Question

我在ASP.NET MVC工作我想在选择列表项上绑定一个值列表（我只发布相关代码）

型号：

public class Product
{
    public int ProductId { get; set; }
    public int SubcategoryId { get; set; }
    public virtual Subcategory Subcategory { get; set; }
}

查看型号：

 public class ProductViewModel
{
    public int SelectedSubcategory { get; set; }
    public IEnumerable <SelectListItem> Subcategory { get; set; }
}

获取控制器：

 public ActionResult Create()
    {
        var subcategoryList = new ProductViewModel
        {
            Subcategory = new SelectList(db.ProductsList, "SubcategoryId", "Name")
        };

        return View(subcategoryList);
    }

查看：

 <div class="form-group">
        @Html.LabelFor(model => model.SubcategoryId, "SubcategoryId", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.DropDownListFor(m => m.SelectedSubcategory, Model.Subcategory, "-Select an option-", new { @class = "form-control" })
            @Html.ValidationMessageFor(m => m.SelectedSubcategory)
        </div>
    </div>

它没有约束价值的问题，我只得到强力打字“ - 选择一个选项 - ”，任何人都知道这里有什么问题？

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现在我得到参数但是当我尝试创建产品时出错：

错误讯息：

INSERT语句与FOREIGN KEY约束“FK_dbo.Products_dbo.Subcategories_SubcategoryId”冲突。冲突发生在数据库“proyectname”，表“dbo.Subcategories”，列“SubcategoryId”中。声明已经终止。

创建post方法：

 public async Task<string> CreateProduct(ProductViewModel model)
    {
        var product = new Product
        {
            Name = model.Name,
            Presentation = model.Presentation,
            Image = model.Image,
            Alt = model.Alt,
            SubcategoryId = model.SelectedSubcategory,
            IsDeleted = false
        };
        db.ProductsList.Add(product);
        await db.SaveChangesAsync();

Answer 1

试试这个：

控制器：

public ActionResult Create()
{
    Viewbag.SubcategoryId= new SelectList(db.ProductsList, "SubcategoryId", "Name")

    return View();
}

查看：

<div class="form-group">
    @Html.LabelFor(model => model.SubcategoryId, "SubcategoryId", htmlAttributes: new { @class = "control-label col-md-2" })
    <div class="col-md-10">
        @Html.DropDownList("SubcategoryId", null, "-Select an option-", new { @class = "form-control" })
        @Html.ValidationMessageFor(m => m.SubcategoryId)
    </div>
</div>

无法从SelectListItem获取值

1 个答案:

控制器：

查看：