C# - 如何传递具有“this”类类型的泛型类型

Question

I have a User class that has a GetQueryable method. Another method, Select() , calls GetQueryable() . I want to use the Select method without passing the type User to the Select method, because I have it in this but I can't use it.

Type type = this.GetType();

???

var x = this.GetQueryable< ??? >().ToList();

class Program
{
    static void Main(string[] args)
    {
        var acc = new User();
        acc.Select();
    }
}

public partial class User
{
    public DB_Test001Entities context;

    public User()
    {
        context = new DB_Test001Entities();
    }
    public void Select()
    {  
        Type type = this.GetType();
        var x = this.GetQueryable< **???** >().ToList();
    }

    public IQueryable<TEntity> GetQueryable<TEntity>(List<string> includes = null) where TEntity : class
    {
        IQueryable<TEntity> items = context.Set<TEntity>();

        if (includes != null && includes.Any())
            includes.Where(i => i != null).ToList().ForEach(i => { items = items.Include(i); });

        return items;
    }
}

Answer 1

You can do it using reflection. The following sample works smoothly. In program you can use Clerk or Manager , just any instance derived from User to call Select . You can improve your program with this.

    class Clerk : User { }

    class Manager : User { }

    internal class User
    {
        public User() { }

        public string Name { get; set; }

        public void Select()
        {
            var list = new List<string>() {"Jack", "Martin"};
            Type thisType = GetType();
            MethodInfo method = thisType.GetMethod("GetQueryable").MakeGenericMethod(thisType);
            method.Invoke(this, new object[] {list});
        }

        public IQueryable<TEntity> GetQueryable<TEntity>(List<string> includes = null) where TEntity : User, new()
        {
            if(includes != null)
            {
                Console.WriteLine(typeof(TEntity));
                var entity = new List<TEntity>(includes.Count);
                entity.AddRange(includes.Select(item => new TEntity {Name = item}));
                return entity.AsQueryable();
            }
            return null;
        }
    }

    class Program
    {
        static void Main()
        {
            User usr = new Manager();
            usr.Select();
        }
    }