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

以下是Jeff在Scott Gu的博客上发布的一些信息:

For those who are seeing this exception: "The model backing the 'Production' context has changed since the database was created. Either manually delete/update the database, or call Database.SetInitializer with an IDatabaseInitializer instance." Here is what is going on and what to do about it: When a model is first created, we run a DatabaseInitializer to do things like create the database if it's not there or add seed data. The default DatabaseInitializer tries to compare the database schema needed to use the model with a hash of the schema stored in an EdmMetadata table that is created with a database (when Code First is the one creating the database). Existing databases won’t have the EdmMetadata table and so won’t have the hash…and the implementation today will throw if that table is missing. We'll work on changing this behavior before we ship the fial version since it is the default. Until then, existing databases do not generally need any database initializer so it can be turned off for your context type by calling: Database.SetInitializer<YourDbContext>(null); Jeff

其他回答

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。

以下是Jeff在Scott Gu的博客上发布的一些信息:

For those who are seeing this exception: "The model backing the 'Production' context has changed since the database was created. Either manually delete/update the database, or call Database.SetInitializer with an IDatabaseInitializer instance." Here is what is going on and what to do about it: When a model is first created, we run a DatabaseInitializer to do things like create the database if it's not there or add seed data. The default DatabaseInitializer tries to compare the database schema needed to use the model with a hash of the schema stored in an EdmMetadata table that is created with a database (when Code First is the one creating the database). Existing databases won’t have the EdmMetadata table and so won’t have the hash…and the implementation today will throw if that table is missing. We'll work on changing this behavior before we ship the fial version since it is the default. Until then, existing databases do not generally need any database initializer so it can be turned off for your context type by calling: Database.SetInitializer<YourDbContext>(null); Jeff

检查以下步骤

Database.SetInitializer(空);——> Global.asax.cs

2.

你的Context类名应该与之匹配 检查它

此修复在CTP5之后不再有效。

你必须执行database。setinitializer <YourContext>(null);

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;
   }
}