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ASP.NET MVC 5 Hosting - HostForLIFE.eu :: Limit Upload File Type Extensions Via Custom Data Annotation/Attribute

clock December 21, 2018 08:15 by author Peter

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



ASP.NET MVC 6 Hosting - HostForLIFE.eu :: How to Fix Bundles Are Not Working After Hosting To MVC Application?

clock December 18, 2018 10:38 by author Peter

If your bundles are not getting configured properly in your server, I have fixed this issue, and here I am going to share with you how you can also fix this error. I hope you will like this.

Background

Recently, I hosted one of my MVC applications to Microsoft Azure cloud. And we usually publish our application in release mode, right? So here comes the problem. You can replicate the same issue in your local machine itself. Just make the debug attribute to false in your Web.config as follows.

  1. <compilation debug="false" targetFramework="4.5" />  

And when you run, you will get a prompt as follows.

Run without debugging

Just select Run without debugging option. Now once after your application is run, you can see some script errors in your browser console saying that the references are not loaded correctly.

Release more error in console

And finally I found the solution. Here we will see that.

"Bundles Are Not Working After Hosting To MVC Application"

As I said, the problem is with your bundle config settings. There are few things you must check before going to the last fix.

  • Please make sure that you have used StyleBundle for creating the style bundle.
  • Please make sure that you have used ScriptBundle for creating the style bundle.
  • Make sure that you are loading the styles using @Styles.Render.
  • Make sure that you are loading the scripts using @Scripts.Render.
  • Make sure that the folder structure is same as you have in local system.
    If none of the above solution works, you can try the last one.
  • Make sure that virtual path of bundles doesn’t contains the folder names you have in your solution.

I will explain it. In my case my bundles were as follows.

@Styles.Render("~/Scripts/JQWidgets/CSS")  
@Scripts.Render("~/Scripts/JQWidgets")  

And I have the folders JQWidgets in my root script folder. This was making the issue.


Folder structure

Now what I did is, I just changed my bundle config settings in BundleConfig.cs as follows(Renaming the folder),

bundles.Add(new ScriptBundle("~/Scripts/Grid")  
bundles.Add(new StyleBundle("~/Scripts/Grid/Styles")  

And I referenced the same bundles as follows in my views.

@Styles.Render("~/Scripts/Grid/Styles")  
@Scripts.Render("~/Scripts/Grid")  

Please try these steps and build your application. Once that is done you can publish your application to cloud. I hope this will solve your issue. Have a happy coding.

Conclusion

Did I miss anything that you may think is needed? Did you find this post useful? I hope you liked this article. Please share with me your valuable suggestions and feedback.

Your turn. What do you think?

A blog isn’t a blog without comments, but do try to stay on topic. If you have a question unrelated to this post, you’re better off posting it on C# Corner, Code Project, Stack Overflow, ASP.NET Forum instead of commenting here. Tweet or email me a link to your question there and I’ll definitely try to help if I can.

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.



About HostForLIFE.eu

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 offered the latest Windows 2016 Hosting, ASP.NET Core 2.2.1 Hosting, ASP.NET MVC 6 Hosting and SQL 2017 Hosting.


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