自数据库创建以来，支持<Database>上下文的模型已经更改

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

修改Global.asax.cs，包括Application_Start事件:

Database.SetInitializer<YourDatabaseContext>(
 new DropCreateDatabaseIfModelChanges<YourDatabaseContext>());

2014-01-30 17:10:09

其他回答

在sql Server Management Studio中执行如下sql命令:

delete FROM [dbo].[__MigrationHistory]

2016-06-21 17:28:48

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.

2013-01-24 20:08:57

现在是:

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    Database.SetInitializer<YourDbContext>(null);
    base.OnModelCreating(modelBuilder);
}

在你的YourDbContext.cs文件中。

2011-05-26 18:08:09

这很奇怪，但这里所有的答案对我来说都没用。对于我来说，有效的初始化器

MigrateDatabaseToLatestVersion

以下是我的解决方案(我知道，它可以简单得多，但这就是我使用它的方式):

class MyDbMigrateToLatest : MigrateDatabaseToLatestVersion<MyDbContext, Configuration>
{
}

public class MyDbContext: DbContext
{
    public MyDbContext() : base("DbName")
    {
        SetInitializer();
    }

    public MyDbContext(string connString) : base(connString)
    {
        SetInitializer();
    }

    private static void SetInitializer()
    {
        if (ConfigurationManager.AppSettings["RebuildDatabaseOnStart"] == "true")
            Database.SetInitializer(new MyDbInitializerForTesting());
        else
            Database.SetInitializer(new MyDbMigrateToLatest());
    }
}

public sealed class Configuration : DbMigrationsConfiguration<MyDbContext>
{
    public Configuration()
    {
        AutomaticMigrationsEnabled = true;
    }

    protected override void Seed(MyDbContext context)
    {
        // Whatever
    }
}

MyDbInitializerForTesting只是继承自DropCreateDatabaseAlways，所以在某些特定的情况下(测试)，整个数据库被重建。否则，它已迁移到最新版本。

我的来源:https://msdn.microsoft.com/en-us/data/jj591621.aspx#specific

2015-06-15 07:03:06

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。

2014-01-02 00:18:50

自数据库创建以来，支持<Database>上下文的模型已经更改

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