Question

我有以下代码：

using System.Data.Entity;
using System.Diagnostics;
using System.Linq;
using System.Web.Mvc;
using WebShopGoal.Models;

namespace WebShopGoal.ViewModel
{
    public class ProductEditViewModel 
    {
        public Products Product { get; set; }
        public SelectList SupplierIdList { get; set; }
        public MultiSelectList CategoryIdList { get; set; }
        public int[] SelectedCategories { get; set; }
        public int? SupplierId { get; set; }

        private WebshopDBEntities _db; 

        public ProductEditViewModel()
        {
            _db = new WebshopDBEntities();

            SupplierIdList = new SelectList(_db.Suppliers, "Id", "Name");
            CategoryIdList = new MultiSelectList(_db.Categories, "Id", "CName");
        }

        public void Load(int id)
        {
            Product = _db.Products.Find(id);

            SupplierId = Product.SupplierId;
            SelectedCategories = Product.CategoryId.Select(p => p.Id).ToArray();    
        }

，在最后一位上，它给出了错误。我在不同的ViewModel中使用了相同的代码，但是它在那个模型中工作。我认为我使用

<div class="form-group">
    @Html.LabelFor(model => model.Product.Categories, htmlAttributes: new { @class = "control-label col-md-2" })
    <div class="col-md-10">
        @Html.ListBoxFor(model => model.SelectedCategories, Model.CategoryIdList, htmlAttributes: new { @class = "form-control" })
    </div>
</div>

有人可以帮助我吗？有人在这里搜索说使用System.Linq可以解决它，但是我已经知道了

Answer 1

我认为，您要在这里做的是：

Unable to establish a connection to the database server at localhost:3750 as it does not appear to be running

Answer 2

看起来像我想要的那样：

SelectedCategories = new int[] { Product.CategoryId };

'int'不包含'Select'的定义，找不到包含'int'类型的第一个参数的扩展方法'Select'

2 个答案: