Question

请指导我以下问题。

我有两个关系实体，如下图所示 enter image description here

我正在使用最新版本的RestKit和iOS 7

现在在我的appDelegate中，我正在使用“List”实体的以下映射

    NSDictionary *listObjectMapping = @{
                                      @"listID" : @"listID",
                                      @"listName" : @"listName",
                                      @"listSyncStatus" : @"listSyncStatus"
                              };

RKEntityMapping *listEntityMapping = [RKEntityMapping mappingForEntityForName:@"List" inManagedObjectStore:managedObjectStore];
[listEntityMapping addAttributeMappingsFromDictionary:listObjectMapping];

listEntityMapping.identificationAttributes = @[ @"listID" ];

RKResponseDescriptor *responseDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:listEntityMapping
                                                                                        method:RKRequestMethodGET
                                                                                   pathPattern:@"/api/lists"
                                                                                       keyPath:nil
                                                                                   statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];
[objectManager addResponseDescriptor:responseDescriptor];


//Inverse mapping, to perform a POST
RKRequestDescriptor *requestDescriptor = [RKRequestDescriptor requestDescriptorWithMapping:[listEntityMapping inverseMapping]
                                                                               objectClass:[List class]
                                                                               rootKeyPath:nil
                                                                                    method:RKRequestMethodPOST];
objectManager.requestSerializationMIMEType = RKMIMETypeJSON;
[objectManager setAcceptHeaderWithMIMEType:RKMIMETypeJSON];

[RKMIMETypeSerialization registerClass:[RKNSJSONSerialization class] forMIMEType:@"application/json"];
[objectManager addRequestDescriptor:requestDescriptor];



//Inverse mapping, to perform a PUT
requestDescriptor = [RKRequestDescriptor requestDescriptorWithMapping:[listEntityMapping inverseMapping]
                                                                               objectClass:[List class]
                                                                               rootKeyPath:nil
                                                                                    method:RKRequestMethodPUT];
objectManager.requestSerializationMIMEType = RKMIMETypeJSON;
[objectManager setAcceptHeaderWithMIMEType:RKMIMETypeJSON];

[RKMIMETypeSerialization registerClass:[RKNSJSONSerialization class] forMIMEType:@"application/json"];
[objectManager addRequestDescriptor:requestDescriptor];

并为我的Task对象使用以下映射

    NSDictionary *taskObjectMapping = @{
                                    @"listID" : @"listID",
                                    @"taskID" : @"taskID",
                                    @"taskName" : @"taskName",
                                    @"taskCompletionStatus" : @"taskCompletionStatus",
                                    @"taskSyncStatus" : @"taskSyncStatus"
                                };

RKEntityMapping *taskEntityMapping = [RKEntityMapping mappingForEntityForName:@"Task" inManagedObjectStore:managedObjectStore];
[taskEntityMapping addAttributeMappingsFromDictionary:taskObjectMapping];
taskEntityMapping.identificationAttributes = @[ @"taskID" ];


RKResponseDescriptor *taskResponseDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:taskEntityMapping
                                                                                            method:RKRequestMethodGET
                                                                                       pathPattern:@"/api/list/:id"
                                                                                           keyPath:nil
                                                                                       statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];
[objectManager addResponseDescriptor:taskResponseDescriptor];


//Inverse mapping, to perform a POST
RKRequestDescriptor *taskRequestDescriptor = [RKRequestDescriptor requestDescriptorWithMapping:[taskEntityMapping inverseMapping]
                                                                               objectClass:[Task class]
                                                                               rootKeyPath:nil
                                                                                    method:RKRequestMethodPOST];
objectManager.requestSerializationMIMEType = RKMIMETypeJSON;
[objectManager setAcceptHeaderWithMIMEType:RKMIMETypeJSON];
[RKMIMETypeSerialization registerClass:[RKNSJSONSerialization class] forMIMEType:@"application/json"];
[objectManager addRequestDescriptor:taskRequestDescriptor];



//Inverse mapping, to perform a PUT
taskRequestDescriptor = [RKRequestDescriptor requestDescriptorWithMapping:[taskEntityMapping inverseMapping]
                                                          objectClass:[Task class]
                                                          rootKeyPath:nil
                                                               method:RKRequestMethodPUT];
objectManager.requestSerializationMIMEType = RKMIMETypeJSON;
[objectManager setAcceptHeaderWithMIMEType:RKMIMETypeJSON];
[RKMIMETypeSerialization registerClass:[RKNSJSONSerialization class] forMIMEType:@"application/json"];
[objectManager addRequestDescriptor:taskRequestDescriptor];

