ASP Net MVC-如何使用外键插入数据？

Question

I am new to the asp net mvc, so maybe this is easy.. I have a table with categories and a table with subcategories. Subcategories have the foreign key CategoryId. My goal is to when I am on a create form for the subcategory, to choose one category to insert it.

These are my model classes:

 public class Category
 {
    [Key]
    public int CategoryId { get; set; }

    [Required]
    public string CategoryName { get; set; }
 }


 public class SubCategory
 {
    [Key]
    public int SubCategoryId { get; set; }
    [Required]
    public string SubCategoryName { get; set; }

    // Foreign key 
    [Display(Name = "Category")]
    public int CategoryId { get; set; }

    [ForeignKey("CategoryId")]
    public virtual Category Categories { get; set; }
}

I have created repository classes that are calling stored procedures for inserting data.

And in my SubCategoryController, I am calling the repository class to insert it.

 public class SubCategoryController : Controller
{
    public ActionResult AddCat()
    {
        return View();
    }

    // POST: Employee/Create
    [HttpPost]
    public ActionResult AddCat(SubCategory Cat)
    {
        try
        {
            if (ModelState.IsValid)
            {
                SubCatRep SubCatRep = new SubCatRep();
                if (SubCatRep.AddCat(Cat))
                {
                    ViewBag.Message = "SubCat added!";
                }

            }
            return View();
        }
        catch
        {
            return View();
        }

    }
}

I have created a normal create view. But when I start my app, the CategoryID field is the number field..It does not give me an option to choose a dropdopwn or something like that from the Category table.

<div class="form-horizontal">
    <h4>SubCategory</h4>
    <hr />
    @Html.ValidationSummary(true, "", new { @class = "text-danger" })
    <div class="form-group">
        @Html.LabelFor(model => model.SubCategoryName, htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.SubCategoryName, new { htmlAttributes = new { @class = "form-control" } })
            @Html.ValidationMessageFor(model => model.SubCategoryName, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.CategoryId, htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.CategoryId, new { htmlAttributes = new { @class = "form-control" } })
            @Html.ValidationMessageFor(model => model.CategoryId, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        <div class="col-md-offset-2 col-md-10">
            <input type="submit" value="Create" class="btn btn-default" />
        </div>
    </div>
</div>
}

Do I need to create a dropdown list with the categories? And how to connect that? I have found some example that says that it would manualy do that because of the model classes. this is the link to that

Answer 1

这样尝试。

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

Answer 2

Create a View model of category and sub category and then create a view from that model. Eg

public class SubCategoryVM
{
public Subcategory subcategory {get;set;}
public List<Category > category {get;set;}
}