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DropDownList in ASP.Net MVC 3 Razor with Entity Framework

Posted by Shirsendu Nandi Articles | ASP.NET MVC May 19, 2011
In this application I will developed a small Blog post application where, in the home page, all the blog pages will be bound to a DropDownList.
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In this application I will create a Blog post with post comments application. This application will be Object Class Mapping using Entity Framework. That means with the mapping of classes the database and table will be created automatically.

Step 1:

Create a new ASP.Net MVC 3 application with an empty web application. While creating the project, check the radio button for "UnitTest".

Step 2:

Now under the "Model" Folder create two classes.

  1. Blog
  2. Comments

    1.gif

Step 3:

Now In the Blog Class copy the following code:

public class Blog
    {
       
        [Key]      
        public int BlogId { get; set; }
 
        [Required(ErrorMessage = "BlogName is required")]
        public string BlogName { get; set; }
 
        [Required(ErrorMessage = "Description is required")]
        [StringLength(120, ErrorMessage = "Description Name Not exceed more than 120 words")]
        public string Description { get; set; }
        public string Body { get; set; } 
        public virtual  List<Comments > Comments_List { get; set; }
    }

See here we did the Validation of each property. And also hold the list of comments. That means 1 blog contains many posts. So that is a one to many relationship.
The "Virtual" keyword means it will make the relationship.

Step 4:

Now in the Comments class write the following code:

public class Comments
    {
        [Key ]
        public int CommentId { get; set; }
          public string Comment { get; set; }
        //[ForeignKey]
          public int BlogId { get; set; }
          public virtual Blog Blog { get; set; } 
    }

See here also we have the object reference of the "Blog" class. Before that I have used the virtual keyword.

Step 5:

Now it's time to make the entity class by which the database and the table will create.

Create the "DatabaseContext" folder under the project. After that create a class named "BlogDbContext.cs" under the folder. This class is an entity class.

Step 6:

Now add a Reference for the Entity Framework by clicking "Add New Reference" under the project.

2.gif

In my project I already added the reference. Without this dll the table will not be created in the database by object class mapping.

Now in the "BlogDbContext" class paste the following code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data.Entity;
using blogmvc3.Models;
 
namespace blogmvc3.DatabaseContext
{
    public class BlogDbContext:DbContext
    {
        public DbSet<Blog> Blog { get; set; }
        public DbSet<Comments> Comments { get; set; }
    }
}

See here in the Dbset we are passing a blog class and comments class. The Dbset table will be created automatically with a relation in the database.
The Namespace "System.Data.Entity;" is very important for that.

Step 7:

Now we have to configure the "web.config" file for the connection string. The web.config file is under the Main Solution Project. Not the Project web.config file.

3.gif

Now paste the following connection string into the web.config file.

<connectionStrings
    <
add name="BlogDBContext" connectionString="data source=.;Database=Blogdb;Trusted_Connection=true;" providerName="System.Data.SqlClient" />
  </connectionStrings>
4.gif

Step 8:

Now create a Controller Class named "HomeController" under the "ControllerFolder. After that check the
"Add action for create.update,delete.." so it will automatically create the action method in the Controller class.

6.gif

7.gif

Step 9:

Now in the "HomeController" class first create the object of class "BlogDbContext":

    BlogDbContext _db = new BlogDbContext();

After that in the Index Method write the following code:

public ActionResult Index()
        {
            var GenreLst = new List<string>();
 
            var GenreQry = from d in _db.Blog
                           orderby d.BlogName
                           select d.BlogName;
            GenreLst.AddRange(GenreQry.Distinct());
            ViewBag.movieGenre = new SelectList(GenreLst);
 
            return View(_db.Comments .ToList ());
 
        }

See here I selected all the Blog Name from and after that adding into the list.

Then through "ViewBag" I am passing the GenreLst.

Step 10:

Now create a master page in the razor engine under the "shared" folder. Give the Name "_LayoutPage1.cshtml".

8.gif

After that paste the following code there:

<!DOCTYPE html>
 
<html>
<
head>
    <title>@ViewBag.Title</title>
    <link href="@Url.Content("~/Content/Site.css")" rel="stylesheet" type="text/css" />
    <script src="@Url.Content("~/Scripts/jquery-1.4.4.min.js")" type="text/javascript"></script>
   @* <script src="../../Scripts/jquery-ui-1.8.11.custom.min.js" type="text/javascript"></script>
    <link href="../../Content/jquery-ui-1.8.11.custom.css" rel="stylesheet" type="text/css" />*@
</head>
 
<body>
    <div class="page">
 
        <div id="header">
            <div id="title">
                <h1>Blog Post</h1>
            </div>
 
            <div id="logindisplay">
                @*@Html.Partial("_LogOnPartial")*@
            </div>
 
            <div id="menucontainer">
 
                <ul id="menu">
                   @* <li>@html.actionlink("home", "index", "home")</li>*@
                    @*<li>@Html.ActionLink("About", "About", "Home")</li>*@
                   <li>@Html.ActionLink("home", "index", "home")</li>
                     <li>@Html.ActionLink("Article Post", "CreateLogin", "Article")</li>
                     @*<li>@Html.ActionLink("BookCab", "CreateLogin", "Cab")</li> *@
                </ul>
 
            </div>
             <script type="text/javascript"><!--                 mce: 0--></script>
        </div> 
        <div id="main">
            @RenderBody()
            <div id="footer">
            </div>
        </div>
    </div>
</body>
</
html>

Step 11:

Now go the "Home controller". Right-click the Index Method and add view. It will look like:

9.gif

Please check "Create Strongly-typed Views".

Choose Model Class "Comments" under DropDownList.

Select "Scaffold Template" list. After that press the "Add" Button. It will automatically create a view named "Index" under the "Home" folder.

Step 12:

See the Index View Engine will create the code for the list view automatically.

Paste the following code there.

@model IEnumerable<blogmvc3.Models.Comments>
 
@{
    ViewBag.Title = "Index";
    Layout = "~/Views/Shared/_LayoutPage1.cshtml";
}
 
<h2>Index</h2>
 
<p> 
    @Html.ActionLink("Create New", "Create")
</p>
<
table>
    <tr>
        <@*th>@Html.ActionLink("Search Blog", "SearchIndex")</th>*@
        <th>
            Blog Name :
        </th>
        <th></th>
        <th>
           Description :
        </th>
        <th></th>
        <th>
           Body
        </th>
        <th></th>
        <th>
            Comment :
        </th>
        <th></th>
        <th>
        BlogNAme List: @Html.DropDownList("movieGenre", "All"); 
       </th>       
    </tr>
 
@foreach (var item in Model) {
    <tr>
        <td>
            @Html.ActionLink("Edit", "Edit", new { id=item.CommentId }) |
            @Html.ActionLink("Details", "Details", new { id=item.CommentId }) |
            @Html.ActionLink("Delete", "Delete", new { id=item.CommentId })
        </td>
       
        <td> @item.Blog.BlogName</td>
         <td> @item.Blog.Description</td>
          <td> @item.Blog.Body</td>      
        <td>
            @item.Comment
        </td>       
    </tr>
}
</table>

Now see the code BlogNAme List: @Html.DropDownList("movieGenre", "All");

Here "Html.DropDownList" is accepting the MovieGenre which I passed through view bag and 2nd parameter is to display all the list.

10.gif

Now run the Code it will look like the following figure:

11.gif
See here the dropdownlist I marked with red.

Conclusion:

So in this article we have seen how to bind and display a DropDownList in ASP.Net MVC 3 razor.
  

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