MVC Generic Dropdownlist for Razor

Introduction

This code is used to build the generic dropdownlist to query the list from DB so that no need to reproduce the code everywhere .

Using the code

Step 1

Write a static method to perform the logic . Here I query from the database using Entity Framework and for the type T, you need to pass the model name (Database -table name), since the Razor HTML helper accepts the type SelectListItem, we must have the same return type

public class Helpers
{ 
    public static List<SelectListItem> GetDropDownList<T>(
           string text, string value, string selected) where T : class
    {
        List<SelectListItem> list = new List<SelectListItem>();
        list.Add(new SelectListItem { Text = "-Please select-", Value = string.Empty });
        IQueryable<T> result = Db.Repository<T>();
        var lisData = (from items in result
                       select items).AsEnumerable().Select(m => new SelectListItem
                       {
                           Text = (string)m.GetType().GetProperty(text).GetValue(m),
                           Value = (string)m.GetType().GetProperty(value).GetValue(m),
                           Selected = (selected != "") ? ((string)
                             m.GetType().GetProperty(value).GetValue(m) == 
                             selected ? true : false) : false,
                       }).ToList();
        list.AddRange(lisData);
        return list;
    }
}

Step 2

Then in the Controller action, you can call the static method as below and pass the result to the MVC view using the ViewBag:

var countryList = Helpers.GetDropDownList<Country>("Name", "CountryCode", "SG");
var currencyList = Helpers.GetDropDownList<CurrencyCode>("Name", "Code", "AUD");

ViewBag.CountryCode = countryList;
ViewBag.Currency = currencyList;

Step 3

You can call the ViewBag in the dropdownlist Html Helper as shown below in the MVC Razor View which is tied to the model. 

@model MvcApplication1.Model.Model1
   <tr>
       <td>@Html.LabelFor(model => model.Currency):</td>
       <td>@Html.DropDownList("Currency", ViewData["Currency"] 
         as SelectListItem[])    @Html.ValidationMessageFor(model => model.Currency)</td>
                    
   </tr>
   <tr>
       <td>@Html.LabelFor(model => model.Country):</td>
       <td>@Html.DropDownList("Country", 
         ViewData["Country"] as SelectListItem[])
         @Html.ValidationMessageFor(model => model.CountryCode)</td>
        
   </tr>