如何在构造函数中注入多个依赖项？

Question

我正在进行单元测试。我有一个依赖于多个存储库的控制器（意味着有多个依赖项）。

以下是控制器的代码： -

public class TestController : BaseController
{
  //Declaring dependencies 
   private IProductService _productService;
   private IStudenctService _studentService;
   private ITeacherService _teacherService;
   private IClassService _classService;
   private ITaxService _taxService;
   private ICategoryService _categoryService;
   private ISchoolService _schoolService;
  //Constructor calling…
   public TestController ()
   {

   }

   public TestController (IProductService productService)
   {
       this._ productService = productService;
   }
   public TestController (IStudenctService studenctService)
   {
       this._ studentService = studenctService;
   }
   public TestController (ITeacherService teacherService)
   {
       this._ teacherService = teacherService;
   }
   public TestController (IClassService classService)
   {
       this._ classService = classService;
   }
   public TestController (ITaxService taxService)
   {
       this._ taxService = taxService;
   }
   public TestController (ICategoryService categoryService)
   {
       this._ categoryService = categoryService;
   }
   public TestController (ISchoolService schoolService)
   {
       this._ schoolService = schoolService;
   }
  public TestController (ISchoolService schoolService, ICategoryService categoryService)
   {
       this._ schoolService = schoolService;
       this._ categoryService = categoryService;
   }
   public TestController (ISchoolService schoolService, ICategoryService categoryService, ITaxService taxService, IClassService classService)       {
       this._ schoolService = schoolService;
       this._ categoryService = categoryService;
       this._ taxService = taxService;
       this._ classService = classService;
   }
}

在上面的代码中，我为每个依赖项创建了单独的构造函数。其中有2个构造函数采用多个参数（依赖arg）。

通过这个我的单元测试方法运行良好。但是当我运行应用程序时它会给我以下错误： -

  

呃 - 哦，出了点问题！错误代码：500

但是当我只调用一个参数构造函数然后它的工作时。任何人都可以让我知道这里有什么问题吗？在多个依赖项的情况下应该怎么做？

Answer 1

如果这些是您的类的依赖项，那么您应该有一个构造函数，它将所有依赖项作为参数。

换句话说，如果没有所有依赖项，则无法实例化为有效状态。它们不是可选的，它们是依赖项。

我会从采用这种方法开始，然后问一个单独的问题，如果你的应用程序仍然会抛出错误。