I'm pretty new to ASP.NET MVC, I been searching for a solution for this problem but I couldn't find any proper solution. I found some solutions here on stachoverflow but nothing has worked with me. Here are some links:

Possible to access MVC ViewBag object from Javascript file?

MVC 3 - Assign ViewBag Contents to Javascript string

Here is my ajax call to the server:

var xhr = new XMLHttpRequest();
        xhr.open('POST', '/Prize/UploadPassport');
        xhr.send(formdata);
        xhr.onreadystatechange = function () {
            if (xhr.readyState == 4 && xhr.status == 200) {
                var data = JSON.parse(xhr.responseText)
                if (data.nationality != "") {
                    $('#PassportData tbody').append('<tr><td data-title="@Web.Resources.MyResources.PassportNationality">' + data.nationality + '</td><td data-title="@Web.Resources.MyResources.PassportName">' + data.passportName + '</td><td><a><i id="viewApp_' + data.passportID + '" class="fa fa-search fa-lg" onclick="ViewPassport(' + data.passportID + ');"> <iframe id="img_' + data.passportID + '" class="costumeiframe"></iframe></i></a></td></tr>');
                }
                else {
                    //var errorMsg = data.errorMsg;
                    ShowDataValidationMessage("@ViewBag.FileError"); //here i'm getting an empty string
                }
            }
        }

In my server side action I set ViewBag.FileError based on some conditions here it is:

public ActionResult UploadPassport(HttpPostedFileBase FileUpload, string PassportCopyNationality)
    {

            if (Condition)
            {
                //Database access
            }

            else
            {
                if (isFileAlreadyExist)
                {
                    ViewBag.FileError = Web.Resources.MyResources.PassportAttachmentValidationForFile;
                }
                else if (file.ContentLength > 3145728 || !isFileTypeLegal)
                {
                    ViewBag.FileError = Web.Resources.MyResources.FileError;
                }

                return Json(new { nationality = "", passportName = "", passportID = "" });
            }


        }
        catch (IOException io)
        {

            return Json("File not uploaded");
        }
    }

The problem that I'm getting an empty string

I'm pretty new to ASP.NET MVC, I been searching for a solution for this problem but I couldn't find any proper solution. I found some solutions here on stachoverflow but nothing has worked with me. Here are some links:

Possible to access MVC ViewBag object from Javascript file?

MVC 3 - Assign ViewBag Contents to Javascript string

Here is my ajax call to the server:

var xhr = new XMLHttpRequest();
        xhr.open('POST', '/Prize/UploadPassport');
        xhr.send(formdata);
        xhr.onreadystatechange = function () {
            if (xhr.readyState == 4 && xhr.status == 200) {
                var data = JSON.parse(xhr.responseText)
                if (data.nationality != "") {
                    $('#PassportData tbody').append('<tr><td data-title="@Web.Resources.MyResources.PassportNationality">' + data.nationality + '</td><td data-title="@Web.Resources.MyResources.PassportName">' + data.passportName + '</td><td><a><i id="viewApp_' + data.passportID + '" class="fa fa-search fa-lg" onclick="ViewPassport(' + data.passportID + ');"> <iframe id="img_' + data.passportID + '" class="costumeiframe"></iframe></i></a></td></tr>');
                }
                else {
                    //var errorMsg = data.errorMsg;
                    ShowDataValidationMessage("@ViewBag.FileError"); //here i'm getting an empty string
                }
            }
        }

In my server side action I set ViewBag.FileError based on some conditions here it is:

public ActionResult UploadPassport(HttpPostedFileBase FileUpload, string PassportCopyNationality)
    {

            if (Condition)
            {
                //Database access
            }

            else
            {
                if (isFileAlreadyExist)
                {
                    ViewBag.FileError = Web.Resources.MyResources.PassportAttachmentValidationForFile;
                }
                else if (file.ContentLength > 3145728 || !isFileTypeLegal)
                {
                    ViewBag.FileError = Web.Resources.MyResources.FileError;
                }

                return Json(new { nationality = "", passportName = "", passportID = "" });
            }


        }
        catch (IOException io)
        {

            return Json("File not uploaded");
        }
    }

The problem that I'm getting an empty string

• javascript
• ajax
• asp-mvc
• asp-mvc-4

• 1 Your passing json back to the client, not a view so ViewBag does not even exist. Just add the value to your JsonResult. Not to mention which @ViewBag.FileError is razor code which is parsed on the server before you pass the view to the client (in the initial page) so unless you set the value in the initial GET method, it would always return null – user3559349 Commented Jul 29, 2015 at 23:55
• @StephenMuecke sorry for that I been on rush !! – Ibrahim Amer Commented Jul 31, 2015 at 13:53

1 Answer 1

Firstly, @ViewBag.FileError (inside your script) is razor code which is parsed on the server before your view is sent to the client, so unless you include ViewBag.FileError = someValue in the GET method that generates this view, then it will always equate to null.

Secondly, your UploadPassport() method is returning a JsonResult not a view, so ViewBag does not even exist. You can resolve this by adding the value to the JsonResult, for example

 return Json(new { fileError = someValue, nationality = "", passportName = "", passportID = "" });

and then access it in the script

ShowDataValidationMessage("data.fileError");