Entity Framework 5 expects CreatedOn column from M

问题:

I am migrating an MVC 3 application from EF 4.3 to EF 5. I noticed that EF 5 expects a CreatedOn column in the __MigrationHistory table, which does not exist as the migrations were created by an older version.

SELECT TOP (1) 
[c].[CreatedOn] AS [CreatedOn]
FROM [dbo].[__MigrationHistory] AS [c]

How do I resolve this issue without wiping my migration history? I am thinking of a query to infer the column's value from the migration name, which is in the following format:

201203111201542_MigrationName

回答1:

The CreatedOn column is no longer required. We attempt to query from it in order to determine whether we need to drop it. i.e. You are upgrading from 4.3 to 5.

回答2:

Just like Filip Cornelissen said, it is a thing between MiniProfiler.EF and Entity Framework 5.0.

Solving/hiding the problem is actually easier than you would think. It is only a "debugging problem" as the error you'll get is only happening during the instantiating period (checking for new migrations), and the error is an "SQL Unhandeld Exception".

So, solving this problem is easy:

Go in Visual Studio to your "DEBUG" tab. Hit the "Exceptions" item. In the new dialog, you open the tree "Common Language Runtime Exceptions". Under "System.Data.SqlClient, uncheck both checkboxes after "System.Data.SqlClient.SqlException". Add it, if it ain't there.

And off ya go!

回答3:

Seems like a thing in EF Code first with migrations enabled, when you upgrade from EF4.* to EF 5.0. And that in combination with MiniProfiler. The table existed in dbo._MigrationHistory under system tables.

You try do a few things:

1. You can add CreatedOn (DateTime) column manually to dbo._MigrationHistory table under System tables folder.
2. You can stop detecting changes by setting Configuration.AutoDetectChangesEnabled = false;
3. Comment this line MiniProfilerEF.Initialize(), disabling EF profiling.

Here is an example of the seed method to add the CreatedOn column. This column will be deleted each time the context is initialized. The seed method is in the Configuration class of the context.

internal sealed class Configuration : DbMigrationsConfiguration<MyContext>
{
    protected override void Seed(MyContext context)
    {
        //  This method will be called after migrating to the latest version.

        // Hide error Invalid column name 'CreatedOn' from mini profiler.
        context.Database.ExecuteSqlCommand(
            @"IF NOT EXISTS(SELECT * FROM sys.columns WHERE object_id = OBJECT_ID('__MigrationHistory') AND name = 'CreatedOn')
                ALTER TABLE dbo.__MigrationHistory ADD CreatedOn datetime NOT NULL CONSTRAINT DF___MigrationHistory_CreatedOn DEFAULT (SYSUTCDATETIME());
        ");
    }
}

回答4:

According to Filip Cornelissen answer following script fixes this problem

--IF OBJECT_ID('dbo.__MigrationHistory') IS NOT NULL

ALTER TABLE dbo.__MigrationHistory ADD CreatedOn DateTime Default GETDATE()
GO
UPDATE dbo.__MigrationHistory SET CreatedOn = GETDATE()

回答5:

Here's a workaround I'm using. Personally, I'm OK with pressing the green arrow twice (Start debugging and then Continue), but if you really want it to stop breaking, try this Post Build Event which will remove the MiniProfiler PDB:

del "$(TargetDir)MiniProfiler.pdb" /q /s

UPDATE: if that's too much work for you, I created a NuGet package:

PM> Install-Package MiniProfilerContrib.EFMigrationsFix