Question

我有一个名为Core Data的实体（位于Contact上），每个联系人都有一个Neighborhood，User和ContactOrigin个实体。当我从服务器中检索JSON数据时，我得到这样的结果：

{
  "contact" : [
    {
      "prospect" : {
        "pkProspect" : 21,
        "name" : "Test Contact",
        "email" : "test@domain.com",
        "phone" : "5555555555",
        "address" : "Test Avenue",
        "media" : {
          "pkMedia" : 3,
          "name" : "Referência Entrevista You Move"
        },
        "neighborhood" : {
          "pkNeighborhood" : 15857,
          "name" : "Donwtown"
        }
      },
      "user" : {
        "firstName" : "John",
        "pkPerson" : 5,
        "lastName" : "Doe"
      }
    }
  ]
}

正如您所看到的，我有一个联系人阵列，每个联系人都有一个用户节点，一个邻居节点和一个媒体节点（我在我的数据库中用作原点）。 RestKit似乎正在使用此代码正确映射：

// Getting the object manager.
RKObjectManager *objectManager = [RKObjectManager sharedManager];

// Relationship mappings.    
RKManagedObjectMapping *neighborhoodMapping = [RKManagedObjectMapping mappingForClass:[Neighborhood class] inManagedObjectStore:objectManager.objectStore];
neighborhoodMapping.primaryKeyAttribute = @"identifier";
[neighborhoodMapping mapKeyPath:@"pkNeighborhood" toAttribute:@"identifier"];

RKManagedObjectMapping *originMapping = [RKManagedObjectMapping mappingForClass:[ContactOrigin class] inManagedObjectStore:objectManager.objectStore];
originMapping.primaryKeyAttribute = @"identifier";
[originMapping mapKeyPath:@"pkMedia" toAttribute:@"identifier"];

RKManagedObjectMapping *userMapping = [RKManagedObjectMapping mappingForClass:[User class] inManagedObjectStore:objectManager.objectStore];
userMapping.primaryKeyAttribute = @"identifier";
[userMapping mapKeyPath:@"pkPerson" toAttribute:@"identifier"];

// Creating the contact mapping for the request.
RKManagedObjectMapping *contactMapping = [RKManagedObjectMapping mappingForClass:[Contact class] inManagedObjectStore:objectManager.objectStore];
contactMapping.primaryKeyAttribute = kContactFieldNameId;

[contactMapping mapKeyPath:@"prospect.neighborhood" toRelationship:@"addressNeighborhood" withMapping:neighborhoodMapping];
[contactMapping mapKeyPath:@"prospect.media" toRelationship:@"origin" withMapping:originMapping];
[contactMapping mapKeyPath:@"user" toRelationship:@"user" withMapping:userMapping];

[contactMapping connectRelationship:@"addressNeighborhood" withObjectForPrimaryKeyAttribute:@"identifier"];
[contactMapping connectRelationship:@"origin" withObjectForPrimaryKeyAttribute:@"identifier"];
[contactMapping connectRelationship:@"user" withObjectForPrimaryKeyAttribute:@"identifier"];

[contactMapping mapKeyPath:@"prospect.pkProspect" toAttribute:@"identifier"];
[contactMapping mapKeyPath:@"prospect.name" toAttribute:@"name"];
[contactMapping mapKeyPath:@"prospect.email" toAttribute:@"email"];
[contactMapping mapKeyPath:@"prospect.phone" toAttribute:@"phone"];
[contactMapping mapKeyPath:@"prospect.address" toAttribute:@"address"];

// Setting the result mapping.
[objectManager.mappingProvider setObjectMapping:contactMapping forKeyPath:@"contact"];
// Loading data.
[objectManager loadObjectsAtResourcePath:resourcePath usingBlock:^(RKObjectLoader *loader) {
    loader.delegate = self;
    loader.userData = delegate;
}];

映射完成后，我收到以下消息（我只显示User错误）：

2012-07-06 18:20:23.016 Contact Manager[8254:10c03] E restkit.core_data:RKManagedObjectStore.m:250 Core Data Save Error
                               NSLocalizedDescription:      The operation couldn’t be completed. (Cocoa error 1570.)
                               NSValidationErrorKey:            user
                               NSValidationErrorPredicate:  (null)
                               NSValidationErrorObject:
<Contact: 0x917dff0> (entity: Contact; id: 0x917e070 <x-coredata:///Contact/t9D9EE4AE-142A-45EC-88C1-E97833729D0C2> ; data: {
    address = "Test Avenue";
    addressNeighborhood = "0x918b5b0 <x-coredata://6E5AB6F3-AFF4-460E-A37D-285A105178F0/Neighborhood/p21>";
    email = "test@domain.com";
    identifier = 21;
    name = "Test Contact";
    origin = nil;
    phone = 5555555555;
    user = nil;
})
2012-07-06 18:20:23.024 Contact Manager[8254:10c03] E restkit.core_data:RKManagedObjectLoader.m:167 Failed to save managed object context after mapping completed: The operation couldn’t be completed. (Cocoa error 1560.)