现在我的问题是如何在这两个实体之间添加关系映射？什么是正确的方法？

如果我使用我使用以下代码行

[taskEntityMapping addPropertyMapping:[RKRelationshipMapping relationshipMappingFromKeyPath:@"list.listID"
                                                                                  toKeyPath:@"listID"
                                                                                withMapping:listEntityMapping]];

发生运行时错误，说“无法为keyPath listID添加映射，一个已经存在”

如果我使用这个

[listEntityMapping addPropertyMapping:[RKRelationshipMapping relationshipMappingFromKeyPath:@"listID"
                                                                                      toKeyPath:@"list.listID"
                                                                                    withMapping:taskEntityMapping]];

应用程序因此错误而崩溃实体列表不符合密钥值，符合密钥“list”。

如果我省略上面的代码并尝试从关系中获取listID

task.list.listID

它给了我“0”。任何人都可以告诉我，我到底做错了什么，或者我应该怎样做才能完成上述任务。如果需要，我可以提供更多细节。

修改

但我对所有列表的请求都返回json

GET www.mydomain.com/api/lists

[
{"listID":"42","listName":"List 4","listSyncStatus":"1"},
{"listID":"41","listName":"List 3","listSyncStatus":"1"},
{"listID":"40","listName":"List 2","listSyncStatus":"1"}
]

对单个列表的请求将返回其任务如下

GET www.mydomain.com/api/list/42
[
{"taskID":"22","listID":"42","taskName":"Task 2","taskSyncStatus":"1","taskCompletionStatus":"1"},

{"taskID":"21","listID":"42","taskName":"Task 1","taskSyncStatus":"1","taskCompletionStatus":"1"}
]

即在json中返回没有级联关系。这是错误的方式还是我在这里缺少什么？

接受答案后更正

事实证明我回错了json，即返回的json没有关系，而iOS模型有一个关系“tasks”所以我编辑我的休息api返回正确的嵌套json，如下所示

    [ { "listID" : "96",
    "listName" : "List 1",
    "listSyncStatus" : "1",
    "tasks" : [ { "taskCompletionStatus" : "1",
          "taskID" : "67",
          "taskName" : "Task 2",
          "taskSyncStatus" : "1"
        },
        { "taskCompletionStatus" : "1",
          "taskID" : "66",
          "taskName" : "Task 1",
          "taskSyncStatus" : "1"
        }
      ]
  },
  { "listID" : "97",
    "listName" : "List 2",
    "listSyncStatus" : "1",
    "tasks" : [ { "taskCompletionStatus" : "1",
          "taskID" : "69",
          "taskName" : "Task 1",
          "taskSyncStatus" : "1"
        },
        { "taskCompletionStatus" : "1",
          "taskID" : "68",
          "taskName" : "Task 1",
          "taskSyncStatus" : "1"
        }
      ]
  }
]

返回上面嵌套的json后，一切都像魅力一样，特别是这一行

[listEntityMapping addPropertyMapping:[RKRelationshipMapping relationshipMappingFromKeyPath:@"tasks"
                                                                                  toKeyPath:@"tasks"
                                                                                withMapping:taskEntityMapping]];

希望这有助于为像我这样的人掌握关系概念。

Answer 1

您的模态图显示您具有一对多关系（一个列表包含许多任务）。

据我所知，在这种情况下，您只需要在列表实体上添加关系映射，不需要任务实体。此外，对于一对多关系，您无需在list实体下添加Task关系。

您的实体关系应如下所示

enter image description here

请尝试按照

[listEntityMapping addPropertyMapping:[RKRelationshipMapping relationshipMappingFromKeyPath:@"YOUR_JSON_KEYPATH_HERE" toKeyPath:@"tasks" withMapping: taskEntityMapping]];

重要

以上方法

FromKeyPath parameter应该是关系开始的JSON key的名称。

toKeyPath parameter应该是您在实体图中提到的relationship name。即; tasks。

withMapping应该是许多实体的映射。在您的情况下taskEntityMapping

希望这可以解决问题。

Answer 2

不确定为什么这不起作用，但您可以尝试创建这样的关系映射：

[taskEntityMapping addConnectionForRelationship:@"list" connectedBy:@{ @"listId": @"listId" }];
[listEntityMapping addConnectionForRelationship:@"tasks" connectedBy:@{ @"listId":@"listId"}];

RestKit添加属性映射和关系映射

2 个答案: