C# 强制转换和合并两个相同接口但不同类型的列表

我得到了两个使用相同接口的实体。我想将从实体框架获得的两个结果合并到一个

IKurs

：

public async Task<IEnumerable<IKurs<ITeacherToCourse<IAdditionalTeacherData>, IAdditionalTeacherData>>> GetCourses(bool takeXtr)
{
    IEnumerable<IKurs<ITeacherToCourse<IAdditionalTeacherData>, IAdditionalTeacherData>> result  = new List<IKurs<ITeacherToCourse<IAdditionalTeacherData>, IAdditionalTeacherData>>();
    if (takeXtr)
        using (var context = new Context())
        {
            var courses = context.XtrCourses.Include(x=>x.TeachersToCourses).Where(_someCourseFilterForAgs);
            result.Concat(await courses.ToListAsync()).Cast<IKurs<ITeacherToCourse<IAdditionalTeacherData>, IAdditionalTeacherData>>();
        }

    using (var context = new Context())
    {
        var courses = context.AgsCourses.Include(x=>x.TeachersToCourses).Where(_someCourseFilterForAgs);
        result.Concat(await courses.ToListAsync()).Cast<IKurs<ITeacherToCourse<IAdditionalTeacherData>, IAdditionalTeacherData>>();
    }
    return result;
}

类

agsteachertocurse

和

xtrtachertocurse

都实现

iteachertocurse

类

agsteachertocurse

和

xtrtachertocurse

都实现

iteachertocurse

如何将它们合并到一个列表中

---

实际上，两个课程列表都来自不同的背景。这就是为什么我在

GetCourses（）

中两次启动上下文。

不需要强制转换，您可以将任何

ikur

添加到列表中

    interface IMyclass{}

    class MyType1 : IMyclass {}

    class MyType2 : IMyclass {}

    public class SomeClass
    {
        private List<IMyclass> MyList = new List<IMyclass>();

        public void DoSomething()
        {
            MyList.AddRange(new List<IMyclass> { new MyType1(), new MyType1() });
            MyList.AddRange(new List<IMyclass> { new MyType2(), new MyType2() });
        }
    }

接口IMyclass{}
类MyType1:IMyclass{}
类MyType2:IMyclass{}
公共类
{
私有列表MyList=新列表（）；
公共无效剂量测定法（）
{
AddRange（新列表{new MyType1（），new MyType1（）}）；
AddRange（新列表{new MyType2（），new MyType2（）}）；
}
}

主要问题之一是

interface ITeacherToCourse<T> where T : IAdditionalTeacherData
{
    int Nr { get; set; }
    T AdditionalTeacherData { get; set; }
}

class XtrTeacherToCourse : ITeacherToCourse<XtrAdditionalTeacherData>
{
    public int Nr { get; set; }
    public XtrAdditionalTeacherData AdditionalTeacherData { get; set; }
}

class AgsTeacherToCourse : ITeacherToCourse<AgsAdditionalTeacherData>
{
    public int Nr { get; set; }
    public AgsAdditionalTeacherData AdditionalTeacherData { get; set; }
}

如果您不想设置

AdditionalTeacherData

属性，那么您可以声明如下接口

interface ITeacherToCourse<out T> where T : IAdditionalTeacherData
{
    int Nr { get; set; }
    T AdditionalTeacherData { get; }
}

对于集合，它是相同的

总接口声明

interface IAdditionalTeacherData
{

}

interface ITeacherToCourse<out T> where T : IAdditionalTeacherData
{
    int Nr { get; set; }
    T AdditionalTeacherData { get; }
}

interface IKurs<out TTeacherToCourse, out TAdditionalTeacherData>
    where TTeacherToCourse : ITeacherToCourse<TAdditionalTeacherData>
    where TAdditionalTeacherData : IAdditionalTeacherData
{
    int Nr { get; set; }
    IEnumerable<TTeacherToCourse> TeachersToCourses { get; }
}

接口IAdditionalTeacherData
{
}
接口ITeacherTourCourse，其中T:IAdditionalTeacherData
{
int Nr{get；set；}
T额外的教师数据{get；}
}
接口IKurs
TTeachertocurse的位置：ITeachertocurse
其中TadeditionalTeacherData:IAdeditionalTeacherData
{
int Nr{get；set；}
IEnumerable TeachersToCourses{get；}
}

以及实现类

class XtrAdditionalTeacherData : IAdditionalTeacherData
{

}

class XtrTeacherToCourse : ITeacherToCourse<XtrAdditionalTeacherData>
{
    public int Nr { get; set; }
    public XtrAdditionalTeacherData AdditionalTeacherData { get; set; }
}

class XtrCourse : IKurs<XtrTeacherToCourse, XtrAdditionalTeacherData>
{
    public int Nr { get; set; }
    public ICollection<XtrTeacherToCourse> TeachersToCourses { get; set; }
    // explicit implementation
    IEnumerable<XtrTeacherToCourse> IKurs<XtrTeacherToCourse, XtrAdditionalTeacherData>.TeachersToCourses => TeachersToCourses;
}

class AgsAdditionalTeacherData : IAdditionalTeacherData
{

}

class AgsTeacherToCourse : ITeacherToCourse<AgsAdditionalTeacherData>
{
    public int Nr { get; set; }
    public AgsAdditionalTeacherData AdditionalTeacherData { get; set; }
}

class AgsCourse : IKurs<AgsTeacherToCourse, AgsAdditionalTeacherData>
{
    public int Nr { get; set; }
    public ICollection<AgsTeacherToCourse> TeachersToCourses { get; set; }
    // explicit implementation
    IEnumerable<AgsTeacherToCourse> IKurs<AgsTeacherToCourse, AgsAdditionalTeacherData>.TeachersToCourses => TeachersToCourses;
}

class XtraditionalTeacherData:IAditionalTeacherData
{
}
类XtrTeacherToCourse:ITeacherToCourse
{
公共int Nr{get；set；}
public XtraditionalTeacherData AdditionalTeacherData{get；set；}
}
第XTR类课程：IKurs
{
公共int Nr{get；set；}
公共ICollection教师课程{get；set；}
//显式实现
IEnumerable IKurs.TeachersToCourses=>teacherstourses；
}
类别AgsAdditionalTeacherData:IAdditionalTeacherData
{
}
AgsTeacherToCourse类课程：ItacherToCourse
{
公共int Nr{get；set；}
公共AgsAdditionalTeacherData附加TeacherData{get；set；}
}
分类：IKurs
{
公共int Nr{get；set；}
公共ICollection教师课程{get；set；}
//显式实现
IEnumerable IKurs.TeachersToCourses=>teacherstourses；
}

现在我们可以添加实例，而无需任何强制转换

var collection = new List<IKurs<ITeacherToCourse<IAdditionalTeacherData>, IAdditionalTeacherData>>();

collection.Add(new XtrCourse());
collection.Add(new AgsCourse());

var集合=新列表（）；
添加（新的XtrCourse（））；
添加（新的agscorse（））；

尝试使用

result.AddRange（wait courses.ToListAsync（））但这让我的编译器大哭：（
参数类型列表不可分配给parametertype IEnumerable
-我想我首先需要转换完整的结构，然后？@MatthiasBurger您的类型一定有问题。我必须承认我对您复杂的类型定义感到困惑，但只要您从编译器中获得此错误，转换将无法工作。错误基本上告诉您，强制转换将不起作用。我仍然不知道确切原因，但鲁福爵士已经发现了问题。我需要研究为什么需要在我的界面中使用
out
。但谢谢您的帮助：）-是的，结构令人困惑。你是对的-这不是我的数据库设计：DWow.Perfect.
out
就是问题所在。谢谢你的帮助：）
interface IAdditionalTeacherData
{

}

interface ITeacherToCourse<out T> where T : IAdditionalTeacherData
{
    int Nr { get; set; }
    T AdditionalTeacherData { get; }
}

interface IKurs<out TTeacherToCourse, out TAdditionalTeacherData>
    where TTeacherToCourse : ITeacherToCourse<TAdditionalTeacherData>
    where TAdditionalTeacherData : IAdditionalTeacherData
{
    int Nr { get; set; }
    IEnumerable<TTeacherToCourse> TeachersToCourses { get; }
}

class XtrAdditionalTeacherData : IAdditionalTeacherData
{

}

class XtrTeacherToCourse : ITeacherToCourse<XtrAdditionalTeacherData>
{
    public int Nr { get; set; }
    public XtrAdditionalTeacherData AdditionalTeacherData { get; set; }
}

class XtrCourse : IKurs<XtrTeacherToCourse, XtrAdditionalTeacherData>
{
    public int Nr { get; set; }
    public ICollection<XtrTeacherToCourse> TeachersToCourses { get; set; }
    // explicit implementation
    IEnumerable<XtrTeacherToCourse> IKurs<XtrTeacherToCourse, XtrAdditionalTeacherData>.TeachersToCourses => TeachersToCourses;
}

class AgsAdditionalTeacherData : IAdditionalTeacherData
{

}

class AgsTeacherToCourse : ITeacherToCourse<AgsAdditionalTeacherData>
{
    public int Nr { get; set; }
    public AgsAdditionalTeacherData AdditionalTeacherData { get; set; }
}

class AgsCourse : IKurs<AgsTeacherToCourse, AgsAdditionalTeacherData>
{
    public int Nr { get; set; }
    public ICollection<AgsTeacherToCourse> TeachersToCourses { get; set; }
    // explicit implementation
    IEnumerable<AgsTeacherToCourse> IKurs<AgsTeacherToCourse, AgsAdditionalTeacherData>.TeachersToCourses => TeachersToCourses;
}

var collection = new List<IKurs<ITeacherToCourse<IAdditionalTeacherData>, IAdditionalTeacherData>>();

collection.Add(new XtrCourse());
collection.Add(new AgsCourse());