iPhone Core Data关系错误(iPhone Core Data relationship fault)
我正在构建核心数据iphone应用程序,并且无法检索一对多的关系数据。 我解释时请耐心等待。
我使用数据模型设计器来设置一个名为“Item”的实体,其中包含许多名为“Comment”的实体。 然后我检索多个实体并在
UITableView
显示它们。 我像这样获取这些实体(在viewDidLoad
方法中):NSFetchRequest *request = [[NSFetchRequest alloc] init]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"Items" inManagedObjectContext:self.managedObjectContext]; [request setEntity:entity]; NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(Item_to_Areas.Name LIKE %@)",[areaManagedObject valueForKey:@"Name"]]; [request setPredicate:predicate]; [request setRelationshipKeyPathsForPrefetching:[NSArray arrayWithObject:@"Item_to_item_comments"]]; NSLog(@"Results: %@", [mutableItemsFetchResults description]); mutableItemsFetchResults = [[managedObjectContext executeFetchRequest:request error:nil] mutableCopy]; [request release];
当用户点击一行时,我选择特定的entiny,在其init方法中将其传递给新的表视图控制器,并将新的视图控制器推送到堆栈:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { NSLog(@"itemObject: %@", [mutableItemsFetchResults objectAtIndex:indexPath.row]); InspectionItemCommentsViewController *itemCommentsViewController = [[InspectionItemCommentsViewController alloc] initWithManagedObjectContext:self.managedObjectContext itemObject:[mutableItemsFetchResults objectAtIndex:indexPath.row]]; itemCommentsViewController.hidesBottomBarWhenPushed = YES; [self.navigationController pushViewController:itemCommentsViewController animated:YES]; [itemCommentsViewController release]; }
在第一个块中,NSLog输出显示检索到“Item_to_item_comments”关系实体,但在第二个块中,即使我调用了[request setRelationshipKeyPathsForPrefetching:[NSArray arrayWithObject:@“Item_to_item_comments”]]。
这是第一个NSLog输出的一部分:
Results: ( "<NSManagedObject: 0xb356b70> (entity: Items; id: 0xb34fe60 <x-coredata://E43A90B5-AF0E- 4394-B4A7-5EFE74E181F8/Items/p1> ; data: {\n Clean = nil;\n Description = \"\";\n ItemToInformation = \"<relationship fault: 0x5e1ef00 'ItemToInformation'>\";\n \"Item_to_Areas\" = \"0xb33fd30 <x-coredata://E43A90B5-AF0E-4394-B4A7-5EFE74E181F8/Areas/p1>\";\n \"Item_to_item_comments\" = \"<relationship fault: 0x5e1d300 'Item_to_item_comments'>\";\n Keys = nil;\n Name = Other;\n \"Tenant_agrees\" = nil;\n Undamaged = nil;\n Working = nil;\n})", "<NSManagedObject: 0xb35a930> (entity: Items; id: 0xb32acc0 <x-coredata://E43A90B5-AF0E-4394-B4A7-5EFE74E181F8/Items/p2> ; data: {\n Clean = nil;\n Description = \"\";\n ItemToInformation = \"<relationship fault: 0x790de40 'ItemToInformation'>\";\n \"Item_to_Areas\" = \"0xb33fd30 <x-coredata://E43A90B5-AF0E-4394-B4A7-5EFE74E181F8/Areas/p1>\";\n \"Item_to_item_comments\" = (\n \"0xb35bcb0 <x-coredata://E43A90B5-AF0E-4394-B4A7-5EFE74E181F8/Item_Comments/p13>\",\n \"0xb35bcd0 <x-coredata://E43A90B5-AF0E-4394-B4A7-5EFE74E181F8/Item_Comments/p37>\",\n \"0xb35bca0 <x-coredata://E43A90B5-AF0E-4394-B4A7-5EFE74E181F8/Item_Comments/p5>\",\n \"0xb35bcc0 <x-coredata://E43A90B5-AF0E-4394-B4A7-5EFE74E181F8/Item_Comments/p26>\"\n );\n Keys = nil;\n Name = Lights;\n \"Tenant_agrees\" = nil;\n Undamaged = nil;\n Working = nil;\n})",
您可以看到提取了Items实体,包括
Item_to_item_comments
。 这是第二个NSLog:itemObject: <NSManagedObject: 0xe20af50> (entity: Items; id: 0xe209fc0 <x- coredata://E43A90B5-AF0E-4394-B4A7-5EFE74E181F8/Items/p2> ; data: { Clean = nil; Description = ""; ItemToInformation = "<relationship fault: 0xe302e40 'ItemToInformation'>"; "Item_to_Areas" = "0xe500b90 <x-coredata://E43A90B5-AF0E-4394-B4A7-5EFE74E181F8/Areas/p1>"; "Item_to_item_comments" = "<relationship fault: 0xe302e60 'Item_to_item_comments'>"; Keys = nil; Name = Lights; "Tenant_agrees" = nil; Undamaged = nil; Working = nil; })
现在,
Item_to_item_comments
是错误的。 类似地,在推送视图控制器中,传递Items实体,但不传递Item_to_item_comments
。我想我错过了一些明显的东西,但经过一天的花费在这个问题上,我无法弄清楚。
任何帮助,将不胜感激。
彼得
I am building a core data iphone app, and having trouble with retrieving one-many relationship data. Please bear with me while I explain.
