Question

我正在构建一个从网址中提取JSON并使用Core Data和Magical Record将其存储在设备上的应用程序。正在创建数据库，但关系在数据库中显示为null。我试图让它流动的方式是：

用户有连接
连接有类别
这些类别的文章应该从标题中调用基本主题。

下面是我的数据模型，这一部分的一切似乎都很好。

Data Model

这就是我解析数据并将其存储在实体

[_operationManager POST:@"feeds" parameters:parameters success:^(AFHTTPRequestOperation *operation, id responseObject) {

      id connections = [[operation.responseObject objectForKey:@"Data"]objectForKey:@"connections"];

       username.sessionKey =[[operation.responseObject objectForKey:@"Data"]objectForKey:@"sessionId"];

      id connection;
      for(connection in connections){

          //Get the JSON values
          NSString *contentSystemID = [connection objectForKey:@"contentSystemId"];
          NSString *contentSystemName = [connection objectForKey:@"name"];
          NSString *logoUrl =  [connection objectForKey:@"logo"];
          NSNumber *unreadCount = [connection objectForKey:@"unread_count"];


          NSLog(@"Content System ID = %@",contentSystemID);
          NSLog(@"Content System Name = %@",contentSystemName);
          NSLog(@"Logo URL = %@",logoUrl);
          NSLog(@"Unread Count = %@",unreadCount);


          FCConnection *connectionEntity = [FCConnection MR_createEntity];
          connectionEntity.contentSystemID   = contentSystemID;
          connectionEntity.contentSystemName = contentSystemName;
          connectionEntity.logoUrl = logoUrl;
          connectionEntity.unreadCount = unreadCount;

          id categories = [connection objectForKey:@"categories"];
          for (id cat in categories)
          {
             NSString *title = [cat valueForKey:@"name"];
             NSString *unreadCount = [cat valueForKey:@"unread_count"];
             NSLog(@"title  = %@",title);
             NSLog(@"unread_count  = %@",unreadCount);

              id items = [cat objectForKey:@"items"];
             // NSLog(@"items = %@",items);
              for (id item in items){
                  //
                 // NSLog(@"items = %@",item);
                  NSNumber *isRead = [item valueForKey:@"unread"];
                  NSString *title = [item valueForKey:@"title"];
                  NSString *link = [item valueForKey:@"link"];
                  NSString *systemID = [item valueForKey:@"itemId"];

                  NSLog(@"isRead  = %@",isRead);
                  NSLog(@"title  = %@",title);
                  NSLog(@"link  = %@",link);
                  NSLog(@"systemID  = %@",systemID);

                  BaseTopic *baseEntity = [BaseTopic MR_createEntity];
                  baseEntity.title   = title;

                  Article *article = [Article MR_createEntity];
                  article.link = link;
                  article.systemID = systemID;
                  article.isRead = isRead;

              }

          }
      }

          [MagicalRecord saveUsingCurrentThreadContextWithBlock:nil completion:^(BOOL success, NSError *error) {
              NSLog(@"Data Stored");

 }];
       } failure:^(AFHTTPRequestOperation *operation, NSError *error) {

        //Failure
        NSLog(@"Failed to fetch!");

                                         } ];
      }

我知道本节中的某些内容导致我的Core Data文件如下所示。如您所见，数据正在分离并具有多行。应该只有三行，我猜是因为标题是在父实体“BasicTopic”中发生了这个问题。

Duplication and seperation issue

我的下一个问题是关系没有在表格中填充。以下是FCConnection中与用户有关系的行，由于某些奇怪的原因，该行没有填充用户的pk。

任何帮助或建议将不胜感激。

Relationships issue

Answer 1

我没有看到您在数据导入代码中实际进行对象连接的位置。你应该有像

这样的东西

[user addConnectionObject:connection]

在每个循环结束时，以及您需要创建的每个关系

Answer 2

您需要将实体记录映射到每个关系。如果为这些实体生成托管对象子类，则可以看到每种关系的几种方法。你需要使用它来映射实体记录。

id connection;
for(connection in connections)
{
    //Get the JSON values
    NSString *contentSystemID = [connection objectForKey:@"contentSystemId"];
    NSString *contentSystemName = [connection objectForKey:@"name"];
    NSString *logoUrl =  [connection objectForKey:@"logo"];
    NSNumber *unreadCount = [connection objectForKey:@"unread_count"];

    FCConnection *connectionEntity = [FCConnection MR_createEntity];
    connectionEntity.contentSystemID   = contentSystemID;
    connectionEntity.contentSystemName = contentSystemName;
    connectionEntity.logoUrl = logoUrl;
    connectionEntity.unreadCount = unreadCount;

    id categories = [connection objectForKey:@"categories"];

    NSMutableArray *categoryArray = [NSMutableArray array];

    for (id cat in categories)
    {
        NSString *title = [cat valueForKey:@"name"];
        NSString *unreadCount = [cat valueForKey:@"unread_count"];

        id items = [cat objectForKey:@"items"];

        BaseTopic *baseEntity = [BaseTopic MR_createEntity];
        baseEntity.title   = title;

FCCatgory *category = [FCCatgory MR_createEntity];

        NSMutableArray *itemArray = [NSMutableArray array];

        for (id item in items)
        {
            NSNumber *isRead = [item valueForKey:@"unread"];
            NSString *title = [item valueForKey:@"title"];
            NSString *link = [item valueForKey:@"link"];
            NSString *systemID = [item valueForKey:@"itemId"];

            Article *article = [Article MR_createEntity];
            article.link = link;
            article.systemID = systemID;
            article.isRead = isRead;

            article.category = category;

            [itemArray addObject:article];
        }

        [category addArticles:[NSSet setWithArray:itemArray]]; // mapping the items to category
        category.connection = connectionEntity;
        [categoryArray addObject:category];
    }

    [connectionEntity addCategories:[NSSet setWithArray:categoryArray]]; // mapping the items to connection entity
}

希望这会对你有所帮助

核心数据未正确存储

2 个答案: