访问继承的泛型类的属性

Question

Based on this topic: C# - Multiple generic types in one list

Please consider this code:

public abstract class Metadata
{
}

public class Metadata<T> : Metadata
{
    public string Name {set; get;}
}

public class MetaDataCollection
{
    public void DoSomeThing()
    {
        List<Metadata> metadataObjects = new List<Metadata>
        {
            new Metadata<int>() { Name = "Name 1"},
            new Metadata<bool>() { Name = "Name 2"},
            new Metadata<double>() { Name = "Name 3"},
        };

        foreach(vat item in metadataObjects)
        {
            item.Name ??????
        }
    }
}

in above code how I can access to Name property?

Thanks

EDIT 1)

Thanks @BWA. But I have a generic property:

public class Metadata<T> : Metadata
{
    public override string Name {set; get;}

    public List<T> Some {set; get;} <-----
}

and I can't declare it in base abstract class. For that property what I can do?

Answer 1

Your code doesn,t compile.

Metadata, Metadata<T>, Metadata<int> ...

Each are different type. Generic types isn't inheritance. You cann't do this in this way.

You can do in this way:

using System.Collections.Generic;

public abstract class Metadata
{
    public abstract string Name { set; get; }
}

public class Metadata<T> : Metadata
{
    public override string Name {set; get;}
}

public class MetaDataCollection
{
    public void DoSomeThing()
    {
        List<Metadata> metadataObjects = new List<Metadata>
        {
            new Metadata<int>() { Name = "Name 1"},
            new Metadata<bool>() { Name = "Name 2"},
            new Metadata<double>() { Name = "Name 3"},
        };

        foreach(Metadata item in metadataObjects)
        {
            string s = item.Name;
        }
    }
}

At first Metadata<T> must inherit from Metadata . And then inheritance can work.

Answer 2

Right now, Metadata and Metadata are unrelated. They have no inheritance relationship, just similar names.

One option is to pull the Name property to Metadata and have Metadata inherit from it:

public abstract class Metadata
{
    public string Name {set; get;}
}

public class Metadata<T>:Metadata
{
    //public string Name {set; get;}
}

The other option is to convert Metadata to an interface with a Name property :

public interface IMetadata
{
    string Name {set; get;}
}

public class Metadata<T>:IMetadata
{
    public string Name {set; get;}
}

Change the test code to use the correct base class, eg :

{
    var metadataObjects = new List<Metadata>
    {
        new Metadata<int>() { Name = "Name 1"},
        new Metadata<bool>() { Name = "Name 2"},
        new Metadata<double>() { Name = "Name 3"},
    };

or

    var metadataObjects = new List<IMetadata>
    {
        new Metadata<int>() { Name = "Name 1"},
        new Metadata<bool>() { Name = "Name 2"},
        new Metadata<double>() { Name = "Name 3"},
    };

In both cases, the loop remains the same :

    foreach(var item in metadataObjects)
    {
        Console.WriteLine(item.Name);
    }

Answer 3

i don't if this is what you want but its gonna give you the result you ask.

public class Metadata
{
   public Type type { get; set; }
   public string Name { set; get; }
}

public class MetaDataCollection
{
   public void DoSomeThing()
   {
      List<Metadata> metadataObjects = new List<Metadata>
      {
         new Metadata() { Name = "Name 1", type = typeof(int)},
         new Metadata() { Name = "Name 2", type = typeof(bool)},
         new Metadata() { Name = "Name 3", type = typeof(double)},
      };

      foreach (Metadata item in metadataObjects)
      {
         item.Name..
      }
   }
}