C# 实体框架引发异常-发生与网络相关或特定于实例的错误

我遵循了MVC 3中的教程，并完成了以下操作：

public partial class UserDataBaseDB : DbContext
    {
        public DbSet<User> Users { get; set; }

        public UserDataBaseDB()
            : base(@"UserDataBaseDB")
        {
            if (this.Database.Exists())
            {
                try
                {
                    this.Database.CompatibleWithModel(false);
                }
                catch (InvalidOperationException)
                {
                    this.Database.Delete();
                }
            }

            if (!this.Database.Exists())
            {
                this.Database.Create();
                Seed();
            }
        }

        private void Seed()
        {
            var Mark = new User();
            Mark.ID = 0;
            Mark.MD5Pass = "4297f44b13955235245b2497399d7a93";
            Mark.UserName = "Admin";

            var Troll = new Comment();
            Troll.CommentData = "Fake!";
            Troll.Writer = Mark;

            var Site = new Website();
            Site.Name = "Admin Site";

            Site.Pages.ElementAt(0).Data = "Awesome website!";
            Site.Pages.ElementAt(0).Comments.Add(Troll);

            Mark.Websites.Add(Site);

            Users.Add(Mark);
        }
        public static UserDataBaseDB Create()
        {
            return new UserDataBaseDB();
        }
        public User FindUserByID(int id)
        {
            return (from item in this.Users
                    where item.ID == id
                    select item).SingleOrDefault();
        }

Line 14:             : base(@"UserDataBaseDB")
Line 15:         {
Line 16:             **if (this.Database.Exists())**
Line 17:             {
Line 18:                 try

创建了4个类和一个数据库类：

用户

[有一个]网站列表s[有一个]网页列表s[有一个]评论列表s[每个标记的单词都是它自己的一类]。

然后，我这样创建了一个名为

UserDataBaseDB

的类：

public partial class UserDataBaseDB : DbContext
    {
        public DbSet<User> Users { get; set; }

        public UserDataBaseDB()
            : base(@"UserDataBaseDB")
        {
            if (this.Database.Exists())
            {
                try
                {
                    this.Database.CompatibleWithModel(false);
                }
                catch (InvalidOperationException)
                {
                    this.Database.Delete();
                }
            }

            if (!this.Database.Exists())
            {
                this.Database.Create();
                Seed();
            }
        }

        private void Seed()
        {
            var Mark = new User();
            Mark.ID = 0;
            Mark.MD5Pass = "4297f44b13955235245b2497399d7a93";
            Mark.UserName = "Admin";

            var Troll = new Comment();
            Troll.CommentData = "Fake!";
            Troll.Writer = Mark;

            var Site = new Website();
            Site.Name = "Admin Site";

            Site.Pages.ElementAt(0).Data = "Awesome website!";
            Site.Pages.ElementAt(0).Comments.Add(Troll);

            Mark.Websites.Add(Site);

            Users.Add(Mark);
        }
        public static UserDataBaseDB Create()
        {
            return new UserDataBaseDB();
        }
        public User FindUserByID(int id)
        {
            return (from item in this.Users
                    where item.ID == id
                    select item).SingleOrDefault();
        }

Line 14:             : base(@"UserDataBaseDB")
Line 15:         {
Line 16:             **if (this.Database.Exists())**
Line 17:             {
Line 18:                 try

让标记线为红线。

public partial class UserDataBaseDB : DbContext
    {
        public DbSet<User> Users { get; set; }

        public UserDataBaseDB()
            : base(@"UserDataBaseDB")
        {
            if (this.Database.Exists())
            {
                try
                {
                    this.Database.CompatibleWithModel(false);
                }
                catch (InvalidOperationException)
                {
                    this.Database.Delete();
                }
            }

            if (!this.Database.Exists())
            {
                this.Database.Create();
                Seed();
            }
        }

        private void Seed()
        {
            var Mark = new User();
            Mark.ID = 0;
            Mark.MD5Pass = "4297f44b13955235245b2497399d7a93";
            Mark.UserName = "Admin";

            var Troll = new Comment();
            Troll.CommentData = "Fake!";
            Troll.Writer = Mark;

            var Site = new Website();
            Site.Name = "Admin Site";

            Site.Pages.ElementAt(0).Data = "Awesome website!";
            Site.Pages.ElementAt(0).Comments.Add(Troll);

            Mark.Websites.Add(Site);

            Users.Add(Mark);
        }
        public static UserDataBaseDB Create()
        {
            return new UserDataBaseDB();
        }
        public User FindUserByID(int id)
        {
            return (from item in this.Users
                    where item.ID == id
                    select item).SingleOrDefault();
        }

