Code first database not being created from model

问题

I'm creating a basic MVC application using asp.net and the entity framework. I've been following this tutorial, altering the data model to fit my needs.

I've created a database model, and generated the MVC controller. When I run the application and navigate to a page that requires the database I get the following error when the line return View(db.Servers.ToList()); within the controller is reached:

"An exception of type 'System.InvalidOperationException' occurred in EntityFramework.dll. Additional information: Failed to set database initializer of type 'Purely_Servers.DAL.serverInitializer, Purely_Servers' for DbContext type 'Purely_Servers.DAL.serverContext, Purely_Servers' specified in the application configuration."

There are two inner exceptions : "When using relative paths, make sure the current directory is correct" and "Verify the file exists at the current location".

My code

serverContext.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using Purely_Servers.Models;
using System.Data.Entity;
using System.Data.Entity.ModelConfiguration.Conventions;

namespace Purely_Servers.DAL
{
    public class serverContext : DbContext
    {

        public serverContext() : base("serverContext")
        {
        }

        // create a DbSet property for each entity set
        public DbSet<server> Servers {get; set;}
        public DbSet<user> Users {get; set;}
        public DbSet<faculty> Faculties {get; set;}
        public DbSet<admin> Admins {get; set;}

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

serverInitializer.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data.Entity;
using Purely_Servers.Models;

namespace Purely_Servers.DAL
{
    public class serverInitializer : System.Data.Entity.DropCreateDatabaseIfModelChanges<serverContext>
    {
        protected override void Seed(serverContext context)
        {
            // create the servers
            var servers = new List<server>
            {
                new server{.......}
            };
            // add them to the dbcontext
            servers.ForEach(s => context.Servers.Add(s));
            context.SaveChanges();


            // create the admins
            var admins = new List<admin>
            {
                new admin{.....}
            };
            // add them to the dbcontext
            admins.ForEach(a => context.Admins.Add(a));
            context.SaveChanges();

            // create the users
            var users = new List<user>
            {
                new user{......}
            };
            // add them to the dbcontext
            users.ForEach(u => context.Users.Add(u));
            context.SaveChanges();

            // create the school
            var faculties = new List<faculty>
            {
                new faculty{.....},

            };
            // add them to the context
            faculties.ForEach(f => context.Faculties.Add(f));
            context.SaveChanges();
        }
    }
}

Web.config

<connectionStrings>
  <add name="serverContext" connectionString="Data Source=(LocalDb)\v11.0;Initial Catalog=235Servers;Integrated Security=SSPI" providerName="System.Data.SqlClient" />
</connectionStrings>
<entityFramework>
  <contexts>
    <context type="Purely_Servers.DAL.serverContext, Purely_Servers">
      <databaseInitializer type="Purely_Servers.DAL.serverInitializer, Purely_Servers" />
    </context>
  </contexts>
</entityFramework>

Any help much appreciated.

回答1:

Setting the database initializer from config is difficult to get right because your root namespace, assembly name, and DLL name can all be different.

A more strongly typed approach would be:

public class serverContext: DbContext 
{

    public serverContext(): base("serverContext") 
    {
        Database.SetInitializer<serverContext>(new serverInitializer());
        ...

With this you would remove the <context configuration. (but keep the connectionStrings/add config)

来源：https://stackoverflow.com/questions/27713276/code-first-database-not-being-created-from-model