正如您所看到的，origin和user都为空，当我尝试将其保存在Core Data时会导致错误，因为这些字段是必需的，但如果我们采取看一下RestKit中的日志，我们会看到这些对象已被正确解析，实际上它们存在于数据库中。

2012-07-06 18:20:22.938 Contact Manager[8254:10c03] D restkit.object_mapping:RKObjectMappingOperation.m:636 Starting mapping operation...
2012-07-06 18:20:22.940 Contact Manager[8254:10c03] T restkit.object_mapping:RKObjectMappingOperation.m:637 Performing mapping operation: RKObjectMappingOperation for 'User' object. Mapping values from object {
    firstName = John;
    lastName = Doe;
    pkPerson = 5;
} to object <User: 0x5ca9d60> (entity: User; id: 0xc5aa7a0 <x-coredata://6E5AB6F3-AFF4-460E-A37D-285A105178F0/User/p1> ; data: {
    contacts = "<relationship fault: 0xc5ab580 'contacts'>";
    email = "john@domain.com";
    identifier = 5;
    ip = "0.0.0.0";
    isLoggedIn = 1;
    language = "en";
    name = "John Doe";
    password = 4badaee57fed5610012a296273158f5f;
}) with object mapping <RKManagedObjectMapping:0x5ca78b0 objectClass=User keyPath mappings => (
    "RKObjectKeyPathMapping: pkPerson => identifier"
)>
2012-07-06 18:20:22.942 Contact Manager[8254:10c03] T restkit.object_mapping:RKObjectMappingOperation.m:330 Mapping attribute value keyPath 'pkPerson' to 'identifier'
2012-07-06 18:20:22.943 Contact Manager[8254:10c03] D restkit.object_mapping:RKObjectPropertyInspector.m:107 Cached property names and types for Class 'User': {
    accessibilityHint = NSString;
    accessibilityLabel = NSString;
    accessibilityLanguage = NSString;
    accessibilityValue = NSString;
    contacts = NSSet;
    email = NSString;
    identifier = NSNumber;
    ip = NSString;
    isLoggedIn = NSNumber;
    language = NSString;
    name = NSString;
    password = NSString;
}
2012-07-06 18:20:22.944 Contact Manager[8254:10c03] T restkit.object_mapping:RKObjectMappingOperation.m:347 Skipped mapping of attribute value from keyPath 'pkPerson to keyPath 'identifier' -- value is unchanged (5)
2012-07-06 18:20:22.946 Contact Manager[8254:10c03] D restkit.object_mapping:RKObjectMappingOperation.m:643 Finished mapping operation successfully...
2012-07-06 18:20:22.966 Contact Manager[8254:10c03] T restkit.object_mapping:RKObjectMappingOperation.m:597 Mapped relationship object from keyPath 'user' to 'user'. Value: <User: 0x5ca9d60> (entity: User; id: 0xc5aa7a0 <x-coredata://6E5AB6F3-AFF4-460E-A37D-285A105178F0/User/p1> ; data: {
    contacts = "<relationship fault: 0xc5ab580 'contacts'>";
    email = "john@domain.com";
    identifier = 5;
    ip = "0.0.0.0";
    isLoggedIn = 1;
    language = "pt_BR";
    name = "John Doe";
    password = 4badaee57fed5610012a296273158f5f;
})
2012-07-06 18:20:22.968 Contact Manager[8254:10c03] D restkit.object_mapping:RKObjectMappingOperation.m:643 Finished mapping operation successfully...

所以，我的问题是，如果解析器将这些对象发现到数据库中，user和origin为空？映射有什么问题吗？

Answer 1

经过大量调试后，我找到了解决问题的方法。首先，我为每个对象使用相同的主键（@"identifier"）这一事实搞乱了映射。

之后，我删除了[contactMapping connectRelationship:withObjectForPrimaryKeyAttribute:]，因为它不需要，现在一切似乎都有效。

Restkit对象映射给出了null对象

1 个答案: