File upload with strongly typed view and model validation

Shailendra Chauhan

Source Code Print 3 min read

17 Aug 2022

Intermediate

8.16K Views

Many times, we required to upload file with strongly-typed view and also apply validation on uploading file using data annotation validators. In this article, I would like to share, how can we upload a file and validate that file, firstly at client side and after that at server side.

How to do it..

Step 1 : Designing model with data annotation validation

public class RegistrationModel
{
 [Required(ErrorMessage = "Please Enter Your Full Name")]
 [Display(Name = "Full Name")]
 public string Name { get; set; }
 
 [Required(ErrorMessage = "Please Enter Address")]
 [Display(Name = "Address")]
 [MaxLength(200)]
 public string Address { get; set; }
 
 [Required(ErrorMessage = "Please Upload File")]
 [Display(Name = "Upload File")]
 [ValidateFile]
 public HttpPostedFileBase file { get; set; }
}

//Customized data annotation validator for uploading file
public class ValidateFileAttribute : ValidationAttribute
{
 public override bool IsValid(object value)
 {
 int MaxContentLength = 1024 * 1024 * 3; //3 MB
 string[] AllowedFileExtensions = new string[] { ".jpg", ".gif", ".png", ".pdf" };
 
 var file = value as HttpPostedFileBase;
 
 if (file == null)
 return false;
 else if (!AllowedFileExtensions.Contains(file.FileName.Substring(file.FileName.LastIndexOf('.'))))
 {
 ErrorMessage = "Please upload Your Photo of type: " + string.Join(", ", AllowedFileExtensions);
 return false;
 }
 else if (file.ContentLength > MaxContentLength)
 {
 ErrorMessage = "Your Photo is too large, maximum allowed size is : " + (MaxContentLength / 1024).ToString() + "MB";
 return false;
 }
 else
 return true;
 }
}

Step 2 : Designing view based on model

<h2>File upload with model validation</h2>
<h3 style="color: green">@ViewBag.Message</h3>

@using (Html.BeginForm("FileUpload", "Home", FormMethod.Post, new { enctype = "multipart/form-data" }))
{ 
 <fieldset>
 <legend></legend>
 <ol>
 <li>
 @Html.LabelFor(m => m.Name)
 @Html.TextBoxFor(m => m.Name, new { maxlength = 50 })
 @Html.ValidationMessageFor(m => m.Name)
 </li>
 <li>
 @Html.LabelFor(m => m.Address)
 @Html.TextAreaFor(m => m.Address, new { maxlength = 200 })
 @Html.ValidationMessageFor(m => m.Address)
 </li>
 <li class="lifile">
 @Html.TextBoxFor(m => m.file, new { type = "file" })
 @Html.ValidationMessageFor(m => m.file)
 </li>
 </ol>
 <input type="submit" value="Submit" />
 </fieldset>
}

Step 3 : Applying jQuery validation for validating file

<script type="text/jscript">
//get file size
function GetFileSize(fileid) {
 try {
 var fileSize = 0;
 //for IE
 if ($.browser.msie) {
 //before making an object of ActiveXObject, 
 //please make sure ActiveX is enabled in your IE browser
 var objFSO = new ActiveXObject("Scripting.FileSystemObject"); var filePath = $("#" + fileid)[0].value;
 var objFile = objFSO.getFile(filePath);
 var fileSize = objFile.size; //size in kb
 fileSize = fileSize / 1048576; //size in mb 
 }
 //for FF, Safari, Opeara and Others
 else {
 fileSize = $("#" + fileid)[0].files[0].size //size in kb
 fileSize = fileSize / 1048576; //size in mb 
 }
 
 return fileSize;
 }
 catch (e) {
 alert("Error is :" + e);
 }
}

//get file path from client system
function getNameFromPath(strFilepath) {
 var objRE = new RegExp(/([^\/\\]+)$/);
 var strName = objRE.exec(strFilepath);
 
 if (strName == null) {
 return null;
 }
 else {
 return strName[0];
 }
}

$(function () {
 $("#file").change(function () {
 var file = getNameFromPath($(this).val());
 if (file != null) {
 var extension = file.substr((file.lastIndexOf('.') + 1));
 switch (extension) {
 case 'jpg':
 case 'png':
 case 'gif':
 case 'pdf':
 flag = true;
 break;
 default:
 flag = false;
 }
 }
 if (flag == false) {
 $(".lifile > span").text("You can upload only jpg,png,gif,pdf extension file");
 return false;
 }
 else {
 var size = GetFileSize('file');
 if (size > 3) {
 $(".lifile > span").text("You can upload file up to 3 MB");
 }
 else {
 $(".lifile > span").text("");
 }
 }
 });
});
</script>

Step 4 : Designing Controller

public ActionResult FileUpload()
{
 return View();
}

[HttpPost]
public ActionResult FileUpload(RegistrationModel mRegister)
{
 //Check server side validation using data annotation
 if (ModelState.IsValid)
 {
 //TO:DO
 var fileName = Path.GetFileName(mRegister.file.FileName);
 var path = Path.Combine(Server.MapPath("~/Content/Upload"), fileName);
 mRegister.file.SaveAs(path);
 ViewBag.Message = "File has been uploaded successfully";
 ModelState.Clear();
 }
 return View();
}