使用RestKit映射嵌套的CoreData对象会导致验证错误

Question

我曾经多次使用RestKit进行对象映射，但这是第一次使用核心数据对象。

我将嵌套的json内容映射到两个核心数据实体。这会导致验证错误 - 映射失败。

为什么关系失败的任何建议？

 E restkit.object_mapping:RKMappingOperation.m:335 Validation failed while mapping attribute at key path 'workflowSteps' to value {(
<NUWorkflowStepMO: 0xe717a00> (entity: WorkflowSteps; id: 0xe717a40 <x-coredata:///WorkflowSteps/t150ED0DB-CADD-46FD-804F-1F2094B7C7DF194> ; data: {
operatingCompany = nil;
"operatingCompany_id" = 475;
position = 2;
step = SecurityCheck;
uid = 222;
}),
<NUWorkflowStepMO: 0xe88c1a0> (entity: WorkflowSteps; id: 0xe8e5a50 <x-coredata:///WorkflowSteps/t150ED0DB-CADD-46FD-804F-1F2094B7C7DF195> ; data: {
operatingCompany = nil;
"operatingCompany_id" = 475;
position = 3;
step = "Mission Complete";
uid = 333;
}),
<NUWorkflowStepMO: 0xe7194b0> (entity: WorkflowSteps; id: 0xe7194a0 <x-coredata:///WorkflowSteps/t150ED0DB-CADD-46FD-804F-1F2094B7C7DF193> ; data: {
operatingCompany = nil;
"operatingCompany_id" = 475;
position = 1;
step = Welcome;
uid = 111;
})
)}. Error: The operation couldn’t be completed. (Cocoa error 1550.)
2014-07-24 14:39:23.868 NuBON-Dev[43457:60b] E restkit:RKLog.m:151 Validation Error
                    NSLocalizedDescriptionKey:      The operation couldn’t be completed. (Cocoa error 1550.)
                    NSValidationKeyErrorKey:            workflowSteps
                    NSValidationPredicateErrorKey:  (null)
                    NSValidationObjectErrorKey:
<NUOperatingCompanyMO: 0xe9c3be0> (entity: OperatingCompany; id: 0xe9c3c20 <x- coredata:///OperatingCompany/t150ED0DB-CADD-46FD-804F-1F2094B7C7DF192> ; data: {
categoryId = 0;
workflowSteps =     (
);
uid = 475;
})

这是json：

{
"operatingCompanyIds":[
                       475
                       ],
"itemCount":1,
"items":[
         {
         "id":475,
         "workflowStep":[
                                 {
                                 "id":111,
                                 "operatingCompany_id":475,
                                 "step":"Welcome",
                                 "position":1
                                 },
                                 {
                                 "id":222,
                                 "operatingCompany_id":475,
                                 "step":"SecurityCheck",
                                 "position":2
                                 },
                                 {
                                 "id":333,
                                 "operatingCompany_id":475,
                                 "step":"Mission Complete",
                                 "position":3
                                 }
                                 ],
         "categoryId":3,
         }
         ]
}

我有两个实体的核心数据模型＆＃34; item＆＃34;和＆＃34; workflowStep＆＃34;，item与workflowSteps有多对多的关系。

这是我的映射：

OperatingCompany：

+ (NSDictionary*) mappingDictionary {
return @{
         @"id": @"uid",
         @"name": @"name",
         @"category_id": @"category_id",
         };
}

 + (RKEntityMapping*) entityMappingForManagedObjectStore:(RKManagedObjectStore *)managedObjectStore {
RKEntityMapping* mapping = [RKEntityMapping mappingForEntityForName:[NUOperatingCompanyMO entityName] inManagedObjectStore:managedObjectStore];
[mapping setIdentificationAttributes:@[@"uid"]];
[mapping addAttributeMappingsFromDictionary:[NUOperatingCompanyMO mappingDictionary]];

RKRelationshipMapping* relationshipMapping = [RKRelationshipMapping relationshipMappingFromKeyPath:@"workflowStep" toKeyPath:@"workflowSteps" withMapping:[NUCheckoutWorkStepMO entityMappingForManagedObjectStore:managedObjectStore]];
[mapping addPropertyMapping:relationshipMapping];
}

WorkflowStep

+ (NSDictionary*) mappingDictionary {
return @{
         @"id": @"uid",
         @"operatingCompany_id": @"operatingCompany_id",
         @"step": @"step",
         @"position": @"position"
         };
}

+ (RKEntityMapping*) entityMappingForManagedObjectStore:(RKManagedObjectStore *)managedObjectStore {
RKEntityMapping* mapping = [RKEntityMapping mappingForEntityForName:[NUCheckoutWorkStepMO entityName] inManagedObjectStore:managedObjectStore];
[mapping setIdentificationAttributes:@[@"uid"]];
[mapping addAttributeMappingsFromDictionary:[NUCheckoutWorkStepMO mappingDictionary]];

[mapping addConnectionForRelationship:@"operatingCompany" connectedBy:@"uid"];

return mapping;
}