添加新字段时出现MobileServiceTableOperationError [英] MobileServiceTableOperationError When Adding New Field
问题描述
我有一个基于脱机工作清单示例的Azure移动服务项目:
I have an Azure Mobile Services project that is based off of the offline to do list example:
具有脱机数据的示例应用程序正在按预期方式工作.问题是当我想用新字段修改ToDoItem时.如果我使用以下新字段(Windows应用程序TodoItem类和AzureMobileService应用程序TodoItem类)修改ToDoItem类:
The example application with offline data is working as expected. The problem is when I want to modify the ToDoItem with a new field. If I modify the ToDoItem class with a new field (both the Windows app TodoItem class and the AzureMobileService app TodoItem class) with the following:
[JsonProperty(PropertyName = "NewData")]
public byte[] NewData { get; set; }
当我尝试添加新项目时:
When I try to add a new item:
await MobileService.SyncContext.PushAsync();
我得到了错误:
A first chance exception of type 'Microsoft.WindowsAzure.MobileServices.Sync.MobileServicePushFailedException' occurred in mscorlib.dll
Additional information: Push operation has failed. See the PushResult for details.
PushResult然后出现此错误:
The PushResult then has this error:
{Microsoft.WindowsAzure.MobileServices.Sync.MobileServiceTableOperationError}
据我了解，Azure移动服务支持动态架构，因此我不必手动更新数据库.
It is my understanding that the Azure Mobile Service supports Dynamic Schema, so I should not have to manually update the database.
知道我在做什么错吗?
我正在使用.NET后端.
I am using a .NET backend.
更新1/31/2015
如果我从以下位置修改MobileServiceInitializer:
If I modify the MobileServiceInitializer from:
public class MobileServiceInitializer : DropCreateDatabaseIfModelChanges<MobileServiceContext>
收件人:
public class MobileServiceInitializer : ClearDatabaseSchemaIfModelChanges<MobileServiceContext>
它将正确更新数据库，但是当然会清除表中的所有数据.知道为什么DropCreateDatabaseIfModelChanges会引发错误吗?
It will correctly update the database, but of course clears all of my data in the table. Any idea why DropCreateDatabaseIfModelChanges is throwing the error?
推荐答案
这可能是因为Azure移动服务无权删除数据库.在此处查看此博客: http://blogs.msdn.com/b/writingdata_services/archive/2014/03/28/mobile-services-net-backend-initializers-and-model-updates.aspx
This may be because Azure Mobile Services doesn't have permission to Drop your database. See this blog here: http://blogs.msdn.com/b/writingdata_services/archive/2014/03/28/mobile-services-net-backend-initializers-and-model-updates.aspx
如果这是您的问题，则博客列出了两个选择:
The blog lays out two options, if this is your problem:
-
删除现有表-遇到您正在谈论的所有问题
Drop existing tables - Which has all the problems you're talking about
启用代码优先迁移-允许您保留数据.代码优先迁移有点棘手，因此请为此做好准备，但这是解决您的问题的一种方法.上面的博客对此进行了介绍，但这是在EF中进行迁移的更深入的演示:
Enable Code First Migration - which allows you to keep your data. Code First migration is a bit tricky, so be prepared for that, but it is one solution for your problem. The Blog above goes into this a bit but this is a more depth demo of doing a Migration in EF: https://msdn.microsoft.com/en-us/data/JJ591621.aspx
这篇关于添加新字段时出现MobileServiceTableOperationError的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
