Why is EF4 trying to re-create my database even though the model hasn't changed?
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28-09-2019 - |
문제
I have an ASP.NET MVC 3 Beta website using SQL Server CE 4.0. With both ScottGu's NerdDinner example and my own code, I will sometimes get the following exception as soon as I try to access the database:
File already exists. Try using a different database name. [ File name = D:\Sourcecode\NerdDinner\NerdDinner\App_Data\NerdDinners.sdf ] Line 17: public ActionResult Index() Line 18: { Line 19: var dinners = from d in nerdDinners.Dinners Line 20: where d.EventDate > DateTime.Now Line 21: select d; [SqlCeException (0x80004005): File already exists. Try using a different database name. [ File name = D:\Sourcecode\NerdDinner\NerdDinner\App_Data\NerdDinners.sdf ]] System.Data.SqlServerCe.SqlCeEngine.ProcessResults(IntPtr pError, Int32 hr) +92 System.Data.SqlServerCe.SqlCeEngine.CreateDatabase() +1584 System.Data.SqlServerCe.SqlCeProviderServices.DbCreateDatabase(DbConnection connection, Nullable`1 timeOut, StoreItemCollection storeItemCollection) +287 System.Data.Objects.ObjectContext.CreateDatabase() +84 System.Data.Entity.Internal.DatabaseOperations.Create(ObjectContext objectContext) +35 System.Data.Entity.Infrastructure.Database.Create() +70 System.Data.Entity.Infrastructure.CreateDatabaseOnlyIfNotExists`1.InitializeDatabase(TContext context) +360 System.Data.Entity.Infrastructure.Database.Initialize() +272 System.Data.Entity.Internal.InternalContext.Initialize() +90 System.Data.Entity.Internal.InternalContext.GetEntitySetAndBaseTypeForType(Type entityType) +34 System.Data.Entity.Internal.Linq.EfInternalQuery`1.Initialize() +140 System.Data.Entity.Internal.Linq.EfInternalQuery`1.get_Provider() +29 System.Data.Entity.Infrastructure.DbQuery`1.System.Linq.IQueryable.get_Provider() +34 System.Linq.Queryable.Where(IQueryable`1 source, Expression`1 predicate) +63 NerdDinner.Controllers.HomeController.Index() in D:\Sourcecode\NerdDinner\NerdDinner\Controllers\HomeController.cs:19
I cannot figure out why this works sometimes with an existing .dbf file and other times it complains. I have even tried explicitly setting the default behaviour with
Database.SetInitializer(new CreateDatabaseOnlyIfNotExists<...>());
Has anyone else experienced this?
- Restarting Cassini doesn't seem to make a difference.
- Hitting refresh in IE after receiving this error will make the exact same page load properly.
해결책
Install and use SQL Server CE CTP1, which is still downloadable on Microsoft sites. This solved my problem with that.
다른 팁
Sorry to resurrect such an old question, but I was experiencing this today and have found a workaround which does not involve installing an older version of the CTP.
From The correct url for the blogpost is http://www.hanselman.com/blog/PDC10BuildingABlogWithMicrosoftUnnamedPackageOfWebLove.aspx (about half-way through the blog post)
*Go into your AppStart_SQLCEEntityFramework.cs file and the DefaultConnectionFactory line to this:*
Database.DefaultConnectionFactory = new SqlCeConnectionFactory(
"System.Data.SqlServerCe.4.0",
HostingEnvironment.MapPath("~/App_Data/"),"");
My particular database is placed in the App_Data folder but I'm assuming that if yours is not you should be able to change the path to suit and it will work.
Hope this helps!
It looks like this is a recently discovered bug. MSDN Forum
The workaround is to re-install SQL Server CE 4.0 CTP 1 download
I had the same problem today with released MVC3 and SQL Server CE 4.0 downloaded with NuGet and it was resolved by uncommenting the line:
DbDatabase.SetInitializer(new CreateCeDatabaseIfNotExists<MyContext>());
And replacing MyContext with the context class that was inheriting from DBContext in the models folder.
The final SQL Compact Edition 4.0 is out and after installing it the issue is not happening anymore. Here is the announcement from the team blog: