Question

您好我是C＃的新手，可以与任何人的帮助，如何发现问题所在。我一直收到一条错误消息，指出在＆＃39; _parcelService＆＃39;行下检测到无法访问的代码在底部。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using ABC.Data;
using ABC.Services;
using ABC.Services.Service;
namespace ABC.Controllers
{
    public class AdminController : Controller
    {
        private ParcelService _parcelService;
        public AdminController()
        {
            _parcelService = new ParcelService();
        }

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

        [HttpGet]
        public ActionResult AddParcel()
        {
            return View();
        }
        [HttpPost]
        public ActionResult AddParcel(ParcelDetail parcel)
        {
            return View();

            {
                _parcelService.AddParcel(parcel);

                return RedirectToAction("Parcels",
                    new { TrackingID = parcel.TrackingID, controller = "Parcel" });
            }
         }

     }
 }

Answer 1

在这一行，你已经从行动中返回了一个结果：

return View();

从函数返回的语句之后不能有任何内容。所以摆脱这条线：

[HttpPost]
public ActionResult AddParcel(ParcelDetail parcel)
{
    _parcelService.AddParcel(parcel);

    return RedirectToAction("Parcels",
        new { TrackingID = parcel.TrackingID, controller = "Parcel" });
}

或者您可能想要应用一些逻辑，如果模型的验证失败，则会重新呈现相同的视图，否则会调用您的后端服务并重定向：

[HttpPost]
public ActionResult AddParcel(ParcelDetail parcel)
{
    if (!ModelState.IsValid)
    {
        // The model that was passed to this action was not valid
        // => Redisplay the same view so that the user can correct
        // the errors
        return View();
    }

    // At this stage we know that the model is valid and we can submit it
    // for processing
    _parcelService.AddParcel(parcel);

    // redirect to a different action by returning the corresponding result
    return RedirectToAction(
        "Parcels",
        new { TrackingID = parcel.TrackingID, controller = "Parcel" }
    );
}

Answer 2

你得到的错误是自我解释。以下

return View()

你返回一个视图。因此，此后的每个代码都无法访问。我认为您的代码的正确版本如下：

[HttpPost]
public ActionResult AddParcel(ParcelDetail parcel)
{
    // Here you add the parcel
     _parcelService.AddParcel(parcel);

    // Then you make a redirect to a view that are visible all the parcels.
    return RedirectToAction("Parcels",
    new  
    { 
        TrackingID = parcel.TrackingID, 
        controller = "Parcel" 
    });
}

在你调用AddParcel强制执行某些验证之前会很好，比如你的对象是否有效（检查Darin'n答案）。如果您的POST parcel通过了这些验证，那么您应该致电AddParcel。否则，您应该向客户返回她发布的错误对象并解释为什么这是错误的。

Answer 3

return View();  // problem here

{
 _parcelService.AddParcel(parcel);

 return RedirectToAction("Parcels",
                new { TrackingID = parcel.TrackingID, controller = "Parcel" });
}

这就是你的问题所在。在你的逻辑（代码）被击中之前你正在返回。你还有2个回报......

因为您有return RedirectToAction，所以您可以删除return View()

所以解决方案：

[HttpPost]
    public ActionResult AddParcel(ParcelDetail parcel)
    {
        // return View();  or just delete it.. since there is really no point to keep it commented out.

        {
            _parcelService.AddParcel(parcel);

            return RedirectToAction("Parcels",
                new { TrackingID = parcel.TrackingID, controller = "Parcel" });
        }
     }

无法访问的代码检测到c＃beginner

3 个答案: