EF code first - Model compatibility cannot be checked because the database does not contain model metadata

问题

I have enabled automatic migrations. Then, I deleted my whole db. Next, i executed Update-database from command console, and it recreated my db. Then, I started my application only to see this error:

Model compatibility cannot be checked because the database does not contain model metadata. Model compatibility can only be checked for databases created using Code First or Code First Migrations.

So what exactly is that metadata, and how can I point entity framework to it?

PS. My database contains table named MigrationsHistory.

回答1:

Here is a detailed description of the possible ways to resolve this which I wrote a while ago...
(not exactly what you're experiencing, hence not a duplicate per se, but with different scenarios in mind)

https://stackoverflow.com/a/10255051/417747

To summarize...

What works for me is to use Update-Database -Script

That creates a script with a 'migration difference', which you can manually apply as an SQL script on the target server database (and you should get the right migration table rows inserted etc.).

If that still doesn't work - you can still do two things...

a) remove the migration table (target - under system tables) - as per http://blogs.msdn.com/b/adonet/archive/2012/02/09/ef-4-3-automatic-migrations-walkthrough.aspx comments in there - that should fail back to previous behavior and if you're certain that your Db-s are the same - it's just going to 'trust you',

b) as a last resort I used - make a Update-Database -Script of the full schema (e.g. by initializing an empty db which should force a 'full script'), find the INSERT INTO [__MigrationHistory] records, just run those, insert them into the database, and make sure that your databases - and code match,

that should make things run in sync again.

if it helps

回答2:

Add this to your context:

protected override void OnModelCreating(ModelBuilder modelBuilder) 
{
    modelBuilder.Conventions.Remove<IncludeMetadataConvention>();
}

回答3:

Detach your local Database say example 'database1.mdf' from visual studio 'server explorer' and then open SQL server management studio right click on Databases > Attach and then browse the same 'database1.mdf' file .If you doesn't have access then copy&past both the mdf and ldf files into c drive and do attach.

Then open new query window on sql server then do copy your identity tables as like below query.

*'select * into [__MigrationHistory] from Database1.dbo.__MigrationHistory '*

回答4:

Package Manager Console > Enable-Migrations -EnableAutomaticMigrations
Configure Migrations/Configuration.cs
Package Manager Console > Update-Database

回答5:

I use Entity Framework 6 , SQL 2008 R2 , VS 2013.
To solve this problem only use the following procedure :

1) delete existing db ( existing database that created with EF model{code first})
2) Run APP again.

Fore example query code (in Layout):
this code create db if my model is change and search username in user table.

<body>
    @{
        // Delete && Create ...
        Database.SetInitializer(new DropCreateDatabaseIfModelChanges<DBContext>());

        var db = new DBContext();
        var SearchingUser = db.Users.Where(c => c.UserName == "qwertyui");
        if (SearchingUser.Count() == 0) {
            var User = new Users { UserName = "qwertyui",Password = "12345678" };
            db.Users.Add(User);
            db.SaveChanges();
        }

    }


    @RenderSection("scripts", required: false)
    @RenderBody()
</body>

来源：https://stackoverflow.com/questions/15396992/ef-code-first-model-compatibility-cannot-be-checked-because-the-database-does

标签

entity-framework

migration