Passing a Knack object field value to an embedded non-Knack form

I'm using an embedded file uploader to get around the Knack file size restriction on uploaded files.  I have clients that regularly upload file sizes up to 2Gb.

My issue is I need to populate a hidden field in the uploader form with a field value from the order record in the Knack application (i.e., Order Number) to be able associate the uploaded files with the order they derived from.

Alternatively, are there any integrations out there the would allow me to get past the file size limitations and still have some methodology for associating the uploaded files with the order source?

Any ideas would be appreciated.

Ralph Coe

It's common for zapier to get 5XX errors, that hasn't been a problem for me with custom JS

You're correct.. I missed that.  All my uploads would fail at somewhere around 200mb. Smaller transfers never an issue. Was never able to resolve it. Perhaps something with the Zapier integration.


The Dropbox documentation (the one you linked) days that they have a max of 350gb. That's not mb that's gb. Should work in your case.

Hi Kelson,

Thanks for the info.

I originally tried the Zapier integration with Dropbox but large file transfers would always fail.  After much research I learned that the maximum dropbox file transfer size via an API is 350MB.  The maximum transfer sizes they list on their site only applies to transfers to and from the desktop. See 

Since my original post I implemented the Zapier integration for Google Drive.  Works great, there's no file transfer size limitations and storage space cheap. Zapier also allows you to append object text field values from the same record to the front-end of the filename. I can append the order number and other routing information to the filename... example: client uploads filename restoration13.stl to the application and the file is uploaded to google drive as 45382-Milling-restoration13.stl (order number-department-filename).

Since the uploaded file is also stored in the object record you'll want to create a task to clean up the files periodically.


Hi Ralph, due to XSS protection, cross browser restrictions it's not possible to edit the content of an embedded iframe using JavaScript. This is a security measure implemented by the browser. The approach you are considering isn't possible.

What you could do is integrate the Dropbox sdk and allow your users to upload to Dropbox via your knack form. This wouldn't require any sort of embedded element, and would also be very reliable. With the this method you would be able to save the file with the required order information in a manner that is seamless with your application and the end user wouldn't even notice.

If you have any questions you can contact me: