In this article, I will explain the concept of HTTP verbs in MVC 5. I will also explain the various types of HTTP verbs in MVC 5 and how it works in the project.

What is HTTP?

• HTTP stands for hypertext transfer protocol.
• This protocol works while working with a client-server application.
• This protocol provides communication between the client and the server.

HTTP provides methods (verbs) for the actions performed on a response. HTTP verbs are used on an action method. HTTP provides the following main verbs.

• Get
• Post
• Put
• Delete

HTTP Get
This verb is used to get existing data from the database. In HttpGet, data travels in the URL only. To use the HttpGet method, we use HttpGet attribute on the Action method. It is also the default HTTP verb.

Example
domain.com/student/GetStudent/1
domain.com/student/GetStudent?studentid=1

[HttpGet] 
public object GetStudent(int studentid) 
{ 
   // code here 
} 

HTTP Post

This verb is used while we have to create a new resource in the database. In HttpPost, data travels in the URL and body. To use HttpPost method, we use HttpPost attribute on the Action method.

Example
domain/student/Studentsave

Body - Json body
[HttpPost] 
public object Studentsave(studentclass obj) 
{ 
} 

HTTP Put
This verb is used while we have to update an existing resource in the database. In HttpPut, the data travels in the URL and body. To use HttpPut method, we use HttpPut attribute on the Action method.

Example
domain.com/student/studentupdate/1

Body- Json body
[HttpPut] 
public object Studentupdate(int studentid ,Studentclass objVM) 
{ 
} 

HTTP Delete
This verb is used while we have to delete the existing resources in the database. In HttpDelete, data travels in the URL and body. To use HttpDelete, we use HttpDelete attribute on the Action method.

Example
domain.com/student/studentdelete/1

[HttpDelete]   
public object Studentupdate(int studentid)   
{   
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ASP.NET MVC 6 Hosting  is the technology that brought me to Microsoft and the west-coast and it’s been fun getting to grips with it these last few weeks. Last week I needed to expose RSS feeds and checked out some examples online but was very disappointed. If you find yourself contemplating writing code to solve technical problems rather than the specific business domain you work in you owe it to your employer and fellow developers to see what exists before churning out code to solve it.

The primary excuse (and I admit to using it myself) is “X is too bloated, I only need a subset. I can write that quicker than learn their solution.” but a quick reality check:

1. Time – code always takes longer than you think

2. Bloat – indicates the problem is more complex than you realize

3. Growth – todays requirements will grow tomorrow

4. Maintenance – fixing code outside your business domain

5. Isolation – nobody coming in will know your home-grown solution

The RSS examples I found had their own ‘feed’ and ‘items’ classes and implemented flaky XML rendering by themselves or as MVC view pages.

If these people had spent a little time doing some research they would have discovered .NET’s built in SyndicatedFeed and SyndicatedItem class for content and two classes (Rss20FeedFormatter and Atom10FeedFormatter )  to handle XML generation with correct encoding, formatting and optional fields. All that is actually required is a small class to wire up these built-in classes to MVC.

using System;
using System.ServiceModel.Syndication;
using System.Text;
using System.Web;
using System.Web.Mvc;
using System.Xml;
namespace MyApplication.Something
{
    public class FeedResult : ActionResult
    {
        public Encoding ContentEncoding { get; set; }
        public string ContentType { get; set; }
        private readonly SyndicationFeedFormatter feed;
        public SyndicationFeedFormatter Feed{
            get { return feed; }
        }
        public FeedResult(SyndicationFeedFormatter feed) {
            this.feed = feed;
        }
        public override void ExecuteResult(ControllerContext context) {
            if (context == null)
                throw new ArgumentNullException("context");
            HttpResponseBase response = context.HttpContext.Response;
            response.ContentType = !string.IsNullOrEmpty(ContentType) ? ContentType : "application/rss+xml";
            if (ContentEncoding != null)
                response.ContentEncoding = ContentEncoding;
            if (feed != null)
                using (var xmlWriter = new XmlTextWriter(response.Output)) {
                    xmlWriter.Formatting = Formatting.Indented;
                    feed.WriteTo(xmlWriter);
                }
        }
    }
}

In a controller that supplies RSS feed simply project your data onto SyndicationItems and create a SyndicationFeed then return a FeedResult with the FeedFormatter of your choice.

public ActionResult NewPosts() {
    var blog = data.Blogs.SingleOrDefault();
    var postItems = data.Posts.Where(p => p.Blog = blog).OrderBy(p => p.PublishedDate).Take(25)
        .Select(p => new SyndicationItem(p.Title, p.Content, new Uri(p.Url)));
    var feed = new SyndicationFeed(blog.Title, blog.Description, new Uri(blog.Url) , postItems) {
        Copyright = blog.Copyright,
        Language = "en-US"
    };
    return new FeedResult(new Rss20FeedFormatter(feed));
}

This also has a few additional advantages:

1. Unit tests can ensure the ActionResult is a FeedResult

2. Unit tests can examine the Feed property to examine results without parsing XML

3. Switching to Atom format involved just changing the new Rss20FeedFormatter to Atom10FeedFormatter.

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In this article, I will explain about getting lookup dataa into you view ASP.Net MVC 6. This is a super common problem I encounter when building ASP.net MVC applications. I have a form that has a drop down box. Not only do I need to select the correct item from the edit model to pick from the drop down but I need to populate the drop down with the possible values.

Over the years I've used two approaches to doing this. The first is to push into the ViewBag a list of values in the controller action. That looks like
public ActionResult Edit(int id){ 
    var model = repository.get(id);

    ViewBag.Provinces = provincesService.List();

    return View(model);
}
Then in the view you can retrieve this data and use it to populate the drop down. If you're using the HTML helpers then this looks like

@Html.DropDownListFor(x=>x.province, (IEnumerable<SelectListItem>)ViewBag.Provinces)
This becomes somewhat messy when you have a lot of drop downs on a page. For instance consider something like

public ActionResult Edit(int id){ 
  var model = repository.get(id);

    ViewBag.Provinces = provincesService.List();
    ViewBag.States = statesService.List();
    ViewBag.StreetDirections = streetDirectionsService.List();
    ViewBag.Countries = countriesService.List();
    ViewBag.Counties = countiesService.List();

    return View(model);
}
The work of building up the data in the model becomes the primary focus of the view. We could extract it to a method but then we have to go hunting to find the different drop downs that are being populated. An approach I've taken in the past is to annotate the methods with an action filter to populate the ViewBag for me. This makes the action look like

[ProvincesFilter]
[StatesFilter]
[StreetDirectionsFilter]
[CountriesFilter]
[CountiesFilter]
public ActionResult Edit(int id){ 
  var model = repository.get(id);
  return View(model);
}
One of the filters might look like

public override void OnActionExecuting(ActionExecutingContext filterContext) 
{
    var countries = new List<SelectListItem>();
    if ((countries = (filterContext.HttpContext.Cache.Get(GetType().FullName) as List<SelectListItem>)) == null)
    {
        countries = countriesService.List();
        filterContext.HttpContext.Cache.Insert(GetType().FullName, countries);
    }
    filterContext.Controller.ViewBag.Countries = countries;
    base.OnActionExecuting(filterContext);
}
This filter also adds a degree of caching to the request so that we don't have to keep bugging the database.

Keeping a lot of data in the view bag presents a lot of opportunities for error. We don't have any sort of intellisense with the dynamic view object and I frequently use the wrong name in the controller and view, by mistake. Finally building the drop down box using the HTML helper requires some nasty looking casting. Any time I cast I feel uncomfortable.

@Html.DropDownListFor(x=>x.province, (IEnumerable<SelectListItem>)ViewBag.Provinces)
Now a lot of people prefer transferring the data as part of the model; this is the second approach. There is nothing special about this approach you just put some collections into the model.

I've always disliked this approach because it mixes the data needed for editing with the data for the drop downs which is really incidental. This data seems like a view level concern that really doesn't belong in the view model. This is a bit of a point of contention and I've challenged more than one person to a fight to the death over this very thing.

So neither option is particularly palatable. What we need is a third option and the new dependency injection capabilities of ASP.net MVC open up just such an option: we can inject the data services directly into the view. This means that we can consume the data right where we retrieve it without having to hammer it into some bloated DTO. We also don't have to worry about annotating our action or filling it with junk view specific code.

To start let's create a really simple service to return states.

public interface IStateService 
{
    IEnumerable<State> List();
}

public class StateService : IStateService 
{
    public IEnumerable<State> List() {
        return new List<State>
        {
            new State { Abbreviation = "AK", Name = "Alaska" },
            new State { Abbreviation = "AL", Name = "Alabama" }
        };
    }
}
Umm, looks like we're down to only two states, sorry Kentucky.

Now we can add this to our container. I took a singleton approach and just registered a single instance in the Startup.cs.

services.AddInstance(typeof(IStateService), new StateService()); 
This is easily added the the view by adding

@inject ViewInjection.Services.IStateService StateService
As the first line in the file. Then the final step is to actually make use of the service to populate a drop down box:

<div class="col-lg-12"> 
        @Html.DropDownList("States", StateService.List().Select(x => new SelectListItem { Text = x.Name, Value = x.Abbreviation }))
</div> 

That's it! Now we have a brand new way of getting the data we need to the view without having to clutter up our controller with anything that should be contained in the view.

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In this article I show you, how easy it is to make a CheckBox on ASP.NET. The use of radio buttons and checkboxes using ASP.Net programming where the function of the radio button is choosing just one selection with a circle that is a point in the middle if we choose it. While the checkbox is square shaped that there is a tick if selected. To create a function of the radio button. We will explain below:

• First you must create a project by choosing ASP.Net which is in the File> New Project> Other Languages> Visual C #> Web> Select Empty ASP.Net Web Application.
• Fill in the name and click OK aspproject05
• Right Click On aspproject05 in the top right corner select ADD> New Item> Web Form. And give CheckBox.aspx as a name.
  
• Next create a CheckBox, button, label by entering this code is in the <div>

<asp:CheckBox ID="chkNews" Text="Do you want to get more update ?" runat="server" />
<br />
<asp:Button ID="btnSubmit" Text="Submit" runat="server" OnClick="btnSubmit_Click" /> <hr/>
<asp:Label ID="lblResult" runat="server" />

Code Description:

<Asp: CheckBox ID = "chkNews" Text = "Do you want to get more update ?" runat = "server" />
This script serves as the manufacture CheckBox with ID named chkNews, which says Do you want to get more update? sent or received by the server.

<br />
This script is used to create a new line

<Asp: Button ID = "btnSubmit" Text = "Submit" runat = "server" OnClick = "btnSubmit_Click" />
This script is used to manufacture the ID button button named btnSubmit, that says Submit sent to the server to have an action Click if the button is clicked.

<Asp: Label ID = "lblResult" runat = "server" />
This script serves to create a label with name ID lblResult the printed blanks to be sent to the server.

When you're done simply double-Click button and type in the code below:

lblResult.Text = chkNews.Checked.ToString ();


Code Description:

LblResult.Text = chkNews.Checked.ToString ();
The above code serves as outputan of chkBerita when checked or not displayed by a label that berID lblResult that are boolean. This means that when we press the button without us tick checkbox section will appear on labels False lblResult whereas if we check the CheckBox and pressing the button it will show True.

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If you have worked on ASP.NET MVC, you must be familiar with how when you type in an URL, the appropriate controller is chosen, and the action fired. Today we will dig a little deeper within the MVC request life cycle. Before we start discussing its life cycle, let's briefly understand the concept of HttpHandlers and HttpModules.

Handlers are responsible for generating the actual response in MVC. They implement the IHttpHandler class and only one handler will execute per request. On the other hand, HttpModules are created in response to life cycle events. Modules can, for example, be used for populating HttpContext objects. A request can use many modules. These classes derive from IHttpModule. We are now ready to learn about the MVC Request Life Cycle. The MVC life cycle can be briefly demonstrated as below,

When a request is fired for the first time, the Application_Start method in the Global.asax file is called. This method calls the RegisterRoutes method as below,
    public class MvcApplication : System.Web.HttpApplication 
        { 
            protected void Application_Start() 
            { 
                AreaRegistration.RegisterAllAreas(); 
                FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters); 
                RouteConfig.RegisterRoutes(RouteTable.Routes); 
                BundleConfig.RegisterBundles(BundleTable.Bundles); 
            } 
        } 

RegisterRoutes method stores the routes defined in that method, in a static collection in the Routetable class.
Each route has an HttpHandler defined for it. In our case above, the MapRoute method defines the HttpHandler.
Next, the URLRoutingModule is called. It matches the request route with the routes defined in the route table. It calls the GetHttpHandler method which returns an instance of an MVCHandler.

The MVCHandler calls the ProcessRequest method. The controller execution and initialization happens inside this method. ProcessRequest calls ProcessRequestInit, which uses ControllerFactory to select an appropriate controller based on the supplied route. The ControllerFactory calls the Controller Activator which uses the dependency resolver to create an instance of the controller class.

Once the controller is created its Execute method is called.

Now comes the point where the action must be executed. The execute method in the controller calls the ExecuteCore method which calls the InvokeAction method of ActionInvoker. Action Invoker determines which action must be selected based on certain conditions, depending upon the methods available, their names and the action selectors used for them.

Once the action is selected, Authentication & Authorization filters are fired next.
Once the action passes through the authentication and authorization filter checks, the model binding takes place. The information needed for the action to execute is gathered in this step.

OnActionExecuting action filters are fired next. Once the OnActionExecuting filters are executed a response for the action is generated. The thing to note here is that the response is generated at this stage, but not executed.

Next, the OnActionExecuted filters are executed.  Once all the filters have finished executing, the response is finally executed in the ExecuteResult method which is called from the InvokeActionResult by the ActionInvoker. If the response is a view or a partial view, the ViewEngine will render it, else it will be handled appropriately. The ExecuteResult will find the appropriate view using FindView or FindPartialView method. This method will search for the view in specific locations and then render it. This is the final step in generating the response.

If you would like to further dig into the MVC request life cycle, I would highly recommend Alex Wolf’s pluralsight course by the same name.

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In the web.config file, let us define one key named Filepath and use it in our code. The PDF file must be present there.

It is good to change the key's value when it's placed in web.config.
<appSettings> 
     <add key="FilePath" value="Anil\PDF\LDEPRD9.pdf"/> 
 </appSettings> 

Add the below code to the Home Controller.
string FilePath = ConfigurationManager.AppSettings["FilePath"].ToString(); 
public ActionResult DownloadFile() 
{ 
    try 
    { 
        byte[] bytes = System.IO.File.ReadAllBytes(FilePath); 
        using (MemoryStream inputData = new MemoryStream(bytes)) 
        { 
        using (MemoryStream outputData = new MemoryStream()) 
        { 
        string PDFFilepassword = "123456"; 
        PdfReader reader = new PdfReader(inputData); 
        PdfReader.unethicalreading = true; 
PdfEncryptor.Encrypt(reader, outputData, true, PDFFilepassword, PDFFilepassword, PdfWriter.ALLOW_SCREENREADERS);
        bytes = outputData.ToArray(); 
        Response.AddHeader("content-length", bytes.Length.ToString()); 
        Response.BinaryWrite(bytes); 
        return File(bytes, "application/pdf"); 
       } 
      } 
    } 
    catch (Exception ex) 
    { 
        throw ex; 
    } 
} 

string PDFFilepassword = "123456";   
PdfReader reader = new PdfReader(inputData);   
PdfReader.unethicalreading = true;   
PdfEncryptor.Encrypt(reader, outputData, true, PDFFilepassword, PDFFilepassword, PdfWriter.ALLOW_SCREENREADERS); 

In the PDFFilepassword variable, you can set anything as password - the file name, PAN card number, or you can validate the entered value against the values stored in the database.

In Route.config, we can define the default route with the Controller And ActionName.

After entering the right password and successful authentication, the PDF file will get opened.

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In some Web Applications, we need to show real time data to the end users, which means if any changes occur (new data available) in the Server, it needs to show an end user. For instance, you are doing chat in Facebook in one tab of your Browser. You opened another tab in the same Browser and send a message to the same user (with whom, you are doing chat in the previous chat). You will see that message will appear in both the tabs and it is called real-time push.

In order to accomplish the functionality, mentioned above, the client sends interval basis AJAX requests to the Server to check, if the data is available or not. ServerSentEvents(SSE) API helps ensure the Server will push the data to the client when the data is available in the Server.

What are Server Sent Events?
SSE is an acronym and stands for Server Sent Events. It is available in HTML5 EventSource JavaScript API. It allows a Web page to get the updates from a Server when any changes occurs in the Server. It is mostly supported by the latest Browsers except Internet Explorer(IE).

Using code
We are going to implement a requirement like there is a link button and click on it and it displays current time each second on an interval basis.
In order to achieve the same, we need to add the following action in HomeController. It sets response content type as text/event-stream. Next, it loops over the date and flushes the data to the Browser.
    public void Message() 
    { 
        Response.ContentType = "text/event-stream"; 
     
        DateTime startDate = DateTime.Now; 
        while (startDate.AddMinutes(1) > DateTime.Now) 
        { 
            Response.Write(string.Format("data: {0}\n\n", DateTime.Now.ToString())); 
            Response.Flush(); 
     
            System.Threading.Thread.Sleep(1000); 
        } 
         
        Response.Close(); 
    }

Once we are done with the Server side implementation, it's time to add the code in the client side to receive the data from the Server and displays it.

First, it adds a href link, which calls initialize() method to implement SSE. Second, it declares a div, where the data will display. Thirdly, it implements Server Sent Events(SSE) through JavaScript with the steps, mentioned below.
    In the first step, it checks whether SSE is available in the Browser or not. If it is null, then it alerts to the end user to use other Browser.
    In the second step, if SSE is available, then it creates EventSource object with passing the URL as a parameter. Subsequently, it injects the events, mentioned below.

        onopen- It calls when the connection is opened to the Server
        onmessage- It calls when the Browser gets any message from the Server
        onclose- It calls when the Server closes the connection.

    <a href="javascript:initialize();" >Click Me To See Magic</a> 
    <div id="targetDiv"></div> 
     
    <script> 
         
        function initialize() { 
            alert("called"); 
     
            if (window.EventSource == undefined) { 
                // If not supported 
                document.getElementById('targetDiv').innerHTML = "Your browser doesn't support Server Sent Events."; 
                return; 
            } else { 
                var source = new EventSource('../Home/Message'); 
     
                source.onopen = function (event) { 
                    document.getElementById('targetDiv').innerHTML += 'Connection Opened.<br>'; 
                }; 
     
                source.onerror = function (event) { 
                    if (event.eventPhase == EventSource.CLOSED) { 
                        document.getElementById('targetDiv').innerHTML += 'Connection Closed.<br>'; 
                    } 
                }; 
     
                source.onmessage = function (event) { 
                    document.getElementById('targetDiv').innerHTML += event.data + '<br>'; 
                }; 
            } 
        } 
    </script>

Output

Here, we discussed about SSE(Server Sent Events). It is very important API available in HTML5. It helps to push data from the Server to the client when any changes occurs in the Server side. If you want to use a bidirectional communication channel, you can use HTML5 Web Sockets API. The disadvantage of SSE is it is Browser dependent. If the Browser doesn't support SSE, then the user can't see the data, but it is easy to use it. You can also use SignalR for realtime pushing the data to the end user.

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I have used Entity Framework to fetch the values and used Database First approach. I would also write an article on an Entity Framework but today, I would just show you how to bind the cascading dropdown list in this blog.

I have two dropdownlists. One is for state and the other for city. I would populate the city, which is based on the state selection. You can add as many dropdownlists, as you want. For simplicity, I am using only two dropdowns.

Create table scripts
tblState
    CREATE TABLE [dbo].[tblState]( 
        [stateid] [int] NOT NULL, 
        [statename] [nvarchar](50) NULL, 
    PRIMARY KEY CLUSTERED  
    ( 
        [stateid] ASC 
    )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] 
    ) ON [PRIMARY] 
     
    GO  

tblCity

    CREATE TABLE [dbo].[tblCity]( 
        [Cityid] [int] NOT NULL, 
        [CityName] [nvarchar](50) NULL, 
        [stateid] [int] NOT NULL 
    ) ON [PRIMARY] 
     
    GO 
     
    ALTER TABLE [dbo].[tblCity]  WITH CHECK ADD FOREIGN KEY([stateid]) 
    REFERENCES [dbo].[tblState] ([stateid]) 
    GO  

I have tblState and tblCity, where I have stateid as Primary key in the tblState table and stateid as the Foreign key in tblCity table. You can insert states and cities from the database as you wish.

Now, with Entity Framework; create your EDMX file. In my case, I have named it ModelDemo.edmx.

Model
I have created a Model and named it Registration. This is not directly required but since I used a strongly typed View, so I have created Model. You can also add Model because if you write the httppost method to save the values to the database, then you would need the model.
    public class Registration 
    { 
    [Required(ErrorMessage = "Enter State")] 
            public string State { get; set; } 
    [Required(ErrorMessage = "Enter City")] 
            public string City { get; set; } 
    }  

Controller
Now, this is my Controller code.
    [HttpGet] 
    public ActionResult Details() 
            { 
                bindState(); 
                return View(); 
            } 
    -------------------------------- 
    public void bindState() 
            { 
                var state = objEF.tblStates.ToList(); 
                List<SelectListItem> li = new List<SelectListItem>(); 
                li.Add(new SelectListItem { Text = "--Select State--", Value = "0" }); 
     
                foreach (var m in state) 
                { 
     
     
                    li.Add(new SelectListItem { Text = m.statename, Value = m.stateid.ToString() }); 
                    ViewBag.state = li; 
     
                } 
            } 
    ---------------------------------- 
    public JsonResult getCity(int id) 
            { 
                var ddlCity = objEF.tblCities.Where(x => x.stateid == id).ToList(); 
                List<SelectListItem> licities = new List<SelectListItem>(); 
     
                licities.Add(new SelectListItem { Text = "--Select State--", Value = "0" }); 
                if (ddlCity != null) 
                { 
                    foreach (var x in ddlCity) 
                    { 
                        licities.Add(new SelectListItem { Text = x.CityName, Value = x.Cityid.ToString() }); 
                    } 
                } 
                return Json(new SelectList(licities, "Value", "Text", JsonRequestBehavior.AllowGet)); 
            }  

Now, if you see my Controller code, I have a httpget method Details(). I am then calling a non-action method bindState() to bind the state ddl. On selection of the state ddl, the getCity() method will be called to bind the city ddl. I have used jQuery to get the Id of the selected item and have passed it to the getCity method to get the cites for the selected state.

I have also used LINQ to get my desired select value w.r.t the Id passed.

View
Right click on action method Details(), followed by clicking Add View. I always prefer a strongly typed View and I have also created a strongly typed View in this case. The name of my View is Details.cshtml.

You need jQuery min.js. Just download it from the NuGet Package, if it’s not there.

    <script src="~/Scripts/jquery-1.10.2.min.js"></script> 
    <script type="text/javascript"> 
         
        $(document).ready(function () { 
     
            $("#State").change(function () { 
                $("#City").empty(); 
                $.ajax({ 
                    type: 'POST', 
                    url: '@Url.Action("getcity")', 
                    dataType: 'json', 
                    data: { id: $("#State").val() }, 
                    success: function (city) { 
     
                        $.each(city, function (i, city) { 
                            $("#City").append('<option value="' 
                                                       + city.Value + '">' 
                                                 + city.Text + '</option>'); 
                        }); 
                    }, 
                    error: function (ex) { 
                        alert('Failed.' + ex); 
                    } 
                }); 
                return false; 
            }) 
        }); 
    </script>  

I have added the jQuery-min.js. From the code given above, we get the Id of the state ddl.

    <div class="form-group"> 
    @Html.LabelFor(model => model.State, htmlAttributes: new { @class = "control-label col-md-2" }) 
                <div class="col-md-10"> 
                    @Html.DropDownListFor(model => model.State, ViewBag.state as List<SelectListItem>, new { style = "width: 200px;" }) 
     
                    @Html.ValidationMessageFor(model => model.State, "", new { @class = "text-danger" }) 
                </div> 
            </div> 
     
            <div class="form-group"> 
     @Html.LabelFor(model => model.City, htmlAttributes: new { @class =     "control-label col-md-2" }) 
                <div class="col-md-10"> 
          @Html.DropDownListFor(model => model.City, new SelectList(string.Empty, "Value", "Text"), "--Select City--", new { style = "width:200px" }) 
     
                    @Html.ValidationMessageFor(model => model.City, "", new { @class = "text-danger" }) 
                </div>   

I have used jQuery to get the ID of the state DDL on .change function and passed it to bind the city ddl.

Now, just run your Application and you should get the output given below and if you do not get it, then check that if you are getting any values in an Id in getCity() method. If not, then check for Id mis-match.

HostForLIFE.eu ASP.NET MVC 6 Hosting
HostForLIFE.eu is European Windows Hosting Provider which focuses on Windows Platform only. We deliver on-demand hosting solutions including Shared hosting, Reseller Hosting, Cloud Hosting, Dedicated Servers, and IT as a Service for companies of all sizes. We have customers from around the globe, spread across every continent. We serve the hosting needs of the business and professional, government and nonprofit, entertainment and personal use market segments.

In this tutorial, let me show you how to call ajax method in ASP.NET MVC.
Controller code here
    [HttpGet] 
    public JsonResult GetAjaxData(string newCode) { 
        return Json(new { 
            Status = "Ajax called succesfully", Message = "Message show succesfully" 
        }, JsonRequestBehavior.AllowGet); 
    } 

View Code Here

    @ { 
        ViewBag.Title = "Index"; 
    } < script src = "~/Scripts/jquery-1.8.2.js" > < /script> 
    <script> 
    function AjaxCall() 
    { 
    $.ajax({ 
    async: false, 
    url: $('#ajaxURL').val(), 
    type: 'GET', 
    cache: false, 
    data: { 
    newCode : "Put the data here" 
    }, 
    success: function (result) { 
    if(result.Status !=''){ 
    alert(result.Status); 
    } 
    else{ 
    alert('Ajax called failed'); 
    } 
    }, 
    error: function (result, textStatus, errorThrown) { 
    alert(errorThrown); 
    } 
    }) 
    } 
    </script > < div > < button value = "Ajax Called" 
    id = "btncalled" 
    onclick = "AjaxCall()" > Ajax Called < /button> 
    </div > @Html.Hidden("ajaxURL", Url.Action("GetAjaxData", "Demo")) 

App_Start-> route config.cs code here

    public static void RegisterRoutes(RouteCollection routes) { 
        routes.IgnoreRoute("{resource}.axd/{*pathInfo}"); 
        routes.MapRoute( 
        name: "Default", 
        url: "{controller}/{action}/{id}", 
        defaults: new { 
            controller = "Demo", action = "Index", id = UrlParameter.Optional 
        }); 
    } 

I hope it works for you! Good luck!

HostForLIFE.eu ASP.NET MVC 6 Hosting
HostForLIFE.eu is European Windows Hosting Provider which focuses on Windows Platform only. We deliver on-demand hosting solutions including Shared hosting, Reseller Hosting, Cloud Hosting, Dedicated Servers, and IT as a Service for companies of all sizes. We have customers from around the globe, spread across every continent. We serve the hosting needs of the business and professional, government and nonprofit, entertainment and personal use market segments.

Restricting or limiting the file type extensions is a key business requirement. It is not necessary that a business allows all file types to be uploaded via their web application. Sometimes, only image files are accepted by the web application, sometimes only documents, and sometimes the combination of image, documents, and compressed file types are accepted by the web system.

Today, I shall be demonstrating the process of limiting/restricting the desired upload file type extensions by implementing custom data annotation/attribute component on ASP.NET MVC5 platform. This article is not specific to image files only, you can use the provided solution with any type of file format as well.

Following are some prerequisites before you proceed any further in this tutorial.

• Knowledge of ASP.NET MVC5.
• Knowledge of HTML.
• Knowledge of Bootstrap.
• Knowledge of C# Programming.

You can download the complete source code for this tutorial or you can follow the step by step discussion below. The sample code is being developed in Microsoft Visual Studio 2015 Enterprise.

Let's begin now.

Step 1
Create a new MVC web project and name it as "ImgExtLimit".

Step 2
You need to add/update the "executionTimeout", "maxRequestLength", and "maxAllowedContentLength" property values if not already added in the "Web.config" file, as shown below.
<system.web> 
  <authentication mode="None" /> 
  <compilation debug="true" targetFramework="4.5.2" /> 
  <!-- executionTimeout = 30hrs (the value is in seconds) and maxRequestLength = 1GB (the value is in Bytes) --> 
  <httpRuntime targetFramework="4.5.2" executionTimeout="108000" maxRequestLength="1073741824" /> 
</system.web>    
<system.webServer> 
  <!-- maxAllowedContentLength = 1GB (the value is in Bytes) -->     
  <security> 
    <requestFiltering> 
      <requestLimits maxAllowedContentLength="1073741824" /> 
    </requestFiltering> 
  </security>         
 
</system.webServer> 
 
executionTimeout -> Amount of time required to process your request on the web server. The value is provided in seconds.
maxRequestLength -> Maximum size which your request can capture and send to the web server. The value is provided in bytes.
maxAllowedContentLength -> Maximum allowed size of your content (e.g. file, text data etc.) that is sent to the web server. The value is provided in bytes.

Step 3
Open the "Views->Shared->_Layout.cshtml" file and replace the code with the following.
<!DOCTYPE html> 
<html> 
<head> 
    <meta charset="utf-8" /> 
    <meta name="viewport" content="width=device-width, initial-scale=1.0"> 
    <title>@ViewBag.Title</title> 
    @Styles.Render("~/Content/css") 
    @Scripts.Render("~/bundles/modernizr") 
 
    <!-- Font Awesome --> 
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/font-awesome/4.4.0/css/font-awesome.min.css" /> 
 
</head> 
<body> 
    <div class="navbar navbar-inverse navbar-fixed-top"> 
        <div class="container"> 
            <div class="navbar-header"> 
                <button type="button" class="navbar-toggle" data-toggle="collapse" data-target=".navbar-collapse"> 
                    <span class="icon-bar"></span> 
                    <span class="icon-bar"></span> 
                    <span class="icon-bar"></span> 
                </button> 
            </div> 
        </div> 
    </div> 
    <div class="container body-content"> 
        @RenderBody() 
        <hr /> 
        <footer> 
            <center> 
                <p><strong>Copyright © @DateTime.Now.Year - <a href="http://wwww.asmak9.com/">Asma's Blog</a>.</strong> All rights reserved.</p> 
            </center> 
        </footer> 
    </div> 
 
    @*Scripts*@ 
    @Scripts.Render("~/bundles/jquery") 
 
    @Scripts.Render("~/bundles/jqueryval") 
    @Scripts.Render("~/bundles/bootstrap") 
 
    @RenderSection("scripts", required: false) 
</body> 
</html>
In the above code, I have simply created a basic default layout page and linked the require libraries into it.

Step 4
Create a new "Helper_Code\Common\AllowExtensionsAttribute.cs" file and add the following code.
//----------------------------------------------------------------------- 
// <copyright file="AllowExtensionsAttribute.cs" company="None"> 
//     Copyright (c) Allow to distribute this code and utilize this code for personal or commercial purpose. 
// </copyright> 
// <author>Asma Khalid</author> 
//----------------------------------------------------------------------- 
 
namespace ImgExtLimit.Helper_Code.Common 
{ 
    using System; 
    using System.Collections.Generic; 
    using System.ComponentModel.DataAnnotations; 
    using System.Linq; 
    using System.Web; 
 
    /// <summary> 
    /// File extensions attribute class 
    /// </summary> 
    [AttributeUsage(AttributeTargets.Field | AttributeTargets.Property, AllowMultiple = false, Inherited = true)] 
    public class AllowExtensionsAttribute : ValidationAttribute 
    { 
        #region Public / Protected Properties 
 
        /// <summary> 
        /// Gets or sets extensions property. 
        /// </summary> 
        public string Extensions { get; set; } = "png,jpg,jpeg,gif"; 
 
        #endregion 
 
        #region Is valid method 
 
        /// <summary> 
        /// Is valid method. 
        /// </summary> 
        /// <param name="value">Value parameter</param> 
        /// <returns>Returns - true is specify extension matches.</returns> 
        public override bool IsValid(object value) 
        { 
            // Initialization 
            HttpPostedFileBase file = value as HttpPostedFileBase; 
            bool isValid = true; 
 
            // Settings. 
            List<string> allowedExtensions = this.Extensions.Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries).ToList(); 
 
            // Verification. 
            if (file != null) 
            { 
                // Initialization. 
                var fileName = file.FileName; 
 
                // Settings. 
                isValid = allowedExtensions.Any(y => fileName.EndsWith(y)); 
            } 
 
            // Info 
            return isValid; 
        } 
 
        #endregion 
    } 
}

In ASP.NET MVC 5, creating customized data annotations/attributes is one of the cool features. The ASP.NET MVC 5 platform already contains a default FileExtensions attribute, but, the issue with this pre-built data annotation/attribute is that it is applicable only on string type view model properties and in my case, I am uploading the files via "HttpPostedFileBase" data type view model property. This means that the pre-built data annotation/attribute does not have any means to know the data type of the file(s) that I am uploading which will have  no effect on the limitation that is considered to be applied on the uploaded file type extensions. Of course, there are many other tricks or workarounds to go through while working with the pre-built FileExtensions attribute, but, I prefer the custom data annotation/attribute mechanism, which is much simpler.

So, in the above code, I have created a new class "AllowExtensionsAttribute" (by following the naming convention of custom attribute class) and inherited the ValidationAttribute class. Then, I have created a public property "Extensions" and set the default value with image file type extensions, which means that my custom attribute will accept only image file type to be uploaded. So, in order to allow the required file type extensions, this property will be updated at the time of my custom attribute utilization accordingly. Finally, I have overridden the "IsValid(....)" method which will receive my uploaded file as "HttpPostedFileBase" data type and from this, I will extract the file type extension of the uploaded file and then validate whether it is according to either default file type extension restriction or according to my provided file type extensions.

Step 5
Now, create a new "Models\ImgViewModel.cs" file and replace the following code in it i.e.
//----------------------------------------------------------------------- 
// <copyright file="ImgViewModel.cs" company="None"> 
//     Copyright (c) Allow to distribute this code and utilize this code for personal or commercial purpose. 
// </copyright> 
// <author>Asma Khalid</author> 
//----------------------------------------------------------------------- 
 
namespace ImgExtLimit.Models 
{ 
    using System.Collections.Generic; 
    using System.ComponentModel.DataAnnotations; 
    using System.Web; 
    using Helper_Code.Common; 
 
    /// <summary> 
    /// Image view model class. 
    /// </summary> 
    public class ImgViewModel 
    { 
        #region Properties 
 
        /// <summary> 
        /// Gets or sets Image file property. 
        /// </summary> 
        [Required] 
        [Display(Name = "Supported Files .png | .jpg")] 
        [AllowExtensions(Extensions = "png,jpg", ErrorMessage = "Please select only Supported Files .png | .jpg")] 
        public HttpPostedFileBase FileAttach { get; set; } 
 
        /// <summary> 
        /// Gets or sets message property. 
        /// </summary> 
        public string Message { get; set; } 
 
        /// <summary> 
        /// Gets or sets is valid propertty. 
        /// </summary> 
        public bool isValid { get; set; } 
 
        #endregion 
    } 
}

In the above code, I have created my view model which I will attach with my view. Here, I have created HttpPostedFileBase type file attachment property which will capture uploaded image/file data from the end-user, then I have also applied my custom "AllowExtensions" attribute to the FileAttach property and provide the list of file type extensions separated by a comma (,) that I have allowed my system to accept. Then, I have created two more properties; i.e., Message of data type string and isValid of data type Boolean for processing purpose.

Step 6
Create a new "Controllers\ImgController.cs" file and add the following code to it.
//----------------------------------------------------------------------- 
// <copyright file="ImgController.cs" company="None"> 
//     Copyright (c) Allow to distribute this code and utilize this code for personal or commercial purpose. 
// </copyright> 
// <author>Asma Khalid</author> 
//----------------------------------------------------------------------- 
 
namespace ImgExtLimit.Controllers 
{ 
    using System; 
    using System.Collections.Generic; 
    using System.Linq; 
    using System.Web; 
    using System.Web.Mvc; 
    using Models; 
 
    /// <summary> 
    /// Image controller class. 
    /// </summary> 
    public class ImgController : Controller 
    { 
        #region Index view method. 
 
        #region Get: /Img/Index method. 
 
        /// <summary> 
        /// Get: /Img/Index method. 
        /// </summary>         
        /// <returns>Return index view</returns> 
        public ActionResult Index() 
        { 
            // Initialization/ 
            ImgViewModel model = new ImgViewModel() { FileAttach = null, Message = string.Empty, isValid = false }; 
 
            try 
            { 
            } 
            catch (Exception ex) 
            { 
                // Info 
                Console.Write(ex); 
            } 
 
            // Info. 
            return this.View(model); 
        } 
 
        #endregion 
 
        #region POST: /Img/Index 
 
        /// <summary> 
        /// POST: /Img/Index 
        /// </summary> 
        /// <param name="model">Model parameter</param> 
        /// <returns>Return - Response information</returns> 
        [HttpPost] 
        [AllowAnonymous] 
        [ValidateAntiForgeryToken] 
        public ActionResult Index(ImgViewModel model) 
        { 
            try 
            { 
                // Verification 
                if (ModelState.IsValid) 
                { 
                    // Settings. 
                    model.Message = "'" + model.FileAttach.FileName + "' file has been successfuly!! uploaded"; 
                    model.isValid = true; 
                } 
                else 
                { 
                    // Settings. 
                    model.Message = "'" + model.FileAttach.FileName + "' file is not supported. "; 
                    model.isValid = false; 
                } 
            } 
            catch (Exception ex) 
            { 
                // Info 
                Console.Write(ex); 
            } 
 
            // Info 
            return this.View(model); 
        } 
 
        #endregion 
 
        #endregion 
    } 
}

In the above code, I have created a GET "Index(...)" method which will initialize the view model with default values and send it to the view page. Finally, I have created a POST "Index(...)" method which will receive an input image file from the end-user, then validate the view model for allowed file type extensions and then send the response message accordingly.

Step 7
Now, create a view "Views\Img\Index.cshtml" file and add the following code to it.
@using ImgExtLimit.Models 
 
@model ImgExtLimit.Models.ImgViewModel 
 
@{ 
    ViewBag.Title = "ASP.NET MVC5: Limit Upload File Extension"; 
} 
 
 
<div class="row"> 
    <div class="panel-heading"> 
        <div class="col-md-8"> 
            <h3> 
                <i class="fa fa-file-text-o"></i> 
                <span>ASP.NET MVC5: Limit Upload File Extension</span> 
            </h3> 
        </div> 
    </div> 
</div> 
 
<br /> 
 
<div class="row"> 
    <div class="col-md-6 col-md-push-2"> 
        <section> 
            @using (Html.BeginForm("Index", "Img", FormMethod.Post, new { enctype = "multipart/form-data", @class = "form-horizontal", role = "form" })) 
            { 
                @Html.AntiForgeryToken() 
 
                <div class="well bs-component"> 
                    <br /> 
 
                    <div class="row"> 
                        <div class="col-md-12"> 
                            <div class="col-md-8 col-md-push-2"> 
                                <div class="input-group"> 
                                    <span class="input-group-btn"> 
                                        <span class="btn btn-default btn-file"> 
                                            Browse… 
                                            @Html.TextBoxFor(m => m.FileAttach, new { type = "file", placeholder = Html.DisplayNameFor(m => m.FileAttach), @class = "form-control" }) 
                                        </span> 
                                    </span> 
                                    <input type="text" class="form-control" readonly> 
                                </div> 
                                @if (Model.isValid && !string.IsNullOrEmpty(Model.Message)) 
                                { 
                                    <span class="text-success">@Model.Message</span> 
                                } 
                                else 
                                { 
                                    <span class="text-danger">@Model.Message</span>@Html.ValidationMessageFor(m => m.FileAttach, "", new { @class = "text-danger" }) 
                                } 
                            </div> 
                        </div> 
                    </div> 
 
                    <div class="form-group"> 
                        <div class="col-md-12"> 
                        </div> 
                    </div> 
 
                    <div class="form-group"> 
                        <div class="col-md-offset-5 col-md-10"> 
                            <input type="submit" class="btn btn-danger" value="Upload" /> 
                        </div> 
                    </div> 
                </div> 
            } 
        </section> 
    </div> 
</div> 
 
@section Scripts 
{ 
    @*Scripts*@ 
    @Scripts.Render("~/bundles/bootstrap-file") 
 
    @*Styles*@ 
    @Styles.Render("~/Content/Bootstrap-file/css") 
}

In the above code, I have created a simple view for uploading the image file to the server which will validate the allowed file type extensions at the server side.

Step 8
Now, execute the project