Question: My question is similar to [Download and open pdf file using Ajax](https://stackoverflow.com/questions/1999607/download-and-open-pdf-file-using-ajax)

But not exactly the same , the reason I want an JQuery ajax is that my file is being generated dynamically from the data which would be fetched from the same page.

So basically I have a Json Object which needs to be sent to the server which would dynamically generate a file and send it back to the browser.

I would not like to use query strings on an anchor with my Json object stringyfied , 
as I think it would be a potential threat as query strings have character restrictions ( am I right here ?).

Please let me know If my workflow is right or I can achieve the same thing thing using a different flow.

Answer: 
You should not use AJAX to download files. This doesn't work. This being said you are left with 2 options:

1. action link and query string parameters or if the download must be trigerred at some specific javascript event you could also set the `window.location.href` to the action that is supposed to generate the PDF file and pass query string parameters to it.
2. or if you are afraid that you have lots of data to pass to the controller action that will generate the PDF to download you use a `<form>` with `method="POST"` and inside you use hidden fields to store as much parameters and data as you like:

```
@using (Html.BeginForm("download", "home"))
{
    ... hidden fields containing values that need to be sent to the server
    <input type="submit" value="Download PDF" />
}

```
Instead of making one more ajax call in your page you can use anchor tag and php force download to perform pdf download 

```
HTML
    <a href="www.example.com/download_file.php?file_source=example.pdf">Download pdf here</a>

PHP
<?php
$fullPath = $_GET['fileSource'];
if($fullPath) {
    $fsize = filesize($fullPath);
    $path_parts = pathinfo($fullPath);
    $ext = strtolower($path_parts["extension"]);
    switch ($ext) {
        case "pdf":
        header("Content-Disposition: attachment; filename=\"".$path_parts["basename"]."\""); // use 'attachment' to force a download
        header("Content-type: application/pdf"); // add here more headers for diff. extensions
        break;
        default;
        header("Content-type: application/octet-stream");
        header("Content-Disposition: filename=\"".$path_parts["basename"]."\"");
    }
    if($fsize) {//checking if file size exist
      header("Content-length: $fsize");
    }
    readfile($fullPath);
    exit;
}
?>

```

I am checking for file size because if you load pdf from CDN cloudfront, you won`t get the size of document which forces the document to download in 0kb, To avoid this i am checking with this condition 

```
  if($fsize) {//checking if file size exist
      header("Content-length: $fsize");
    }

```

I too was struggling with this problem, above code worked for me I hope it helps