When I try to get data from data for edit page it's showing me the following error:

So I am building a website where I want to implement a edit banner form when the User can Edit his banner data.

And here is where the problem I raise, when I run the code, it return always as null.

Here is my controller:

[HttpGet]
public ActionResult EditBanner(int id)
{
    var abd = (from a in _db.Banner
                where id == a.BannerId
                select a).FirstOrDefault();

    return View(abd);
}

[HttpPost]
public ActionResult UpdateBannerDatas(BannerViewModels bnrupdate)
{
    var bnrdata = _db.Banner.Where(x => x.BannerId == bnrupdate.BannerId).FirstOrDefault();
    if (bnrdata != null)
    {
        bnrdata.BannerTitle = bnrupdate.BannerTitle;
        bnrdata.BannerUrl = bnrupdate.BannerUrl;
        bnrdata.BannerIndex = bnrupdate.BannerIndex;
        bnrdata.BannerDescription = bnrupdate.BannerDescription;
        bnrdata.BannerIndex = bnrupdate.BannerIndex;

        _db.SaveChanges();

    }
    return Redirect("BannerDetails");
}

Here is my viewmodel:

using Microsoft.AspNetCore.Http;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using SZGMC.Web.Models;

namespace SZGMC.Web.Areas.Admin.ViewModels
{
    public class BannerViewModels
    {
        public int BannerId { get; set; }
        public string BannerTitle { get; set; }
        public string BannerDescription { get; set; }
        public string BannerImg { get; set; }
        public IFormFile BannerImg1 { get; set; }
        public string BannerUrl { get; set; }
        public string BannerIndex { get; set; }
        public int? BMasterId { get; set; }
        public byte? IsDeleted { get; set; }

        public virtual BannerMaster BMaster { get; set; }
    }
}

Here is my model:

using System;
using System.Collections.Generic;

// Code scaffolded by EF Core assumes nullable reference types (NRTs) are not used or disabled.
// If you have enabled NRTs for your project, then un-comment the following line:
// #nullable disable

namespace SZGMC.Web.Models
{
    public partial class Banner
    {
        public int BannerId { get; set; }
        public string BannerTitle { get; set; }
        public string BannerDescription { get; set; }
        public string BannerImg { get; set; }
        public string BannerUrl { get; set; }
        public string BannerIndex { get; set; }
        public int? BMasterId { get; set; }
        public byte? IsDeleted { get; set; }

        public virtual BannerMaster BMaster { get; set; }
    }
}

Here is my view:

<form asp-controller="Home" asp-action="UpdateBannerDatas" enctype="multipart/form-data" method="post">

    <div id="main-content">
        <div >
            <!-- Page header section  -->
            <div >
                <div >
                    <div >
                        <h1>Hi, Welcomeback!</h1>
                        <span>You can edit banner here</span>
                    </div>
                    <div >
                        <div >
                            <div >
                                <a asp-action="BannerDetails" >Banner List</a>
                            </div>
                        </div>
                    </div>
                </div>
            </div>
            <div >
                <div >
                    <div >
                        <div >
                            <div >
                                <h2><strong>Enter Banner Details</strong></h2>
                            </div>
                            <br />
                            <input asp-for="BannerId" type="hidden" />
                            <div >
                                <div >
                                    <div >
                                        <div >
                                            <div >
                                                <span ></span>
                                            </div>
                                            <input type="text"  asp-for="BannerTitle" placeholder="Banner Title" aria-label="bannertitle" aria-describedby="basic-addon1">
                                        </div>
                                    </div>
                                </div>
                            </div>
                            <div >
                                <div >
                                    <div >
                                        <label>Banner Description</label>
                                        <div >
                                            <textarea  asp-for="BannerDescription" aria-label="Banner Description" rows="6"></textarea>
                                        </div>
                                    </div>
                                </div>
                                <div >
                                    <div >
                                        <span >Drop file here or click to upload</span>
                                        <input type="file" asp-for="BannerImg1" name="myFile"  accept="image/*" data-allowed-file-extensions='["jpg", "png" , "jpeg"]' required>
                                    </div>
                                </div>
                            </div>
                            <div >
                                <div >
                                    <div >
                                        <div >
                                            <div >
                                                <span ></span>
                                            </div>
                                            <input type="text"  asp-for="BannerIndex" placeholder="Banner Index" aria-label="bannerindex" aria-describedby="basic-addon1">
                                        </div>
                                    </div>
                                </div>
                                <div >
                                    <div >
                                        <div >
                                            <div >
                                                <span ></span>
                                            </div>
                                        </div>
                                    </div>
                                </div>
                            </div>
                            <div  align="center">
                                <button type="submit" >Edit Banner</button>
                            </div>
                        </div>
                    </div>
                </div>
            </div>
        </div>
    </div>
</form>

When i try To Edit the data in the browser it Throw exception, in database i have value but when i tried to fetch data its showing error.

thank you in advance to everybody for any help or advice.

CodePudding user response：

According to the error message it is necessary to pass the BannerViewModels instance instead of the Banner entity:

public ActionResult EditBanner(int id)
{
    var abd = _db.Banner.Where(a => a.BannerId == id)
        .Select(b => new BannerViewModels()
        {
            BannerId = b.BannerId,
            BannerTitle = b.BannerTitle,
            BannerDescription = b.BannerDescription,
            BannerImg = b.BannerImg,
            BannerUrl = b.BannerUrl,
            BannerIndex = b.BannerIndex,
            BMasterId = b.BMasterId,
            IsDeleted = b.IsDeleted
        })
        .FirstOrDefault();

    return View(abd);
}

Passing an entity to the view as a data model is bad idea.

See the following post: Why it's not a good idea to pass entities as Models in MVC?