Entity Framework CTP4: where to put SetInitializer?

杀马特。学长 韩版系。学妹 提交于 2019-12-05 00:11:54

问题


I am attempting to add Entity Framework, code first, to an MVC application that's been running with test data, using the CTP4 preview.

I am currently getting this error:

The model backing the 'SchedulerContext' context has changed since the database was created. Either manually delete/update the database, or call Database.SetInitializer with an IDatabaseInitializer instance. For example, the RecreateDatabaseIfModelChanges strategy will automatically delete and recreate the database, and optionally seed it with new data.

I do not want to generate a database at all, as I already have a database. So I tried adding the following to the SchedulerContext constructor:

Database.SetInitializer<SchedulerContext>(new CreateDatabaseOnlyIfNotExists<SchedulerContext>());

which had no effect at all -- I got the same error the next time it ran. The error seems to occur when it is executing a LINQ statement that accesses the database -- the first, I think.

Where should I put this statement, or is this statement the answer to this problem at all?


回答1:


Update

I simply glossed over the fact you already have a database and don't want to create another one...in that case the answer is to put this in your SchedulerContext class

protected override void OnModelCreating(System.Data.Entity.ModelConfiguration.ModelBuilder modelBuilder) {
    modelBuilder.IncludeMetadataInDatabase = false;
}

Old answer

You usually put it in the Global.asax

protected void Application_Start() {
    Database.SetInitializer<SchedulerContext>(new CreateDatabaseOnlyIfNotExists<SchedulerContext>());
}

Note that it will only be initialized on first use of the data context.

Update

public class DataContextInitializer : CreateDatabaseOnlyIfNotExists<SchedulerContext> {
    protected override void Seed(SchedulerContext context) {
    }
}

Then you modify the SetInitializer like so.

System.Data.Entity.Infrastructure.Database.SetInitializer<SchedulerContext>(new  DataContextInitializer());



回答2:


Btw, as of CTP5, this is the proper way of setting the initializer in Global.asax

protected void Application_Start() { System.Data.Entity.Database.DbDatabase.SetInitializer<NerdDinners>(new System.Data.Entity.Database.DropCreateDatabaseIfModelChanges<NerdDinners>()); }




回答3:


In EF 4.1

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



回答4:


The problem is that ADO.NET team creates the connection as

 connectionBuilder = new SqlConnectionStringBuilder(sqlConnection.ConnectionString)
                {
                    InitialCatalog = "master",
                    AttachDBFilename = string.Empty, 
                };

BUT sqlConnection.ConnectionString is the pure connection string specified in the application config file but without password! due to the security reasons, I think ... so then opening such connection fails!


The only possible solution I found is to use integrated security, which means to set the connection string property Integrated Security=SSPI

And we need to wait while there will be a patch or CTP5 ;o)



来源:https://stackoverflow.com/questions/3672919/entity-framework-ctp4-where-to-put-setinitializer