将参数传递给继承自DbContext的类 [英] Pass parameter to class which inherits from DbContext

问题描述

我的应用程序是一个 ASP.NET Core 1.0 Web API 。我使用实体框架。

我不会更改 CommandTimeout 这样：

  public class MyDbContext：DbContext 
 {
 private const int Timeout = 180; 
 
 public MyDbContext（DbContextOptions options）：base（options）
 {
 this.Database.SetCommandTimeout（Timeout）; 
} 
} 
  

如果超时在我的课程中定义。

但是，我想要具有我的超时值我的 appsettings.json 文件如下：

 DbContextSettings ：{
超时：180
} 
  

现在有两种设置 CommandTimeout 的方法：

1. 通过 CommandTimeOutInSeconds 作为构造函数的参数。


2. 从 appsettings.json 中获取值我的课程的构造函数

我不知道如何实现其中一种方式。

这可能吗？还是有任何已知的解决方法？

修改

Iam从不真正地初始化 MyDbContext 。我在 ConfigureServices 在启动类中这样做：

  services.AddDbContext< MyDbContext>（db => db.UseSqlServer（secret））; 
  

编辑2

  public class SomeRepository 
 {
 
私人MyDbContext上下文; 
 
 public SomeRepository（MyDbContext myContext）
 {
 this.context = myContext; 
} 
 
 public Person SomeMethodCalledByController（）{
 return myContext.SomeTableWhichContainsPersons.FirstOrDefault（person => person.name ==Bob）; 
} 
} 
  

类 SomeRepository 从来没有被我初始化。 Iam通过依赖注入在启动中执行此操作，如下所示：

  services.AddTransient< SomeRepository>（）; 
  

该类从上面了解 MyDbContext 显示行：

  services.AddDbContext< MyDbContext>（db => db.UseSqlServer（secret））; 
  

所以我从来没有传递一个 MyDbContext 直接到我使用数据库的任何类。

解决方案

你可以将这个超时传递给你的构造函数： >



  public MyDbContext（DbContextOptions options，int timeout）：base（options）
 {
 Timeout = timeout; 
 this.Database.SetCommandTimeout（Timeout）; 
} 
  

这里是一个如何从App settings.json读取设置的示例 csharpcorner

编辑

  public MyDbContext（DbContextOptions options）：base（options）
 {
 int timeout = //从appsettings.json返回超时设置
 this.Database.SetCommandTimeout（Timeout）; 
} 
  

你可以尝试这样做，你读你的appsettings.json您的构造函数内。

My application is an ASP.NET Core 1.0 Web API. I am using Entity framework.

I wan't to change the CommandTimeout like this:

public class MyDbContext: DbContext
{
   private const int Timeout = 180;

   public MyDbContext(DbContextOptions options): base(options)
   {
       this.Database.SetCommandTimeout(Timeout);
   }
}

this works if Timeout is defined in my class.

However, I would like to have the value of my Timeout inside my appsettings.json file like this:

  "DbContextSettings": {
    "Timeout": "180"
  }

so there are two ways to set the CommandTimeout now:

1. Pass the CommandTimeOutInSeconds as a parameter to the constructor.
2. Get the value out of appsettings.json inside the constructor of my class

I don't know how to achieve one of the ways.

Is this possible? or is there any known workaround?

Edit

Iam never really Initailizing MyDbContext. I do this in ConfigureServices in the Startup class like this:

services.AddDbContext<MyDbContext>(db => db.UseSqlServer("secret"));

Edit 2

@dennisanberlin so let's say I have a controller calling the following method:

public class SomeRepository
{

  private MyDbContext context;

  public SomeRepository(MyDbContext myContext)
  {
     this.context = myContext;
  }

  public Person SomeMethodCalledByController(){
     return myContext.SomeTableWhichContainsPersons.FirstOrDefault(person => person.name == "Bob");
  }
}

The class SomeRepository is never getting initialized by me. Iam doing this via dependency injection in the startup like this:

services.AddTransient<SomeRepository>();

The class knows about MyDbContext from the above shown line:

services.AddDbContext<MyDbContext>(db => db.UseSqlServer("secret"));

Therefore I never pass an object of MyDbContext directly to any of my classes working with the database.

解决方案

You can pass the timeout to your constructor like this:

public MyDbContext(DbContextOptions options, int timeout): base(options)
   {
       Timeout = timeout;
       this.Database.SetCommandTimeout(Timeout);
   }

And here is an example on how to read settings from your App settings.json csharpcorner

EDIT

public MyDbContext(DbContextOptions options): base(options)
   {
       int timeout = //return timeout setting from appsettings.json
       this.Database.SetCommandTimeout(Timeout);
   }

You can try to do it that way, that you read your appsettings.json inside your constructor.

这篇关于将参数传递给继承自DbContext的类的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！