Stop Entity Framework from modifying database

问题:

I'm starting to play around with the code-first approach to the entity framework, primarily so that I can decorate my properties with annotations for display in my view (otherwise, right now I have to create a class that is nearly identical to the one that entity framework generated for me just so I can add annotations, and then copy the data from one object to the next).

Right now it looks like when I start my application it is trying to create a database.

I do not want entity framework to ever modify my database. No. Not ever. Don't even try it. It really isn't that hard to modify databases; I would feel much more comfortable if I did that myself. I don't need a framework to hold my hand when designing a database.

Can I tell the framework to stop trying to modify my database? I'm very hesitant to use code-first now as the fact that it's trying to modify my database is rather frightening. Even in development I never want to see it happen.

Am I out of luck?

回答1:

If you don't want EF to create your database, you can disable the database initializer:

public class SchoolDBContext: DbContext 
{
    public SchoolDBContext() : base("SchoolDBConnectionString")
    {            
        //Disable initializer
        Database.SetInitializer<SchoolDBContext>(null);
    }
    public DbSet<Student> Students { get; set; }
    public DbSet<Standard> Standards { get; set; }
}

See http://www.entityframeworktutorial.net/code-first/turn-off-database-initialization-in-code-first.aspx

回答2:

If you want to use EF but never modify the database then you probably don't want code first. You probably want something more like database first.

http://blogs.msdn.com/b/adonet/archive/2011/03/15/ef-4-1-model-amp-database-first-walkthrough.aspx

Links from answer comments:
http://automapper.codeplex.com/
Getting Started with AutoMapper

edit: I misunderstood the goal, you should reference this answer where the following correct code was given:

If you don't want EF to create your database, you can disable the database initializer

Database.SetInitializer<MyContext>(null);

回答3:

When you declare you're initialiser, use the base class:

public class DatabaseInitialiser : CreateDatabaseIfNotExists<MyContext>

rather than :

public class DatabaseInitialiser : RecreateDatabaseIfModelChanges<MyContext>

Or if you use :

Database.SetInitializer<MyContext>(new RecreateDatabaseIfModelChanges<MyContext>);

replace this with :

Database.SetInitializer<MyContext>(new CreateDatabaseIfNotExists<MyContext>);

回答4:

Since code first pretty much exactly does what you describe, I do not understand your question.

If you don't want EF to fiddle with your database, then generate a model from your existing database.