Question

我正在使用ASP.NET MVC 3，并通过MVC音乐商店和其他来源学习。我能够创建一个数据库并让它活着，但奇怪的是它在它出现后大约5个小时它发生故障并且出现以下错误和堆栈跟踪：

注意：每当我发布网站时，似乎也是如此。我必须手动删除数据库，以便重新创建它然后它将工作。但是现在我活着，我不能这样做，因为数据已经存储在那里，我不想重做。

File already exists. Try using a different database name. [ File name = C:\HostingSpaces\...\wwwroot\App_Data\Test.sdf ]

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.Data.SqlServerCe.SqlCeException: File already exists. Try using a different database name. [ File name = C:\HostingSpaces\mtnp55\pricexperience.com\wwwroot\App_Data\Test.sdf ]

Source Error: 

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace: 


[SqlCeException (0x80004005): File already exists. Try using a different database name. [ File name = C:\HostingSpaces\...\wwwroot\App_Data\Test.sdf ]]
   System.Data.SqlServerCe.SqlCeEngine.ProcessResults(IntPtr pError, Int32 hr) +72
   System.Data.SqlServerCe.SqlCeEngine.CreateDatabase() +658
   System.Data.SqlServerCe.SqlCeProviderServices.DbCreateDatabase(DbConnection connection, Nullable`1 timeOut, StoreItemCollection storeItemCollection) +194
   System.Data.Objects.ObjectContext.CreateDatabase() +84
   System.Data.Entity.Internal.DatabaseOperations.Create(ObjectContext objectContext) +8
   System.Data.Entity.Database.Create() +76
   System.Data.Entity.CreateDatabaseIfNotExists`1.InitializeDatabase(TContext context) +387
   System.Data.Entity.<>c__DisplayClass2`1.<SetInitializerInternal>b__0(DbContext c) +75
   System.Data.Entity.Internal.<>c__DisplayClass5.<PerformDatabaseInitialization>b__3() +19
   System.Data.Entity.Internal.InternalContext.PerformInitializationAction(Action action) +72
   System.Data.Entity.Internal.InternalContext.PerformDatabaseInitialization() +169
   System.Data.Entity.Internal.LazyInternalContext.<InitializeDatabase>b__4(InternalContext c) +7
   System.Data.Entity.Internal.RetryAction`1.PerformAction(TInput input) +118
   System.Data.Entity.Internal.LazyInternalContext.InitializeDatabaseAction(Action`1 action) +190
   System.Data.Entity.Internal.LazyInternalContext.InitializeDatabase() +73
   System.Data.Entity.Internal.InternalContext.GetEntitySetAndBaseTypeForType(Type entityType) +28
   System.Data.Entity.Internal.Linq.InternalSet`1.Initialize() +62
   System.Data.Entity.Internal.Linq.InternalSet`1.get_InternalContext() +15
   System.Data.Entity.Infrastructure.DbQuery`1.System.Linq.IQueryable.get_Provider() +37
   System.Linq.Queryable.Where(IQueryable`1 source, Expression`1 predicate) +63
   PriceXperience.Controllers.AppsController.ViewLeaderboards(Int32 gameId) in C:\Users\Public\Documents\Development\...\Controllers\AppsController.cs:42
   lambda_method(Closure , ControllerBase , Object[] ) +101
   System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters) +17
   System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) +208
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +27
   System.Web.Mvc.<>c__DisplayClass15.<InvokeActionMethodWithFilters>b__12() +55
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation) +263
   System.Web.Mvc.<>c__DisplayClass17.<InvokeActionMethodWithFilters>b__14() +19
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodWithFilters(ControllerContext controllerContext, IList`1 filters, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +191
   System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +343
   System.Web.Mvc.Controller.ExecuteCore() +116
   System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) +97
   System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext requestContext) +10
   System.Web.Mvc.<>c__DisplayClassb.<BeginProcessRequest>b__5() +37
   System.Web.Mvc.Async.<>c__DisplayClass1.<MakeVoidDelegate>b__0() +21
   System.Web.Mvc.Async.<>c__DisplayClass8`1.<BeginSynchronous>b__7(IAsyncResult _) +12
   System.Web.Mvc.Async.WrappedAsyncResult`1.End() +62
   System.Web.Mvc.<>c__DisplayClasse.<EndProcessRequest>b__d() +50
   System.Web.Mvc.SecurityUtil.<GetCallInAppTrustThunk>b__0(Action f) +7
   System.Web.Mvc.SecurityUtil.ProcessInApplicationTrust(Action action) +22
   System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +60
   System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +8841105
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +184

我尝试了很多东西，但仍然无法弄清楚为什么会这样做。我确实有一个数据库初始化。

 System.Data.Entity.Database.SetInitializer<MobileEntities>(new SampleData());

public class SampleData : CreateDatabaseIfNotExists<MobileEntities>

我尝试访问数据库时运行的代码如下：

public ActionResult ViewLeaderboards(int gameId)
        {
            var leaderboards = from u in mobileDB.Scores
                               where u.GameId == gameId
                               select u;

            return View(leaderboards.OrderByDescending(u => u.Score).ToList());
        }

Answer 1

发布时，您需要确保从Global.asax中删除初始化程序。初始化程序仅用于填充测试数据，不应在生产期间使用。我还记得在某处读取将初始化程序设置为null可能有效。

Database.SetInitializer<MyContext>(null);

或者只是在发布之前注释掉你调用SetInitializer的行。我还在发布之前从项目中排除了我的Initializer类。

Answer 2

Code First上下文的默认策略是CreateDatabaseIfNotExists的一个实例。

有必要包含

Database.SetInitializer<MyContext>(null);

这样就不会调用默认初始值设定项，然后可能会出错！此外，在将通用标记设置为null或编译器将给出错误时，必须包含通用标记。

EF4尝试重新创建数据库，即使它已经存在了？

2 个答案: