Asp.net mvc Async File Uploading using JQuery

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Introduction:

Background:

Once upon a time i came across scenario where i needed to upload file in my asp.net mvc web application but its quite simple if we want full post-back, but i was thinking of doing it using Ajax by doing Partial Post-back.

Using JQuery to post standard forms is extremely simple, but when posting multi-part forms for uploading files it's not so intuitive.  This is due to browser security restrictions and sandboxing.  Today I'm going to show you how to fake an asynchronous upload without reloading the page and get a result back from the server.

 First Idea that came in my mind was using mvc helper Ajax.BeginForm and i came to know that it not supports file upload by partial post-back, it will do post-back.


Second Idea that was in my mind is to use JQuery and AJAX to post file on server so that i can avoid post-back, i tried my own way by posting file and returning partial view via AJAX but same issue was happening the partial view was rendering independently not on the same view, then i  searched on internet and found a way.

This method uses IFrame and do a fake async postback and it looks like that file uplaoding via ajax, as our view remains same.
 

How It Works

Main View

Here is my view code i have created a form using mvc Helper and after the form i added an iframe in which our form will be posted:
 

@{
    ViewBag.Title = "Ajax File Uploading";
    Layout = "~/Views/Shared/_Layout.cshtml";
}

<h2>Ajax File Uploading</h2>


<div>

    <div>
        <h1>Upload File</h1>
    </div>


    @using (Html.BeginForm("Upload", "Home", FormMethod.Post,
    new
    {
        enctype = "multipart/form-data",
        id = "ImgForm",
        name = "ImgForm",
        target = "UploadTarget"
    }))
    {
        
@* DataBase Record ID as Hidden Field against which we are uplaoding file  *@
         
        @Html.Hidden("ID", 65512)
        <div style="width: 100px; margin: auto; float: left; line-height: 30px; font-weight: bold;">File</div>
     
         
        <div style="width: 200px; float: left; margin: auto;">

            <input type="file" id="uploadFile" name="file" data-val="true" data-val-required="please select a file" />
            <span id="validityMessages" style="color: Red;"></span>
        </div>

         
        <div style="clear: both;"></div>
     
        <div style="width: auto; margin-top: 3%;">
            <div style="margin: 5% 18%;">
                <input id="upload" type="button" value="Upload" name="Upload" onclick="UploadImage()" />
                <span id="uploadLoader" style="display: none;">
                    <img id="searchLoader" src="@Url.Content("~/Content/Images/loader.gif")" />Uploading Please Wait</span>
            </div>
        </div>
           
     
    }
    <div id="uploadsContainer"></div>
    <iframe id="UploadTarget" name="UploadTarget" onload="UploadImage_Complete();" style="position: absolute; left: -999em; top: -999em;"></iframe>
</div>




@section Scripts{

    <script type="text/javascript">

        $(document).ready(function () {

            $('img.delUpload').live('click', function () {

                var Id = this.id;

                var url = '@Url.Action("DeleteFile","Home")';

                url = url + "?id=" + Id
                $.get(url, function (response) {

                    $('#uploadsContainer').html(response);


                });


            });

        });


    </script>



    <script type="text/javascript">
        var isFirstLoad = true;

        function UploadImage() {



            // check for size of file not greater than 1MB
            if ($("#uploadFile").val()) {


                var iSize = ($("#uploadFile")[0].files[0].size / 1024);


                iSize = (Math.round((iSize / 1024) * 100) / 100);

                if (iSize > 4) {

                    alert("File must be less than 4MB");

                    $('span#validityMessages').html("File must be less than 4MB");



                    return;

                }
                else {
                    // on form post showing Busy Indicator
                    $('#uploadLoader').show();
                    $("#ImgForm").submit(); // post form
                    console.log(iSize + "Mb");
                }
            }

                // check for no file selected for upload

            else {


                $('span#validityMessages').html("Please select a File of size less than 4MB!");


                return;
            }


        }

        function UploadImage_Complete() {
            //Check to see if this is the first load of the iFrame
            if (isFirstLoad == true) {
                isFirstLoad = false;

            }


            $('#uploadLoader').hide();


            //Reset the image form so the file won't get uploaded again
            document.getElementById("ImgForm").reset();

            // this call will get uploads if any exists on server against this id and after successfull upload refreshing partial view to get the latest uploads
            GetFiles();


        }


        function GetFiles() {

            var url = '@Url.Action("GetFiles","Home")';

            var Id = $('input#ID').val();
            url = url + "?id=" + Id
            $.get(url, function (response) {

                $('#uploadsContainer').html(response);


            });

        }

    </script>
}

 

 Uploads ViewModel

 

public class UploadsViewModel
    {
        public long ID { get; set; }
        public List<file> Uploads { get; set; }

        public UploadsViewModel()
        {
            this.Uploads = new List<file>();
        }
    }


    public class File
    {
        public string FilePath { get; set; }
        public long FileID { get; set; }
        public string FileName { get; set; }
    }

Upload Controller Method

Here is my controller method, i am taking two parameters input one is the posted form, in form i am posting some values in hidden fields required for DB updates and second parameter is posted file, i am simply saving the file in Uploads directory on server and updating a table in DB using Entity Framework and at the end returning partial view which will display the uploaded file name, thumbnail if its a image type file and button for deleting the file.

For this post i am storing the state in Session:
 

[HttpPost]
public ActionResult Upload(FormCollection form, HttpPostedFileBase file)
{

    UploadsViewModel uploadsViewModel = Session["Uploads"] != null ? Session["Uploads"] as UploadsViewModel : new UploadsViewModel();


    uploadsViewModel.ID = long.Parse(form["id"]);

    File upload = new File();
    upload.FileID = uploadsViewModel.Uploads.Count + 1;
    upload.FileName = file.FileName;
    upload.FilePath = "~/Uploads/" + file.FileName;



    //if (file.ContentLength < 4048576)    we can check file size before saving if we need to restrict file size or we can check it on client side as well
    //{

        if (file != null)
        {
            file.SaveAs(Server.MapPath(upload.FilePath));
            uploadsViewModel.Uploads.Add(upload);
            Session["Uploads"] = uploadsViewModel;
        }

        // Save FileName and Path to Database according to your business requirements

    //}


    return PartialView("~/Views/Shared/_UploadsPartial.cshtml", uploadsViewModel.Uploads);
}

 

Uploads Partial View