Question

我已尝试过针对类似问题提出的解决方案，但没有运气。获取请求无法找到实体名称'GarmentType'。

这是我的数据模型： enter image description here

在此帮助程序类别的executeFetchRequest中抛出错误：

//
//  GarmentType+Create.m
//  Dressy
//
//  Created by Michael Mangold on 9/4/13.
//  Copyright (c) 2013 Michael Mangold. All rights reserved.
//

#import "GarmentType+Create.h"

@implementation GarmentType (Create)

// Creates or fetches a Core Data GarmentType entity.
+ (GarmentType *)garmentTypeWithName:(NSString *)name inManagedObjectContext:(NSManagedObjectContext *)context
{
    NSLog(@"name:%@ context:%@",name,context);
    GarmentType *garmentType = nil;

    // Build fetch request.
    NSFetchRequest *request          = [NSFetchRequest fetchRequestWithEntityName:@"GarmentType"];
    request.sortDescriptors          = @[[NSSortDescriptor sortDescriptorWithKey:@"name" ascending:YES]];
    request.predicate                = [NSPredicate predicateWithFormat:@"name = %@",name];

    // Execute fetch requesst.
    NSError *error  = nil;
    NSArray *matches = [context executeFetchRequest:request error:&error]; // This is where it dies.

    if (!matches || [matches count] > 1) {
        NSLog(@"Error creating GarmentType.");
    } else if ([matches count] == 0) {
        garmentType          = [NSEntityDescription insertNewObjectForEntityForName:@"GarmentType" inManagedObjectContext:context];
        garmentType.name     = name;
    } else {
        garmentType = [matches lastObject];
    }

    return garmentType;
}

@end

名称记录正确的名称，上下文为非零。

当按下“完成”按钮时，从UITableViewController IBAction调用助手：

- (IBAction)handleDoneButton:(UIBarButtonItem *)sender
{
    // Add garment type to core data.
    [DressyHelper openDocumentUsingBlock:^(UIManagedDocument *document){
        GarmentType *newGarment = [GarmentType garmentTypeWithName:self.garmentTypeNameTextField.text inManagedObjectContext:document.managedObjectContext];
        NSLog(@"newGarment.name:%@",newGarment.name);
    }];
    [self dismissViewControllerAnimated:YES completion:nil];
}

newGarment.name记录正常。

以下是GarmentType的.h：

#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>

@class Garment;

@interface GarmentType : NSManagedObject

@property (nonatomic, retain) NSString * name;
@property (nonatomic, retain) NSSet *garments;
@end

@interface GarmentType (CoreDataGeneratedAccessors)

- (void)addGarmentsObject:(Garment *)value;
- (void)removeGarmentsObject:(Garment *)value;
- (void)addGarments:(NSSet *)values;
- (void)removeGarments:(NSSet *)values;

@end

代码转储的道歉，但我一直在努力解决这个问题。更改实体名称会导致相同的错误，只是将新名称作为未找到的实体。

GarmentType的检查员： enter image description here

例外：

2013-12-10 13:51:50.320 Dressy[4336:70b] name:asdf context:<NSManagedObjectContext: 0x8ad86f0>
2013-12-10 13:51:50.323 Dressy[4336:70b] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'NSFetchRequest could not locate an NSEntityDescription for entity name 'GarmentType''
*** First throw call stack:
(
    0   CoreFoundation                      0x017465e4 __exceptionPreprocess + 180
    1   libobjc.A.dylib                     0x014c98b6 objc_exception_throw + 44
    2   CoreData                            0x019b4b6e -[NSFetchRequest(_NSInternalMethods) _resolveEntityWithContext:] + 510
    3   CoreData                            0x019b34d6 -[NSManagedObjectContext executeFetchRequest:error:] + 70
    4   Dressy                              0x000051de +[GarmentType(Create) garmentTypeWithName:inManagedObjectContext:] + 510
    5   Dressy                              0x00002170 __54-[GarmentTypeAddTableViewController handleDoneButton:]_block_invoke + 208
    6   Dressy                              0x00006d51 __39+[DressyHelper openDocumentUsingBlock:]_block_invoke21 + 97
    7   UIKit                               0x00781f7b __59-[UIDocument saveToURL:forSaveOperation:completionHandler:]_block_invoke570 + 54
    8   libdispatch.dylib                   0x01e43440 _dispatch_barrier_sync_f_slow_invoke + 71
    9   libdispatch.dylib                   0x01e544b0 _dispatch_client_callout + 14
    10  libdispatch.dylib                   0x01e4275e _dispatch_main_queue_callback_4CF + 340
    11  CoreFoundation                      0x017aba5e __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 14
    12  CoreFoundation                      0x016ec6bb __CFRunLoopRun + 1963
    13  CoreFoundation                      0x016ebac3 CFRunLoopRunSpecific + 467
    14  CoreFoundation                      0x016eb8db CFRunLoopRunInMode + 123
    15  GraphicsServices                    0x03a4d9e2 GSEventRunModal + 192
    16  GraphicsServices                    0x03a4d809 GSEventRun + 104
    17  UIKit                               0x00237d3b UIApplicationMain + 1225
    18  Dressy                              0x0000585d main + 141
    19  libdyld.dylib                       0x020e670d start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)

TIA

Answer 1

我终于找到了问题。 .xcdatamodel未包含在目标成员中。在Xcode左侧的导航器窗格中选择xcdatamodel，然后在右侧的Utilities窗格中选择第一个选项卡（File inspector），然后在Target Membership部分中选择数据模型可以解决问题。非常感谢所有回复的人。

enter image description here

Answer 2

具有实体名称的实体图只是拼图的一半。对于每个实体，您将类名定义为什么？这就是fetchRequestWithEntityName:将反对的内容。

编辑：

由于类名被解析，你得到的例外是什么？继续之后，CoreData会解释它有什么问题吗？应用程序是否实际崩溃（我问这是因为如果您为异常设置了断点，Core Data通常会抛出无关紧要的内部异常或导致应用程序崩溃）？

EDIT2：

在我们知道你有一个有效的背景之后，崩溃并没有说明。下一步是，使用以下代码列出在获取请求之前设置的断点处的所有实体：

NSManagedObjectModel *managedObjectModel = [[context persistentStoreCoordinator] managedObjectModel];
NSDictionary *entities = [managedObjectModel entitiesByName];
NSArray *entityNames = [entities allKeys];
NSLog(@"All loaded entities are: %@", entityNames);

Answer 3

在使用新实体创建新模型版本但忘记更新数据文件URL后，我得到了这个：

NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"Data2.0" <==== Here
                                          withExtension:@"mom"
                                           subdirectory:@"Data.momd"];

_managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];

NSFetchRequest无法找到实体名称的NSEntityDescription

3 个答案: