单个Dropdownlistfor中的类别和子类别-MVC剃刀

Question

I have a table with Category Id and Parent Category Id.

Category Id    Category Name   Parent Category Id
     1           Desktop              0
     2           PC                   1
     3           Mac                  1

How do I return it in a dropdownlist in the below format:

Answer 1

hi buddy i looked for this much and i couldn't find it but finally i coded it myself.

i will try to tell you how i solved this problem and works great just like ur screenshot. here is my secreenshot

here is my category model it is almost same with ur model

 public class Category { public int ID { get; set; } public string CategoryName { get; set; } public int? ParentID { get; set; } [ForeignKey("ParentID")] public virtual ICollection<Category> SubCategories { get; set; } } 

then i created a View category model like this

  public class ViewModelCategory { public Category Category { get; set; } public List<SelectListItem> Categories { get; set; } public List<SelectListItem> ChildCategories { get; set; } public List<SelectListItem> AllCategories { get { List<SelectListItem> sli = new List<SelectListItem>(); foreach (SelectListItem item in Categories) { sli.Add(item); } foreach (SelectListItem item in ChildCategories) { int i = item.Text.IndexOf(">"); string text = item.Text.Substring(0, i-1); foreach (SelectListItem listItem in ChildCategories) { int k = listItem.Text.LastIndexOf(">"); string text2 = listItem.Text.Substring(k+1); if (text2.Contains(text)) { item.Text = listItem.Text + " > " + item.Text.Substring(i+2); } } sli.Add(item); } return sli; } } } 

my codes can look like little complicate but is is not actually.

there are something important in my ViewModelCategory model when u look at the model u will see 3 selectlistitem properties. i wanna talk about these first.

i created one of them called as "Categories" for main categories that has no any parent id value. second of them called as "ChildCategories" contains only subcategories that has parent id value

when u look at he controller codes u will see already.

and the last one of called as "AllCategories". this one is the important one couse i merged all categories in this property to send categories to dropdownlisfor in controller's view. but it is not just for this i also did something important in this property while i merged them when u look at the loops u will see it. i used loops to place categories to their parents

then used my ViewModelCategory model in controller like this

 ViewModelCategory vmc = new ViewModelCategory { Category = category, Categories = _businessCategories.GetItems().Where(x => x.ParentID == null).Select(x => new SelectListItem { Text = x.CategoryName, Value = x.ID.ToString() }).ToList(), ChildCategories = _businessCategories.GetItems().Where(x=>x.ParentID != null).Select(x => new SelectListItem { Text = _businessCategories.GetItems().Where(a => a.ID == x.ParentID).FirstOrDefault().CategoryName + " > " + x.CategoryName, Value = x.ID.ToString() }).ToList(), }; 

and finally i welcomed my datas from view like this

 <div class="form-group"> <label class="col-sm-4 control-label">Sub Category</label> <div class="col-sm-8"> @Html.DropDownListFor(model => model.Category.ParentID, Model.AllCategories.OrderBy(x=>x.Text), "Select Category", new {@class = "form-control"}) @Html.ValidationMessageFor(model => model.Category.ParentID) </div> </div> 

hope u will like this have a nice day

Answer 2

The best thing I can think of would be to create some class that hold the Name and Value for a drop down list and use it to create a SelectList in your Action.

public class SelectListValue{
  public string Text {get;set;}
  public string Value {get;set;}
}

public ActionResult SomeActionMethod()
{
  var categories = GetCategories() //Get your list of categories
  var selectListItems = new List<SelectListValue>();

  foreach(var item in categories)
  {
    var text = GetCategoryDisplay() //You will need to figure out how to generate the text, like Components > Web Cameras. This doesn't need to be a method. It could be a property on the Category object.

    selectListItems.Add(new SelectListValue {Text = text, Value = item.CategoryId.ToString()});
  }

  ViewData["CategoryList"] = new SelectList(selectListItems, "Value", "Text");
}

You will need to have a way somewhere, probably in your model, to take generate the name string. I am guessing you are already doing that. Then in your view you would do something like

 @Html.DropDownListFor(x => x.CategoryId, ViewData["CategoryList"] as SelectList)

This should work, or at least something like it.