与RestKit轻量级迁移

Question

苹果的文档给了设立（自动）轻量级迁移下面的例子：

NSError *error = nil; 
NSURL *storeURL = <#The URL of a persistent store#>; 
NSPersistentStoreCoordinator *psc = <#The coordinator#>; 
NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys: 
    [NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption, 
    [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil]; 

BOOL success = [psc addPersistentStoreWithType:<#Store type#> 
        configuration:<#Configuration or nil#> URL:storeURL 
        options:options error:&error]; 
if (!success) { 
    // Handle the error. 
} 

但是我使用RestKit，它处理幕后的持续性商店的创建。我的初始化代码的简化版本是这样的：

// Initialize RestKit 
RKObjectManager* objectManager = [RKObjectManager objectManagerWithBaseURL:rootURL]; 

// Create the object store 
objectManager.objectStore = [RKManagedObjectStore objectStoreWithStoreFilename:databaseName     
                   usingSeedDatabaseName:seedDatabaseName 
                    managedObjectModel:nil //Don't need to pass it in. It is infered 
                      delegate:self]; 
// Create Mappings 
... 

// Define Relationships 
... 

// Set Mappings 
... 

我应该在哪里传递给该RestKit创建persistantStore幕后配置选项？

Answer 1

在我的理解中，RestKit位于Core Data之上。因此，即使在使用种子数据库并让RestKit为对象管理器分配对象存储时，也会使用Core Data提供的sqlite数据库。

要启用具有RestKit轻量级迁移，你可以使用在AppDelegate中的- (NSPersistentStoreCoordinator *)persistentStoreCoordinator方法（见本thread）

的AppDelegate

- (NSPersistentStoreCoordinator *)persistentStoreCoordinator 
{ 
    if (__persistentStoreCoordinator != nil) return __persistentStoreCoordinator; 

    NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"thenameofyoursqlite.sqlite"]; 

    NSError *error = nil; 
    __persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]]; 

    NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys: 
    [NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption, 
    [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil]; 

    if (![persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:options error:&error]) 
    { 
     NSLog(@"Auto migration failed, error %@, %@", error, error.userInfo); 
     abort(); 
    } 
} 

Answer 2

可以在RKManagedObjectStore.m添加这些选项，在createPersistentStoreCoordinator方法。

对于RestKit的版本0.10，它已被添加，不确定是否为最新版本。但如果尚未添加，您可以添加自己。该方法的最终外观是这样的。

- (void)createPersistentStoreCoordinator 
{ 
    NSAssert(_managedObjectModel, @"Cannot create persistent store coordinator without a managed object model"); 
    NSAssert(!_persistentStoreCoordinator, @"Cannot create persistent store coordinator: one already exists."); 
    NSURL *storeURL = [NSURL fileURLWithPath:self.pathToStoreFile]; 

    NSError *error; 
    _persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:_managedObjectModel]; 

    // Allow inferred migration from the original version of the application. 
    NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys: 
          [NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption, 
          [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil]; 

    if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:options error:&error]) { 
     if (self.delegate != nil && [self.delegate respondsToSelector:@selector(managedObjectStore:didFailToCreatePersistentStoreCoordinatorWithError:)]) { 
      [self.delegate managedObjectStore:self didFailToCreatePersistentStoreCoordinatorWithError:error]; 
     } else { 
      NSAssert(NO, @"Managed object store failed to create persistent store coordinator: %@", error); 
     } 
    } 
} 

我已经在我的项目测试了这个，通过增加3个新的实体和重命名旧的实体，并没有从设备删除以前的应用程序正在完善。 希望这可以帮助你。