Issue

You have a database table with a primary key made up of two columns. This is also called a composite key.

You want to model this in your class using the DataAnnotations Attributes.

The solution

As of the later .Net Core, (I think 6 or above) you need to:

Reference the NuGet Package

Looks something like this in your solution file

<ItemGroup>
  <PackageReference Include="Microsoft.EntityFrameworkCore" Version="8.0.12" />
</ItemGroup>

Then create you class as follows

[Table("MyTable")]
[PrimaryKey(nameof(PKOneId), nameof(PKTwoId))]
public class MyTableDto
{
    public required int PKOneId { get; set; }
    public required int PKTwoId{ get; set; }
    public bool IsActive { get; set; }
}