ASP.NET MVC Code Review #2 - A Way of Working with Html Select Element (AKA DropDownList) In ASP.NET MVC

This is the #2 of the series of blog posts which is about some core scenarios on ASP.NET MVC: A Way of Working with Html Select Element (AKA DropDownList) In ASP.NET MVC
2011-12-30 16:28
Tugberk Ugurlu


This is the #2 of the series of blog posts which is about some core scenarios on ASP.NET MVC. In this one, code review #2, I will try to show you the best way of working with Html Select element (AKA DropDownList) in ASP.NET MVC. Here is the code:

Repository Class which generates the dummy data for the demo:

public class ProductCategory {

    public int CategoryId { get; set; }
    public string CategoryName { get; set; }
}

public class ProductCategoryRepo {

    public List<ProductCategory> GetAll() {

        List<ProductCategory> categories = new List<ProductCategory>();

        for (int i = 1; i <= 10; i++) {

            categories.Add(new ProductCategory { 
                CategoryId = i,
                CategoryName = string.Format("Category {0}", i)
            });
        }

        return categories;
    }
}

Controller:

public class SampleController : Controller {

    private readonly ProductCategoryRepo productCategoryRepo = 
         new ProductCategoryRepo();

    public ActionResult Index() {

        registerProductCategorySelectListViewBag();
        return View();
    }

    private void registerProductCategorySelectListViewBag() {

        ViewBag.ProductCategorySelectList = 
            productCategoryRepo.GetAll().Select(
                c => new SelectListItem { 
                    Text = c.CategoryName,
                    Value = c.CategoryId.ToString()
                }
            );
    }
}

View:

@{
    ViewBag.Title = "HTML Select List Sample";
}

<h2>HTML Select List Sample</h2>

<p>
    <strong>Product Categories:</strong>
</p>
<p>
    @Html.DropDownList(
        "ProductCategoryId", 
        (IEnumerable<SelectListItem>)ViewBag.ProductCategorySelectList
    )
</p>

Let’s see what it generates for us:

Output HTML of Select element:

<select id="ProductCategoryId" name="ProductCategoryId">
    <option value="1">Category 1</option>
    <option value="2">Category 2</option>
    <option value="3">Category 3</option>
    <option value="4">Category 4</option>
    <option value="5">Category 5</option>
    <option value="6">Category 6</option>
    <option value="7">Category 7</option>
    <option value="8">Category 8</option>
    <option value="9">Category 9</option>
    <option value="10">Category 10</option>
</select>

Just like what I expected. On the controller, you see that I newed up SelectListItem classes and pass them to the view through the ViewDataDictionary. SelectListItem class works nicely with DropDownList and DropDownListFor Html helpers within ASP.NET MVC as you see inside the view code above.

So, don’t try to reinvent the wheel and don’t get into for and foreach loops in order just to create a select element. SelectListItem has been put inside the library just for this purpose and leverage it.



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