魔法记录没有保存

Question

我正在使用魔法记录:https: //github.com/magicalpanda/MagicalRecord

我试图使用魔法记录和核心数据保存从我的网站到sqllite数据库的记录,但我一直收到错误:

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

这是代码:

             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.如果查看源代码,请[Service createEntity]在当前线程的上下文中创建ManagedObject.不在defaultContext中.

所以你需要做的是,[[NSManagedObjectContext defaultContext] saveNestedContexts]你应该保存当前线程的上下文(即创建ManagedObject的上下文).所以代码应该是[[NSManagedObjectContext MR_contextForCurrentThread]

Answer 2

您是否尝试过使用saveInBackgroundWithBlock:实用程序方法？

如果没有,你可能想尝试类似下面的代码.请注意,它将在后台一次性保存所有对象,然后在主线程上执行完成块:

[MagicalRecord saveInBackgroundWithBlock:^(NSManagedObjectContext *localContext){
    Service *service = [Service createInContext:localContext];

    ... set values ...
} completion:^{
    ...
}];

除此之外,您可以查看是否[[NSManagedObjectContext defaultContext] hasChanges]返回YES以检查是否存在保存或实体本身的问题.