错误信息:

“自数据库创建以来,支持‘AddressBook’上下文的模型已经发生了变化。手动删除/更新数据库,或者调用database。带有IDatabaseInitializer实例的SetInitializer。例如,RecreateDatabaseIfModelChanges策略将自动删除并重新创建数据库,并可选地为其添加新数据。”

我正在尝试使用代码优先功能,以下是我写的:

var modelBuilder = new ModelBuilder();
var model = modelBuilder.CreateModel();
using (AddressBook context = new AddressBook(model))
{
    var contact = new Contact
    {
        ContactID = 10000,
        FirstName = "Brian",
        LastName = "Lara",
        ModifiedDate = DateTime.Now,
        AddDate = DateTime.Now,
        Title = "Mr."

    };
    context.contacts.Add(contact);
    int result = context.SaveChanges();
    Console.WriteLine("Result :- "+ result.ToString());
}

上下文类:

public class AddressBook : DbContext
{
    public AddressBook()
    { }
    public AddressBook(DbModel AddressBook)
        : base(AddressBook)
    {

    }
    public DbSet<Contact> contacts { get; set; }
    public DbSet<Address> Addresses { get; set; }
}

和连接字符串:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <connectionStrings>
    <add name="AddressBook" providerName="System.Data.SqlClient"  
         connectionString="Data Source=MyMachine;Initial Catalog=AddressBook;
         Integrated Security=True;MultipleActiveResultSets=True;"/>
    </connectionStrings>
</configuration>

因此,数据库名称是“AddressBook”,当我试图将联系人对象添加到上下文时发生错误。我遗漏了什么吗?


当前回答

我有这个问题,原来是一个项目指向SQLExpress,但有问题的是指向LocalDb。(在它们各自的web.config中)。愚蠢的疏忽,但值得注意的是,如果其他人正在排除这个问题。

其他回答

I am reading the Pro ASP.NET MVC 4 book as well, and ran into the same problem you were having. For me, I started having the problem after making the changes prescribed in the 'Adding Model Validation' section of the book. The way I resolved the problem is by moving my database from the localdb to the full-blown SQL Server 2012 server. (BTW, I know that I am lucky I could switch to the full-blown version, so don't hate me. ;-))) There must be something with the communication to the db that is causing the problem.

I had the same issue - re-adding the migration and updating the database didn't work and none of the answers above seemed right. Then inspiration hit me - I'm using multiple tiers (one web, one data, and one business). The data layer has the context and all the models. The web layer never threw this exception - it was the business layer (which I set as console application for testing and debugging). Turns out the business layer wasn't using the right connection string to get the db and make the context. So I added the connection string to the app config of the business layer (and the data layer) and viola it works. Putting this here for others who may encounter the same issue.

尝试使用Database SetInitializer,它属于using System.Data.Entity;

在Global.asax

protected void Application_Start()
{
    Database.SetInitializer(new DropCreateDatabaseIfModelChanges<yourContext>());
}

这将在每次模型更改时创建新的数据库。但是您的数据库将是空的。为了用虚拟数据填充它,你可以使用播种。你可以实现为:

播种::

protected void Application_Start()
{
    Database.SetInitializer(new AddressBookInitializer());
                ----rest code---
}
public class AddressBookInitializer : DropCreateDatabaseIfModelChanges<AddressBook>
{
    protected override void Seed(AddressBook context)
    {
        context.yourmodel.Add(
        {

        });
        base.Seed(context);
    }

}

或者你可以把这一行放在你的Global.asax.cs文件中的Application_Start():

System.Data.Entity.Database.SetInitializer(new System.Data.Entity.DropCreateDatabaseIfModelChanges<ProjectName.Path.Context>());

确保将ProjectName.Path.Context更改为您的名称空间和上下文。如果先使用代码,那么每当对模式进行任何更改时,都会删除并创建一个新数据库。

刚刚找到答案,想在这里更新。只需要做以下事情。

public class AddressBook: DbContext
{
   protected override void OnModelCreating(ModelBuilder modelBuilder)
   {
    modelBuilder.IncludeMetadataInDatabase = false;
   }
}