在ASP.NET Core MVC模型中访问_context [英] Access _context in an ASP.NET Core MVC Model

问题描述

我正在尝试从ASP.NET Core 1.0 MVC项目中的模型内与数据库进行交互. 脚手架已被用来从模型中创建控制器和视图.

I'm trying to interact with the database from within a Model in an ASP.NET Core 1.0 MVC project. Scaffolding has been used to create Controllers and views from the Models.

理想情况下，我想像使用_context在控制器中一样访问它，但是我找不到这样做的方法.

Ideally I would like to access it like I would in a controller with the _context but I failed finding a way to do so.

我还尝试根据模型创建新连接:

I also tried to create a new connection from the model:

using (var context = new ApplicationDbContext()){
    // Code here
}

但是ApplicationDbContext构造函数需要选项参数，例如我无法从配置中检索到的默认连接字符串.

But the ApplicationDbContext constructor requires options arguments like the default connection string which I failed retrieving from the config.

Public ApplicationDbContext(DbContextOptions options) : base(options) {
}

我的猜测是我误解了一些非常基本的东西，因为这应该很容易做到.

My guess is that I misunderstand something very basic because this should be easy to do.

有什么想法吗?

推荐答案

正如其他人告诉您的那样，方法是使用依赖项注入.

As others have told you, the way is use dependency injection.

这是一个真实的示例(使用postgresql):

Here is a real example (using postgresql):

Startup.cs:

Startup.cs:

    public void ConfigureServices(IServiceCollection services)
    {
        ...

        #region PostgreSQL
        var sqlConnectionString = Configuration.GetConnectionString("your connection string name");

        // Use a PostgreSQL database
        services.AddDbContext<ApplicationDbContext>(options =>
            options.UseNpgsql(
                sqlConnectionString,
                b => b.MigrationsAssembly("Your.Assembly.Name")
            )
        );
        #endregion

        ...
    }

在您的控制器中(例如api控制器):

In your controller (example of an api controller):

[Produces("application/json")]
[Route("api/MyController")]
public class MyController : Controller
{

    private readonly ApplicationDbContext _context;

    public DatasourceDataController(ApplicationDbContext context)
    {
        _context = context;
    }

    [HttpGet()]
    public async Task<IActionResult> DoSometing()
    {
        ...
        await _context.(...);
        ...
    }
}

这里有一个完整的示例(您可以向下滚动到创建数据库上下文"):

Here you have a full example (you can scroll down to "Create the Database Context"): https://docs.microsoft.com/en-us/aspnet/core/data/ef-mvc/intro

希望有帮助.

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