使用存储库模式时，多个数据库环境 [英] Multiple database contexts when using repository pattern

问题描述

我是有点失落，现在......我从来没有见过关于解决问题的方法这么多不同的信息。但是，让我们从头开始。

I am a bit lost right now... I've never seen this much divergent information regarding solution to the problem. But let us start from the beginning.

我使用ASP.NET MVC与存储库注入控制器，由于Ninject。我有2个简单的实体：管理与创建的博客文章和条目的一个虚拟管理领域的一个列表

I am using ASP.NET MVC with Repositories injected to Controllers, thanks to the Ninject. I have 2 simple Entities: Admin with a list of created blog entries and Entries with one virtual Admin field.

管理

public class Admin
{
    [Key, ScaffoldColumn(false)]
    public int Id { get; set; }

    [Required(ErrorMessage = "Zły login.")]
    [StringLength(20), MinLength(3)]
    [RegularExpression(@"^[a-zA-Z0-9]*$", ErrorMessage = "Special characters are not allowed.")]
    public string Login { get; set; }

    [Required(ErrorMessage = "Złe hasło.")]
    [StringLength(20, MinimumLength = 3)]
    [DataType(DataType.Password)]
    [Display(Name = "Hasło")]
    public string Password { get; set; }

    public virtual List<Entry> CreatedEntries { get; set; } // napisane aktualności przez danego admina
}

条目：

public class Entry
{
    [Key, ScaffoldColumn(false)]
    public int Id { get; set; }

    [StringLength(200, MinimumLength = 2)]
    [DataType(DataType.Text)]
    [Display(Name = "Tytuł")]
    public string Title { get; set; }

    [Required, StringLength(2000), MinLength(3)]
    [Display(Name = "Treść")]
    [UIHint("tinymce_jquery_full"), AllowHtml]
    public string Text { get; set; }

    public virtual Admin Admin { get; set; }
}

您可能知道往哪里去，因为这个问题是计算器......经典。

You probably know where it is going, since this problem is... "classic" on stackoverflow.

在控制器我想一个对象绑定到另一个：

In the Controller I want to bind one object to another:

entry.Admin = repAdmins.GetAdmin(User.Identity.Name);

repEntries.AddEntry(entry);

在存储库：

public void AddEntry(Entry entry)
    {
        db.Entries.Add(entry);
        db.SaveChanges();
    }

当然，我不能这样做，因为出名，这是每一个仓库有不同的数据库环境的结果一个实体对象不能被IEntityChangeTracker的多个实例引用。

Of course I can't do that, because of famous "An entity object cannot be referenced by multiple instances of IEntityChangeTracker", which is a result of having separate database contexts in each repository.

当我在寻找我已经知道可能解决它是使用一个共同的背景下，最好的方式解决。然后我发现单位工作模式。但真正的问题开始的时候这里的。

When I was searching for a solution I already knew that probably the best way to solve it is to use one common context. And then I discovered Unit Of Work pattern. But here's when the real problems starts.

1. 在很多网站的解决方案，这是一个有点不同。


2. 的库必须有共同的通用接口（我不想用了，因为我并不需要对每个实体的每个CRUD操作，再加上有时我需要有额外的方法，如IfExists等。 ）


3. 在几个网站，我读过，并不需要这整个抽象，抽象以来已经提供了实体框架和UOW中的DbContext执行（知道是什么意思）


4. 工作模式（至少从互联网上的例子）的单位似乎对我来说是真正的痛苦...

我需要一些指导......我学习ASP.NET MVC只待了一年。对我来说，这似乎就像是一个的形式对内容的胜利。因为... 我只是需要的是一个对象绑定到另一个。我开始认为这是更好的时候我只是有一个控制器中的上下文对象，我也没必要建埃菲尔铁塔达到上述提到什么的：\\但是我喜欢知识库的想法......

I need some guidance... I learn ASP.NET MVC for only a year. For me it seems like it's a "triumph of form over content". Because... What I simply need is to bind one object to another. I'm starting to think that it was better when I simply had a context object in the Controller and I didn't need to build Eiffel Tower to achieve what's mentioned above :\ However I like idea of repositories...

对不起，我的英语...

Sorry for my English...

推荐答案

下面的示例演示如何使用多个系统信息库中相同的上下文。为了简化它，我没有使用接口和我也没有使用容器注入的依赖关系。

The following example shows how to use the same context within multiple repositories. To simplify it, I did not use interfaces and nor did I use a container to inject dependencies.

Controller类：

Controller class:

public class HomeController : Controller
{
    Context context;
    AdminRepository adminRepository;
    EntryRepository entryRepository;

    public HomeController()
    {
        context = new Context();
        adminRepository = new AdminRepository(context);
        entryRepository = new EntryRepository(context);
    }
    // GET: Home
    public ActionResult Index()
    {
        string login = "MyLogin";
        Admin admin = adminRepository.GetAdmin(login);
        Entry entry = new Entry() { Admin = admin};
        entryRepository.AddEntry(entry);
        return View(entry);
    }
}

库：

public class AdminRepository
{
    Context context;
    public AdminRepository(Context context)
    {
        this.context = context;

        // This seeds the database
        Admin admin = new Admin() { Login = "MyLogin" };
        this.context.Admins.Add(admin);
        this.context.SaveChanges();
    }

    public Admin GetAdmin(string login)
    {
        return context.Admins.Where(a => a.Login == login).FirstOrDefault();
    }
}

public class EntryRepository
{
    Context context;
    public EntryRepository(Context context)
    {
        this.context = context;
    }

    public void AddEntry(Entry entry){
        context.Entrys.Add(entry);
        context.SaveChanges();
    }
}

Context类：

Context class:

public class Context : DbContext
{
    public Context()
    {
        Database.SetInitializer<Context>(new DropCreateDatabaseAlways<Context>());
        Database.Initialize(true);
    }

    public DbSet<Admin> Admins { get; set; }
    public DbSet<Entry> Entrys { get; set; }
}

改款车型：

public class Admin
{
    public int Id { get; set; }
    public string Login { get; set; }

}

public class Entry
{
    public int Id { get; set; }
    public virtual Admin Admin { get; set; }
}

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