iPhone核心数据轻量级迁移：无法合并模型 [英] iPhone Core Data Lightweight Migration: Can't merge models

问题描述

我刚刚开始使用iPhone核心数据，我在轻量级迁移中遇到了一个问题。

• 重新生成模型类文件


• 将新模型版本设为当前版本


• 在AppDelegate中生成的模板中添加了以下代码
  
  
  

  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] li>
  

• 最后，我在运行应用之前做了一个干净的构建。

当应用程式崩溃时，我收到以下错误...

 无法完成操作。 （Cocoa错误134140.）UserInfo = 0x622b350 {reason =无法找到或自动推断迁移的映射模型
  

现在调试我添加了以下代码...

  NSError * error = nil; 
 NSDictionary * sourceMetadata = [NSPersistentStoreCoordinator metadataForPersistentStoreOfType：NSSQLiteStoreType URL：storeURL error：& error]; 
 
 if（！sourceMetadata）{
 NSLog（@sourceMetadata is nil）; 
} else {
 NSLog（@sourceMetadata is％@，sourceMetadata）; 
} 
  

这会显示以下结果...

  2011-01-20 18：18：41.018 MyApp [4438：207 ] sourceMetadata is {
 NSPersistenceFrameworkVersion = 248; 
 NSStoreModelVersionHashes = {
 Fugitive =< e33370b6 e7ca3101 f91d2595 1e8bfe01 3e7fb4de 6ef2a31d 9e50237b b313d390> ;; 
}; 
 NSStoreModelVersionHashesVersion = 3 ; 
 NSStoreModelVersionIdentifiers =（
）; 
 NSStoreType = SQLite; 
 NSStoreUUID =E711F65F-3C5A-4889-872B-6541E4B2863A; 
_NSAutoVacuumLevel= 2; 
} 
  

我检查了应用程序包> MyApp.momd> VersionInfo.plist文件

它有以下内容...

 <？xml version =1.0encoding =UTF-8？> 
<！DOCTYPE plist PUBLIC -  // Apple // DTD PLIST 1.0 // ENhttp://www.apple.com/DTDs/PropertyList-1.0.dtd\"> 
< plist version =1.0> 
< dict> 
< key> NSManagedObjectModel_CurrentVersionName< / key> 
< string> MyApp 2< / string> 
< key> NSManagedObjectModel_VersionHashes< / key> 
< dict> 
< key> MyApp< / key> 
< dict> 
< key> Fugitive< / key> 
< data> 
 4zNwtufKMQH5HSWVHov + AT5 / tN5u8qMdnlAje7MT05A = 
< / data> 
< / dict> 
< key> MyApp 2< / key> 
< dict> 
< key> Fugitive< / key> 
< data> 
 N58Lf4BNpACzrsHAb1 + BQImgjsBZ + u5G0wGUyt84 + Ec = 
< / data> 
< / dict> 
< / dict> 
< / dict> 
< / plist> 
  

我在这里缺少什么？

UPDATE ：问题是我在模型中错过的默认值属性。

解决方案

p>您可以尝试强制Core Data推断映射模型：

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

如果对模型的更改是微不足道的，那么Core Data可能能够推断映射模型。如果失败，那么您可能需要创建一个映射模型（并恢复到当前使用的选项）。

映射模型很容易创建。请注意，如果您更改数据模型，则还需要更新映射。

您可能想要查看这是SO post 。

I just started with iPhone core data and I ran into a problem in lightweight migration.

• I added two new fields to my old model
• Regenerated the model class files
• Made the new model version as current version

• Added the following code in AppDelegate in the template generated

  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]) {

• Then at last, I did a clean build before running the app.

I get the following error when the app crashes...

The operation couldn’t be completed. (Cocoa error 134140.)" UserInfo=0x622b350 {reason=Can't find or automatically infer mapping model for migration

Now to debug I added the following code...

    NSError *error = nil;
    NSDictionary *sourceMetadata = [NSPersistentStoreCoordinator metadataForPersistentStoreOfType:NSSQLiteStoreType URL:storeURL error:&error];

    if (!sourceMetadata) {
        NSLog(@"sourceMetadata is nil");
    } else {
        NSLog(@"sourceMetadata is %@", sourceMetadata);
    }

This displays the following result...

2011-01-20 18:18:41.018 MyApp[4438:207] sourceMetadata is {
    NSPersistenceFrameworkVersion = 248;
    NSStoreModelVersionHashes =     {
        Fugitive = <e33370b6 e7ca3101 f91d2595 1e8bfe01 3e7fb4de 6ef2a31d 9e50237b b313d390>;
    };
    NSStoreModelVersionHashesVersion = 3;
    NSStoreModelVersionIdentifiers =     (
    );
    NSStoreType = SQLite;
    NSStoreUUID = "E711F65F-3C5A-4889-872B-6541E4B2863A";
    "_NSAutoVacuumLevel" = 2;
}

I checked the app bundle > MyApp.momd > VersionInfo.plist file

its got the following contents...

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>NSManagedObjectModel_CurrentVersionName</key>
    <string>MyApp 2</string>
    <key>NSManagedObjectModel_VersionHashes</key>
    <dict>
        <key>MyApp</key>
        <dict>
            <key>Fugitive</key>
            <data>
            4zNwtufKMQH5HSWVHov+AT5/tN5u8qMdnlAje7MT05A=
            </data>
        </dict>
        <key>MyApp 2</key>
        <dict>
            <key>Fugitive</key>
            <data>
            N58Lf4BNpACzrsHAb1+BQImgjsBZ+u5G0wGUyt84+Ec=
            </data>
        </dict>
    </dict>
</dict>
</plist>

What am I missing here?

UPDATE: The problem turned out to be a default value attribute that I had missed in the model.

解决方案

You might try forcing Core Data to infer a mapping model:

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

If the changes to your model were trivial, then Core Data may be able to infer a mapping model. If that fails, then you will probably need to create a mapping model (and revert to the options that you are currently using).

Mapping models are easy to create. Be mindful, though, if you change a data model then you will need to update the mapping, too.

You might want to check out this SO post.

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