I have used the data model designer to setup an entity called "Item" that contains many entities called "Comment". I then retrieve multiple entities and display them in a
UITableView
. I fetch these entities like this (in theviewDidLoad
method):NSFetchRequest *request = [[NSFetchRequest alloc] init]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"Items" inManagedObjectContext:self.managedObjectContext]; [request setEntity:entity]; NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(Item_to_Areas.Name LIKE %@)",[areaManagedObject valueForKey:@"Name"]]; [request setPredicate:predicate]; [request setRelationshipKeyPathsForPrefetching:[NSArray arrayWithObject:@"Item_to_item_comments"]]; NSLog(@"Results: %@", [mutableItemsFetchResults description]); mutableItemsFetchResults = [[managedObjectContext executeFetchRequest:request error:nil] mutableCopy]; [request release];
When the user taps on a row, I select the particular entiny, pass it to a new table view controller in its init method, and push the new view controller to the stack:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { NSLog(@"itemObject: %@", [mutableItemsFetchResults objectAtIndex:indexPath.row]); InspectionItemCommentsViewController *itemCommentsViewController = [[InspectionItemCommentsViewController alloc] initWithManagedObjectContext:self.managedObjectContext itemObject:[mutableItemsFetchResults objectAtIndex:indexPath.row]]; itemCommentsViewController.hidesBottomBarWhenPushed = YES; [self.navigationController pushViewController:itemCommentsViewController animated:YES]; [itemCommentsViewController release]; }
In the first block the NSLog output shows that the "Item_to_item_comments" relationship entities were retrieved, but in the second, that it wasn't even though I invoked [request setRelationshipKeyPathsForPrefetching:[NSArray arrayWithObject:@"Item_to_item_comments"]].
Here is part of the first NSLog output:
Results: ( "<NSManagedObject: 0xb356b70> (entity: Items; id: 0xb34fe60 <x-coredata://E43A90B5-AF0E- 4394-B4A7-5EFE74E181F8/Items/p1> ; data: {\n Clean = nil;\n Description = \"\";\n ItemToInformation = \"<relationship fault: 0x5e1ef00 'ItemToInformation'>\";\n \"Item_to_Areas\" = \"0xb33fd30 <x-coredata://E43A90B5-AF0E-4394-B4A7-5EFE74E181F8/Areas/p1>\";\n \"Item_to_item_comments\" = \"<relationship fault: 0x5e1d300 'Item_to_item_comments'>\";\n Keys = nil;\n Name = Other;\n \"Tenant_agrees\" = nil;\n Undamaged = nil;\n Working = nil;\n})", "<NSManagedObject: 0xb35a930> (entity: Items; id: 0xb32acc0 <x-coredata://E43A90B5-AF0E-4394-B4A7-5EFE74E181F8/Items/p2> ; data: {\n Clean = nil;\n Description = \"\";\n ItemToInformation = \"<relationship fault: 0x790de40 'ItemToInformation'>\";\n \"Item_to_Areas\" = \"0xb33fd30 <x-coredata://E43A90B5-AF0E-4394-B4A7-5EFE74E181F8/Areas/p1>\";\n \"Item_to_item_comments\" = (\n \"0xb35bcb0 <x-coredata://E43A90B5-AF0E-4394-B4A7-5EFE74E181F8/Item_Comments/p13>\",\n \"0xb35bcd0 <x-coredata://E43A90B5-AF0E-4394-B4A7-5EFE74E181F8/Item_Comments/p37>\",\n \"0xb35bca0 <x-coredata://E43A90B5-AF0E-4394-B4A7-5EFE74E181F8/Item_Comments/p5>\",\n \"0xb35bcc0 <x-coredata://E43A90B5-AF0E-4394-B4A7-5EFE74E181F8/Item_Comments/p26>\"\n );\n Keys = nil;\n Name = Lights;\n \"Tenant_agrees\" = nil;\n Undamaged = nil;\n Working = nil;\n})",
You can see that the Items entities are fetched, including
Item_to_item_comments
. Here's the second NSLog:itemObject: <NSManagedObject: 0xe20af50> (entity: Items; id: 0xe209fc0 <x- coredata://E43A90B5-AF0E-4394-B4A7-5EFE74E181F8/Items/p2> ; data: { Clean = nil; Description = ""; ItemToInformation = "<relationship fault: 0xe302e40 'ItemToInformation'>"; "Item_to_Areas" = "0xe500b90 <x-coredata://E43A90B5-AF0E-4394-B4A7-5EFE74E181F8/Areas/p1>"; "Item_to_item_comments" = "<relationship fault: 0xe302e60 'Item_to_item_comments'>"; Keys = nil; Name = Lights; "Tenant_agrees" = nil; Undamaged = nil; Working = nil; })
Now,
Item_to_item_comments
is fault. Similarly, in the pushed view controller, the Items entity is passed, butItem_to_item_comments
is not.I think I am missing something obvious, but after a day spend on this problem, I can't figure it out.
Any help would be appreciated.
Peter
原文:https://stackoverflow.com/questions/3123950
最满意答案
在IPython中,你可以调用
%paste
它将剪贴板粘贴到终端中。注:据我所知,你应该安装
tkinter
使用%paste
。The
%paste
command works, but what I was actually looking for was%doctest_mode
. More cool hacks can be found here
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