File upload with JQuery and ASP.NET Generic Handler - Is it possible?

Question

I am trying to solve a small issue. I have built an entire web ASP.NET application using mostly client side (JQuery/JavaScript) code. I use generic handlers to do some lazy loading of data, as well as for auto-completes and the likes.

One of the requirements is that one page needs to be able to upload a file, as well as display meta information about the uploadead files.

I as wondering if there is a way to upload a file entirely out of JQuery/JavaScript. I researched a whole ot of plugins but they all rely on having a php backend.

My thought was to create a post:

$(function(){
    $('#submit').live('click', function(event){

        $.post('/SomeOtherHandler.ashx',  //can be '/someotherpage.aspx'
        { 
            filename: $('#fileUpload').val(), 
            timestamp: (new Date()).toString() 
        }, function(data){
             //do something if the post is successful.
        });

    });
});

Would that work? I know that if you include the json object { filename: value, timestamp: value } it will show up in the HttpContext.Request.Params collection where I can read it without problems.

The problem is however that I don't know how this will work since the FileUpload html control only stores the file name in its value. Therefore I would be sending a string to my server with the filename, not an array of bytes.

Any thoughts on this would be greatly appreciated!

Correct me if i am wrong but whenever an <input type="file".../> is used a special type of post is created: one where a mime type is supplied with the file as well as some other things. The post happens to whatever your <form action="".../> points to. When you click an <input type="submit".../> the entire contents of the form is sent via an http POST to the server side code including the file bits. A am not asking to grab the file from within JavaScript, but simply to re-create that http POST so that my handler/page can get the data from the <input type="file".../> field. — bleepzter
– bleepzter, Commented Feb 11, 2011 at 18:34
javascript cannot post a form with an input type of file. It will not upload the file. — Jeremy B.
– Jeremy B., Commented Feb 11, 2011 at 18:40
I have a similar issue. Implementing HTML5 drag and drop was a piece of cake, thanks to the File object. However, my <input type='file' /> is for browsers who do not yet support Drag an Drop (basically IE and old browsers). Still trying to find a way — harsimranb
– harsimranb, Commented Aug 6, 2012 at 18:43

Zitun · Accepted Answer · 2011-02-11 18:52:52Z

4

I'm using the uploadify plugin (http://www.uploadify.com/) - as Jeremy said, it's not in javascript - It's not possible. It's in flash. It's very easy to install.

$('#file_upload').uploadify({
   'uploader'  : '/uploadify/uploadify.swf',
   'script'    : '/uploadify/uploadify.ashx',
   'cancelImg' : '/uploadify/cancel.png',
   'folder'    : '/uploads',
   'auto'      : true,      
   'fileExt': '*.xls;*.xlsx;*.csv',
   'buttonText': 'Select your file',
   'onError'     : function (event,ID,fileObj,errorObj) {

  alert(errorObj.type + ' Error: ' + errorObj.info);

},
'onComplete'  : function(event, ID, fileObj, response, data) 
                {
                    var obj = jQuery.parseJSON(response);
                    if (obj.error != "" & obj.errror != null)
                    {
                        lblTable.html("error : " + obj.error);
                    }
                    else


                    {
                        lblTable.html(obj.table);
                       lblEditData.show();
                       lblTable.hide();
                    }

                }
 });

And on the uploadify.ashx :

public class uploadify : IHttpHandler
{

    public void ProcessRequest(HttpContext context)
    {
        System.Web.HttpPostedFile file = context.Request.Files["Filedata"];

        //Check extension
        string extension = "";
        try
        {
            extension = file.FileName.Split('.')[file.FileName.Split('.').Length - 1];
            if (extension != "xls" & extension != "xlsx" & extension != "csv") throw new Exception("Error of the extension");
        }
        catch
        {
            context.Response.Write("{\"error\",\"Error with the extension of the file\"");
        }


        string linkFile = System.Web.HttpContext.Current.Server.MapPath("~") + "uploads" + "\\" + DateTime.Now.ToString("yyMMddHHmm") + APIReportPro.DocumentPDF.RandomString(4) + "." + extension;

        file.SaveAs(linkFile);


  ...etc...

This is the nicest solution I found for asp.net

answered Feb 11, 2011 at 18:52

Zitun

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3 Comments

bleepzter Over a year ago

quick question... Is it possible to add the following to the script's url: /uploadify/uploadify.ashx?type=create&val1=val1&val2=val2... dynamically? Otherwise you have race conditions. If val1 and val2 are needed along with the file-stream to be saved to sql... then you wouldn't know if the file uploaded first or if the val1 and val2 got there on time....

Zitun Over a year ago

I'm not sure to understand what you mean... I did not try but guess that you can add param in your get query to /upladify.ashx

Alexandre Over a year ago

@Zitun you can use System.IO.Path.GetExtension to get file extension

Jeremy B. · Accepted Answer · 2011-02-11 18:38:37Z

3

You have what boils down to three options when you are uploading files to a server. You can use native html file-upload features, Flash or Java. Javascript cannot upload a file to a server, it can only decorate the built in html functionality. With that said I can only assume you are attempting to mimic ajax like uploading functionality. If that is so there is a way to upload files using an iframe which will look like you are using ajax.

You will be creating a form

<form id="file_upload_form" method="post" enctype="multipart/form-data" action="upload.aspx">
    <input name="file" id="file" size="27" type="file" /><br />
    <input type="submit" name="action" value="Upload" /><br />
    <iframe id="upload_target" name="upload_target" src="" style="width:0;height:0;border:0px solid #fff;"></iframe>
</form>

This form uses the iframe to post the file, which will cause the main page to never refresh. You can hook up your jquery to process the response the iframe returns and handle user information.

If this is not the part of the equation you were looking for please feel free to comment and clarify what it is you are looking to accomplish.

answered Feb 11, 2011 at 18:38

Jeremy B.

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1 Comment

bleepzter Over a year ago

So how do you use the iframe? Simply point the form's action to "upload.aspx"?

Community · Accepted Answer · 2017-05-23 10:26:43Z

2

If you can dictate which browsers your app is accessed through (e.g. it's an internal business app), it's worth checking out the new File API which is part of the "HTML5" stack of technologies that are beginning to show up in the latest browsers. This gives you direct access to files via clientside Javascript without the need to post the file to the server first.

If your app is public-facing then you can still use the File API, but you will need to check for support for it in your code and apply some kind of fallback mechanism (such as Uploadify) for those with older browsers.

You can read more about the File API here and here amongst other places.

edited May 23, 2017 at 10:26

CommunityBot

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answered Feb 11, 2011 at 18:34

Luke Bennett

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4 Comments

Chris B. Behrens Over a year ago

Man, it would be nice if this ever becomes widely supported...we have been waiting a LONG time for a decent way to handle uploads.

Luke Bennett Over a year ago

I think this is one that's here to stay, assuming it doesn't hit some major security issues - it's already in use by some big sites (e.g. Box.net). About time!

Todd Smith Over a year ago

I support this for Chrome, Safair and Firefox on my sites. It works great. Too bad IE9 dropped the soap on this. Opera doesn't support the File API but they do support the multiple attribute on file input.

Chris B. Behrens Over a year ago

I was going to post "and just guess which major browser doesn't support it as opposed to every other browser on the market!"

Chris B. Behrens · Accepted Answer · 2011-02-11 18:28:14Z

1

I'm pretty sure it's not possible; if it is then it's a big security hole - Javascript should not be able to get bytes from the user's hard drive.

So you're stuck using the native input type=file or using pre-existing desktop bytes, like Flash. Several popular uploaders use this method...my favorite is Uploadify. Take a look at that, and see if that doesn't suit your needs.

HTH.

answered Feb 11, 2011 at 18:28

Chris B. Behrens

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3 Comments

bleepzter Over a year ago

Uploadify relies on php backend.

Chris B. Behrens Over a year ago

Not at all - I have used this on ASP.Net many times: uploadify.com/forums/discussion/45/….

Luke Bennett Over a year ago

Yep, you're incorrect I'm afraid bleepzter - Uploadify does not require PHP.

Syed Bashar · Accepted Answer · 2011-08-16 17:32:50Z

0

I have implemented an ASP.NET Handler for uploading file using Valums ajax Upload control. You can check solution here. You can also upload large file. This handler supports IE, FF and Chrome browser. You can also drag drop multiple files from FF and Chrome (HTML 5)

http://ciintelligence.blogspot.com/2011/05/aspnet-server-side-handler-for-valums.html

answered Aug 16, 2011 at 17:32

Syed Bashar

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Comments

Vando · Accepted Answer · 2011-11-23 11:47:26Z

0

Using jquery you can do something like:

<input type="file" name="file" id="file1" runat="server" />

$("#<%=file1.ClientID%>").change(function () {
  //Do stuff
   $(this).upload('youHandler.ashx', function (res) {
     //do stuff on success
   }
}

Now on yourHandler.ashx you can do something like that:

public void ProcessRequest(HttpContext context)
{
   if (context.Request.Files.Count > 0)
   {
      var fileCount = context.Request.Files.Count;
      var fileStram = var file = context.Request.Files[0].InputStream;

      //Do whatever you want
   }
}

answered Nov 23, 2011 at 11:47

Vando

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