Upload file in ASP.NET Core MVC - get error "The name 'Server' does not exist in the current context"

Question

I wrote code to upload a file in ASP.NET MVC but Server and HttpPostedFileBase are undefined in my controller.

My UploadFile.cshtml is as follows:

@{
   ViewBag.Title = "UploadFile";
}

<h2>UploadFile</h2>

@using (Html.BeginForm("UploadFile", "Upload", FormMethod.Post, new { enctype = "multipart/form-data" }))
{
    <div>
       @Html.TextBox("file", "", new {  type= "file"}) <br />
       <input type="submit" value="Upload" />
       @ViewBag.Message
    </div>
}

And this is the UploadController.cs:

using Microsoft.AspNetCore.Mvc;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Web;

namespace WebApplication4.Controllers
{
    public class UploadController : Controller
     {
        // GET: Upload
        public ActionResult Index()
        {
           return View();
        }

        [HttpGet]
        public ActionResult UploadFile()
        {
            return View();
        }

        [HttpPost]
        public ActionResult UploadFile(HttpPostedFileBase file)
        {
            if (file is null)
            {
                throw new ArgumentNullException(nameof(file));
            }

            try
            {
               if (file.ContentLength > 0)
               {
                   string _FileName = Path.GetFileName(file.FileName);
                   string _path = Path.Combine(Server.MapPath("~/UploadedFiles"), _FileName);
                   file.SaveAs(_path);
                }

                ViewBag.Message = "File Uploaded Successfully!!";

                return View();
             }
             catch
             {
                 ViewBag.Message = "File upload failed!!";
                 return View();
             }
         }
    }
}

When I run the code, I get these errors:

The type or namespace name 'HttpPostedFileBase' could not be found (are you missing a using directive or an assembly reference?)

The name 'Server' does not exist in the current context

Answer 1

The best way to get path of root folder is to use IWebHostEnviroment and for upload file type use IFormFile like this:

public class HomeController : Controller
{
    private readonly IWebHostEnvironment _WebHost;

    public HomeController(IWebHostEnvironment WebHost)
    {
        _WebHost = WebHost;
    }

    // GET: Upload
    public ActionResult Index()
    {
        return View();
    }

    [HttpGet]
    public ActionResult UploadFile()
    {
        return View();
    }

    [HttpPost]
    public ActionResult UploadFile(IFormFile file)
    {
        if (file is null)
        {
            throw new ArgumentNullException(nameof(file));
        }
        try
        {

            if (file.Length > 0)
            {
                string _FileName = Path.GetFileName(file.FileName);
                string _path = Path.Combine(_WebHost.WebRootPath, "/UploadedFiles", _FileName);
                // Save file
                using var stream = System.IO.File.Create(_path);
                file.CopyTo(stream);
            }
            ViewBag.Message = "File Uploaded Successfully!!";
            return View();
        }
        catch
        {
            ViewBag.Message = "File upload failed!!";
            return View();
        }
    }
}