SelectList from ViewModel from repository Asp.net core

Question

This is my first post so please be gently.. I'm using vs 2017,asp.net core 2.2 I have problem with method to save object in db menaging ViewModel using repository pattern. Im trying to save id from table Category in table Offers using by VM. I would like to the Category in Offers view was display as NameCategory in DropDownList, and save value Id to Offers table. This is my files:

class:

 public class Offers
    {
        public int Id { get; set; }

        public string Title{ get; set; }            
        public string Contents{ get; set; }
        public int CategoryId { get; set; }
        public Category Categorys { get; set; }
        public string PicturePath { get; set; }
    }

 public class Category
    {
        [Key]
        public int CategoryId { get; set; }
        public string NameCategory { get; set; }
        public IEnumerable<Offers> OffersList { get; set; }
    }

ViewModel:

public class OffeersVM
    {    
        public string Title { get; set; }      
        public string Content { get; set; }        
        public Category Category{get;set;} 
        public List<IFormFile> Picture { get; set; }
    }

controller:

[HttpPost]
        public IActionResult Create(OffeersVM model)
        {
            if (ModelState.IsValid)
            {
                string uniqueName = ProcesEditPicture(model);

                Offers newOffers = new Offers 
                {
                    Title= model.Title,
                    Content = model.Content,
                    CategoryId = model.Category,//I think this is not corect...
                    PicturePath = uniqueName
                };
                _offer.Add(newOffers);
                return RedirectToAction("details", new { id = newOffers.Id });
            }
            return View();
        }

view:

@model OffeersVM
 
@{
    ViewBag.Title = "Add offer.";
}

<form asp-controller="Home" asp-action="Create" method="post" enctype="multipart/form-data">
    <div class="form-group">
        <label asp-for="Title">Title</label>
        <input asp-for="Title" class="form-control" id="exampleFormControlInput1" placeholder="Title">
        <span asp-validation-for="Title" class="text-danger"></span>
    </div>

    <div class="form-group">
        <label for="exampleFormControlSelect1">Select category.</label>
        <select class="form-control" id="exampleFormControlSelect1" asp-for="Category" asp-items="@*I't know what item...?*@">
            <option value=" test">Please select category.</option>
        </select>

        <span asp-validation-for="Category"></span>
    </div>

    <div class="form-group">
        <label for="exampleFormControlTextarea1" asp-for="Content">Content offer.</label>
        <textarea class="form-control" id="exampleFormControlTextarea1" rows="6" asp-for="Content"></textarea>
        <span asp-validation-for="Content" class="text-danger"></span>
    </div>

    <div class="form-group">
       
        <div class="col-sm-10">

            <div class="custom-file">
                <input multiple asp-for="Picture" class="form-control custom-file-input " />
                <label class="custom-file-label ">Picture</label>
            </div>
       </div>
    </div>


    <div>
        <button type="submit" class="btn btn-outline-success">Add offer</button>
    </div>
    
</form>

I do't know how to use SelectList or List to provide Id Category. If enybody know some good turtorials with repository pater , or (better) can help to solve my problem I'll be wery grateful. Adam.

P.S Sorry about my English...

Hi @AaddaammJJ,any update about this case? – Yinqiu Nov 24 '20 at 01:18 — Yinqiu, Nov 24 '20 at 01:18

score 0 · Answer 1 · answered Nov 23 '20 at 05:50

After asp-item should be SelectList or List<SelectListItem> type.

Here is a feasible solution.

First, you can do some change in your OffeersVM:

OffeersVM class:

 public class OffeersVM
{
    public string Title { get; set; }
    public string Content { get; set; }
    public int CategoryId { get; set; }
    public List<Category> Category { get; set; }
    public List<IFormFile> Picture { get; set; }
}

Then in your View,change your select to this:

 <select class="form-control" id="exampleFormControlSelect1" asp-for="CategoryId" asp-items="@(new SelectList(Model.Category,"CategoryId","NameCategory"))">
        <option value=" test">Please select category.</option>
    </select>

I simulated a piece of data for testing:

 var vm = new OffeersVM
        {
            Title = "New OfersVM",
            Content = "A OfferVM",
            Category = new List<Category>
            {
               new Category
               {
                   CategoryId=1,
                   NameCategory="AA",
                   OffersList=new List<Offers>
                   {
                       new Offers{Id=1,CategoryId=1,Contents="few",Title="fdfw"},
                       new Offers{Id=2,CategoryId=1,Contents="sdgsdg",Title="gsdg"},
                   }
               },
              new Category
              {
                   CategoryId=2,
                   NameCategory="BB",
                   OffersList=new List<Offers>
                   {
                       new Offers{Id=3,CategoryId=2,Contents="hghg",Title="fdfw"},
                       new Offers{Id=4,CategoryId=2,Contents="sddfj",Title="gsdg"},
                   }
              }
            }

Result:

SelectList from ViewModel from repository Asp.net core

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