Asp.net-mvc – ASP.NET MVC Drop Down List

asp.net-mvcdrop-down-menu

I'm a newbie with ASP.NET MVC and trying to bind a Drop Down List with a data from a database. I'm making a computer packet calculator application, basically the users can select components he/she wants into his/her computer packet from a drop down list and then send the order into a email. The components must come from a database.

I'm not familiar with the MVC model so I haven't quite understood in which folder should I put which part of the application. Right now I have

-Controllers:

–HomeController

-Models

–HomeRepository

–IHomeRepository

–Database.dbml (right now I only use a table called product and the information that I need from there is

product_description and product_price)

-Views

–Home

—- Index

—- … etc …

I have managed to get all products from products table into a bulleted list and show it at Index page. So, my HomeRepository makes a datacontext from Database.dbml. There is also a public IList ListAll() method (?) where the search sentence is written. IHomeRepository has only

public interface IHomeRepository
{
  IList<product> ListAll();
}

Somehow it works and for a while I was very happy. I tried to populate a Drop Down List in Index page like this:

    <% foreach (product m in (IENumerable)ViewData.Model
{
   Html.DropDownList("processor"m new[] {
   new SelectedListItem { Text = m.product_description, Value m.product_description }, "Select a processor")
   }
}

But it shows only as many Drop Down List as I get products from the search sentence and it show only one result in every list.

What should I do? Or how should I build this kind of application? Perhaps Web Forms should be easier to do this simple application but I need to try to use the methods of eXtreme Programming, including Test Driven Development and I understood that that isn't possible with Web Forms. Well, this XP is another story…

Many thanks.

Best Answer

Assuming your action looks like this:

public ActionResult Index()
{
    IEnumerable<Product> products = Repository.ListAll();
    return View(products);
}

And the corresponding view is strongly typed to IEnumerable<Product>:

<%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage<System.Collections.Generic.IEnumerable<YourNamespace.Product>>" %>

you don't need to use a foreach statement to generate the dropdown box:

<%= Html.DropDownList("processor", Model.Select(p => new SelectListItem { 
    Text = p.product_description, 
    Value = p.product_id 
})) %>

Related Solutions

Asp.net-mvc – Compile Views in ASP.NET MVC

From the readme word doc for RC1 (not indexed by google)

ASP.NET Compiler Post-Build Step

Currently, errors within a view file are not detected until run time. To let you detect these errors at compile time, ASP.NET MVC projects now include an MvcBuildViews property, which is disabled by default. To enable this property, open the project file and set the MvcBuildViews property to true, as shown in the following example:

<Project ToolsVersion="3.5" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <PropertyGroup>
    <MvcBuildViews>true</MvcBuildViews>
  </PropertyGroup>

Note Enabling this feature adds some overhead to the build time.

You can update projects that were created with previous releases of MVC to include build-time validation of views by performing the following steps:

Open the project file in a text editor.
Add the following element under the top-most <PropertyGroup> element: <MvcBuildViews>true</MvcBuildViews>
At the end of the project file, uncomment the <Target Name="AfterBuild"> element and modify it to match the following:

<Target Name="AfterBuild" Condition="'$(MvcBuildViews)'=='true'">
    <AspNetCompiler VirtualPath="temp" PhysicalPath="$(ProjectDir)\..\$(ProjectName)" />
</Target>

C# – How to create a dropdownlist from an enum in ASP.NET MVC

For MVC v5.1 use Html.EnumDropDownListFor

@Html.EnumDropDownListFor(
    x => x.YourEnumField,
    "Select My Type", 
    new { @class = "form-control" })

For MVC v5 use EnumHelper

@Html.DropDownList("MyType", 
   EnumHelper.GetSelectList(typeof(MyType)) , 
   "Select My Type", 
   new { @class = "form-control" })

For MVC 5 and lower

I rolled Rune's answer into an extension method:

namespace MyApp.Common
{
    public static class MyExtensions{
        public static SelectList ToSelectList<TEnum>(this TEnum enumObj)
            where TEnum : struct, IComparable, IFormattable, IConvertible
        {
            var values = from TEnum e in Enum.GetValues(typeof(TEnum))
                select new { Id = e, Name = e.ToString() };
            return new SelectList(values, "Id", "Name", enumObj);
        }
    }
}

This allows you to write:

ViewData["taskStatus"] = task.Status.ToSelectList();

by using MyApp.Common