "sessionDetails"
    [sessionMapping addPropertyMapping:[RKRelationshipMapping relationshipMappingFromKeyPath:@"SessionDetails"
                                                                                   toKeyPath:@"sessionDetails"
                                                                                 withMapping:[MGRMeasurement responseMapping]]];

    NSEntityDescription *parentEntity = [NSEntityDescription entityForName:@"Session" inManagedObjectContext:[MGRModel sharedModel].managedObjectStore.persistentStoreManagedObjectContext];
    NSRelationshipDescription *childRelationship = [parentEntity relationshipsByName][@"dailyGoalDetail"];
    [sessionMapping addConnectionForRelationship:childRelationship connectedBy:@{@"dailyGoalDetailId":@"dailyGoalDetailId"}];

//    [sessionMapping addConnectionForRelationship:@"dailyGoalDetail" connectedBy:@{ @"dailyGoalDetailId": @"dailyGoalDetailId" }];

    return sessionMapping;
}

这是关系中的一个方面：

(lldb) po childRelationship
(<NSRelationshipDescription: 0xc266570>), name dailyGoalDetail, isOptional 1, isTransient 0, entity Session, renamingIdentifier dailyGoalDetail, validation predicates (
), warnings (
), versionHashModifier (null)
 userInfo {
}, destination entity DailyGoalDetail, inverseRelationship sessions, minCount 0, maxCount 1, isOrdered 0, deleteRule 1

更多信息。 JSON是这样的：

{
  "DailyGoalDetails": [
    {
      "DailyGoal": {
        "ActivityUnit": {
          "ActivityUnitId": 1,
          "Name": "BEATS"
        },
        "DailyGoalId": 1,
        "ActivityUnitId": 1,
        "Name": "Un inizio facile",
        "Beats": 25,
        "Level": 1
      },
      "DailyGoalDetailId": 6,
      "DailyGoalId": 1,
      "UserId": "7a2e5b7c-9a3a-4ad1-ad79-946bcf2bf2f3",
      "Hit": true,
      "Value": 9,
      "GoalDate": "2014-04-16T00:00:00",
      "AvgActivityTime": 12
    }
  ],
  "UserSessions": [
    {
      "UserSessionId": 0,
      "DeviceGuid": "962d26a01cdef0c8",
      "DeviceSessionId": "2a0bb7a0-041d-4df6-abcb-e50483858cba",
      "DailyGoalId": 1,
      "DailyGoalDetailId": 6,
      "ActivityId": 1,
      "Start": "2014-04-16T16:10:11",
      "Stop": "2014-04-16T16:15:53",
      "TotalBeats": 0,
      "TotalKcal": 1,
      "Pace": 0.00,
      "Frequency": 1,
      "SessionDetails": [
        {
          "Speed": 0.0,
          "Step": 4,
          "Distance": 0.0,
          "Beats": 0.0033395835198462009,
          "Lat": 45.70608193,
          "Lng": 9.70917967,
          "Altitude": 298.0,
          "Orientation": 0.0,
          "Start": "2014-04-16T16:10:10",
          "Stop": "2014-04-16T16:10:11"
        },
        {
          "Speed": 0.0,
          "Step": 2,
          "Distance": 0.0,
          "Beats": 0.0033395835198462009,
          "Lat": 45.70608193,
          "Lng": 9.70917967,
          "Altitude": 298.0,
          "Orientation": 0.0,
          "Start": "2014-04-16T16:10:11",
          "Stop": "2014-04-16T16:10:12"
        },
      ]
    }
  ]
}

初始化并调用mapper的相关代码（这是通过NSString完成的）：

        // Json decoding
        NSError *decodingError = nil;
        id parsedData = [RKMIMETypeSerialization objectFromData:decodedUncompressedData MIMEType:RKMIMETypeJSON error:&decodingError];
        if (parsedData == nil && error) {
            NSLog(@"Error decoding json received from synchronization");
        }
        NSMutableDictionary *mappingsDictionary = [[NSMutableDictionary alloc] init];
        // Add DailyGoalDetails->MGRDailyGoalDetail mapping
        [mappingsDictionary setObject:[MGRDailyGoalDetail responseMapping] forKey:@"DailyGoalDetails"];
        // Add UserSessions->MGRSession mapping
        [mappingsDictionary setObject:[MGRSession responseMapping] forKey:@"UserSessions"];
        RKMapperOperation *mapper = [[RKMapperOperation alloc] initWithRepresentation:parsedData mappingsDictionary:mappingsDictionary];
        RKManagedObjectMappingOperationDataSource *dataSource = [[RKManagedObjectMappingOperationDataSource alloc] initWithManagedObjectContext:[MGRModel sharedModel].managedObjectStore.persistentStoreManagedObjectContext cache:[MGRModel sharedModel].managedObjectStore.managedObjectCache];
        dataSource.parentOperation = mapper;
        mapper.mappingOperationDataSource = dataSource;
        NSError *mappingError = nil;
        BOOL isMapped = [mapper execute:&mappingError];
        if (isMapped && !mappingError) {
            NSLog(@"jsonMappingResult = %@",[mapper mappingResult]);
            [[[[MGRModel sharedModel] managedObjectStore] persistentStoreManagedObjectContext] save:&mappingError];
        }

Answer 1

RKMapperOperation实际上并没有做太多工作。在内部，它使用RKMappingOperation，这就是连接的原因。为了使它工作，你有两个选择：

使用彼此依赖的2个RKMapperOperation个实例，会话映射器运行第二个
使用RKObjectManager监督整个过程

如果您直接使用mapper操作，那么您将需要其中两个，以便您可以明确控制订单。从理论上讲，您也可以将连接添加到两个映射中，因此首先运行哪个并不重要（只要它们都由相同的MOC支持）。

RestKit addConnectionForRelationship无法识别连接

1 个答案: