ios - 关系映射 Restkit

Question

我有两个表，分别是文章和作者。每篇文章有多个作者，同一作者可以出现在多篇文章中。我的 Json 响应如下所示。

{
    "Articles": [
        {
            "artName": "ABC",
            "artId": "1",
            "Authors": [
                {
                    "autName": "James",
                    "autId": "200",
                    "email": "james@xyz.com"
                },
                {
                    "autName": "Mark",
                    "autId": "201",
                    "email": "mark@xyz.com"
                },
                {
                    "autName": "Robert",
                    "autId": "202",
                    "email": "robert@xyz.com"
                }
            ]
        },
        {
            "artName": "BCD",
            "artId": "2",
            "Authors": [
                {
                    "autName": "James",
                    "autId": "200",
                    "email": "james@xyz.com"
                },
                {
                    "autName": "Ben",
                    "autId": "204",
                    "email": "ben@xyz.com"
                },
                {
                    "autName": "Rayon",
                    "autId": "205",
                    "email": "rayon@xyz.com"
                }
            ]
        }
    ]
}

映射:

 RKObjectManager *manager = [[RestKit sharedDataManager] objectManager];
    RKEntityMapping *ArticleMapping = [RKEntityMapping mappingForEntityForName:@"Articles" inManagedObjectStore:manager.managedObjectStore];
    ArticleMaping.identificationAttributes = @[@"artId"];
   ArticleMaping addAttributeMappingsFromDictionary:@{
     @"artId": @"artId",
  }];


  RKEntityMapping *AuthorMapping = [RKEntityMapping mappingForEntityForName:@"Authors" inManagedObjectStore:manager.managedObjectStore];
    AuthorMapping.identificationAttributes = @[@"autId"];

AuthorMapping addAttributeMappingsFromDictionary:@{
     @"autId": @"autId",
@"autName" : @"autName",
@"email" : @"email"

  }];


[ArticleMapping addPropertyMapping:[RKRelationshipMapping relationshipMappingFromKeyPath:@"Authors" toKeyPath:@"Authors" withMapping:AuthorMapping]];

我已经建立了文章和作者的关系。它映射正确，但是当我尝试获取“artName”ABC 的作者时。我只有 2 位作者。但是当我尝试获取“artName”BCD 的数据时。我有 3 位作者。当在数据库中检查时，记录“James”的关系键被 BCD 记录覆盖。

我如何访问这两篇文章的所有作者。

注意:我使用的是 Restkit 0.20

谢谢

Answer 1

两个对象之间的关系需要是多对多的，否则新的赋值将显式地破坏旧的赋值。

当您创建 RKRelationshipMapping 时，请确保将 assignmentPolicy 设置为 RKUnionAssignmentPolicy。默认值为 RKSetAssignmentPolicy，它可能会删除现有设置。