ios - 魔法记录不保存

Question

我正在使用 Magical Record: https://github.com/magicalpanda/MagicalRecord

我正在尝试使用 Magical Record 和 Core Data 将从我的网站获取的记录保存到 sqllite 数据库，但我不断收到错误消息:

MR_saveWithErrorCallback:](0xaaa6bd0) NO CHANGES IN CONTEXT <NSManagedObjectContext (0xaaa6bd0): *** BACKGROUND SAVING (ROOT) ***> on *** BACKGROUND THREAD *** - NOT SAVING

代码如下:

             for(int i = 0; i < count; i += 1)
             {
                 // results  = array of all services from site
                 NSDictionary * result = [results objectAtIndex: i];

                 NSNumber * sid = @([[result objectForKey: @"id"] intValue]);
                 NSNumber * parent = @([[result objectForKey: @"parent"] intValue]);
                 Service * service  = [Service createEntity];

                 NSString * image = [NSString stringWithFormat: @"%@", [result objectForKey: @"image"]];

                 NSString * name  = [NSString stringWithFormat: @"%@", [result objectForKey: @"name"]];
                 NSString * machine_name  = [NSString stringWithFormat: @"%@", [result objectForKey: @"machine_name"]];


                 [service setDate: [NSDate date]];
                 [service setSid: sid];
                 [service setName: name];

                 [service setImage: image];
                 [service setParent: parent];
                 [service setMachine_name: machine_name];


                 [[NSManagedObjectContext defaultContext] saveNestedContexts];

Answer 1

问题是您没有保存正确的上下文。如果您查看源代码，[Service createEntity] 在当前线程的上下文中创建 ManagedObject。不在 defaultContext 中。

所以您需要做的是，您应该保存当前线程的上下文(即创建 ManagedObject 的上下文)，而不是 [[NSManagedObjectContext defaultContext] saveNestedContexts]。所以代码应该是[[NSManagedObjectContext MR_contextForCurrentThread]