Line 14:             : base(@"UserDataBaseDB")
Line 15:         {
Line 16:             **if (this.Database.Exists())**
Line 17:             {
Line 18:                 try

我尝试重新安装Entity Framework，也尝试了EFCodeFirst，尝试创建自己的

SqlDataBase

并为其提供连接字符串，但没有任何效果。

public partial class UserDataBaseDB : DbContext
    {
        public DbSet<User> Users { get; set; }

        public UserDataBaseDB()
            : base(@"UserDataBaseDB")
        {
            if (this.Database.Exists())
            {
                try
                {
                    this.Database.CompatibleWithModel(false);
                }
                catch (InvalidOperationException)
                {
                    this.Database.Delete();
                }
            }

            if (!this.Database.Exists())
            {
                this.Database.Create();
                Seed();
            }
        }

        private void Seed()
        {
            var Mark = new User();
            Mark.ID = 0;
            Mark.MD5Pass = "4297f44b13955235245b2497399d7a93";
            Mark.UserName = "Admin";

            var Troll = new Comment();
            Troll.CommentData = "Fake!";
            Troll.Writer = Mark;

            var Site = new Website();
            Site.Name = "Admin Site";

            Site.Pages.ElementAt(0).Data = "Awesome website!";
            Site.Pages.ElementAt(0).Comments.Add(Troll);

            Mark.Websites.Add(Site);

            Users.Add(Mark);
        }
        public static UserDataBaseDB Create()
        {
            return new UserDataBaseDB();
        }
        public User FindUserByID(int id)
        {
            return (from item in this.Users
                    where item.ID == id
                    select item).SingleOrDefault();
        }

Line 14:             : base(@"UserDataBaseDB")
Line 15:         {
Line 16:             **if (this.Database.Exists())**
Line 17:             {
Line 18:                 try

有人知道解决办法吗？谢谢大家!

public partial class UserDataBaseDB : DbContext
    {
        public DbSet<User> Users { get; set; }

        public UserDataBaseDB()
            : base(@"UserDataBaseDB")
        {
            if (this.Database.Exists())
            {
                try
                {
                    this.Database.CompatibleWithModel(false);
                }
                catch (InvalidOperationException)
                {
                    this.Database.Delete();
                }
            }

            if (!this.Database.Exists())
            {
                this.Database.Create();
                Seed();
            }
        }

        private void Seed()
        {
            var Mark = new User();
            Mark.ID = 0;
            Mark.MD5Pass = "4297f44b13955235245b2497399d7a93";
            Mark.UserName = "Admin";

            var Troll = new Comment();
            Troll.CommentData = "Fake!";
            Troll.Writer = Mark;

            var Site = new Website();
            Site.Name = "Admin Site";

            Site.Pages.ElementAt(0).Data = "Awesome website!";
            Site.Pages.ElementAt(0).Comments.Add(Troll);

            Mark.Websites.Add(Site);

            Users.Add(Mark);
        }
        public static UserDataBaseDB Create()
        {
            return new UserDataBaseDB();
        }
        public User FindUserByID(int id)
        {
            return (from item in this.Users
                    where item.ID == id
                    select item).SingleOrDefault();
        }

Line 14:             : base(@"UserDataBaseDB")
Line 15:         {
Line 16:             **if (this.Database.Exists())**
Line 17:             {
Line 18:                 try

---

PS：我正在Win7 64位机器上使用VS Ultimate SP1。

这可能是连接字符串问题，但是我确实看到您正在尝试在构造函数中播种信息并充分使用上下文，我强烈建议您不要这样做。 您可以实现OnModelCreating方法，并在那里尝试初始化代码，或者在应用程序启动中尝试更好的方法。在构造函数中停留似乎是不对的，因为此时初始化才刚刚开始

在上设置断点

if (this.Database.Exists()) if（this.Database.Exists（）） 错误是否在该行之后立即发生？如果是，请三次检查您的连接字符串。你的代码是在一个项目中，还是被分解？确保您正在检查根web项目的web.config中的连接字符串，而不是任何组件的app.config（如果您碰巧正在使用该设计）

每次您首先更改代码等时，是否更改了连接字符串？代码优先连接字符串以上下文类命名，非常简单：

<add name="UserDataBaseDB" connectionString="Data Source=|DataDirectory|test.sdf" providerName="System.Data.SqlServerCe.4.0" /%gt;

你的连接字符串是什么？您的工作站能够连接到sql server吗？谢谢，这很有效。虽然我有另一个问题，从网站上阅读，我将在另一个问题后。