CODEWITHSUNDEEP
asp.net-mvcrazorhtml.dropdownlistfor
Christopher Johnson
Christopher Johnson

Reputation: 2629

use Html.DropDownListFor() w/o using Model

I'm passing a Model into my view (.net mvc 3) that can't contain the information that I want to use to populate my drop down list.

I've never used Html.DropDownListFor() but have always just used Html.DropDownList(). I want to add another tool to my bag of tricks though and so want to try and incorporate Html.DropDownListFor().

Is it possible to use this helper with Key/Value pair set in a ViewBag variable?

Please advise, any code samples would be greatly appreciated (both front end (razor) and back end (on controller)).

TIA

Upvotes: 0

Views: 874

Answers (1)

Darin Dimitrov
Darin Dimitrov

Reputation: 1038810

Is it possible to use this helper with Key/Value pair set in a ViewBag variable?

Absolutely not. If you want to use strongly typed helpers such as Html.DropDownListFor you need a view model. And since I always recommend using a view model, here's an example:

public class MyViewModel
{
    public string SelectedId { get; set; }
    public IEnumerable<SelectListItem> Items { get; set; }
}

As you can see in this sample view model, for each dropdown you need 2 properties: a scalar property that will hold the selected value and a collection of SelectListItem that will hold the options where each option consists of a value and text.

Then it's the controller's responsibility to initialize this view model and pass it to the view:

public ActionResult Index()
{
    var model = new MyViewModel();
    // normally those values will be dynamic. They will be mapped 
    // to the view model
    model.Items = new[]
    {
        new SelectListItem { Value = "1", Text = "item 1" },
        new SelectListItem { Value = "2", Text = "item 2" },
        new SelectListItem { Value = "3", Text = "item 3" },
    };
    return View(model);
}

and then you will have a corresponding strongly typed view to this view model in which you will be able to use the strongly typed version of the helpers:

@model MyViewModel
@Html.DropDownListFor(x => x.SelectedId, Model.Items)

The following sentence from your question deserves some attention:

I'm passing a Model into my view (.net mvc 3) that can't contain the information that I want to use to populate my drop down list.

You should not be passing a model to a view. You should be passing a view model. A view model is a class that you specifically define for each view. It will contain the necessary information that this view will require. So a single view model could be composed from multiple models simply because such are the requirements of your view.

Upvotes: 1

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