but now that I think about it,
I really think you should change how your thinking to do this.
Instead of pulling in the whole file. I think you should just parse the file, create separate fields for all the invoce data and then just have a URL for the user to download the original file
So your meta data might look like this ( Just assuming since you said it was an invoice type data
{
"account:"1234567",
"fName:"Ed"
"lname:"Perry"
"Balance": 12.50
"30day": 1.00
"90day": 10.00
"Interest": 1.50
"lineitems": [ "book 123432","shoes 1234444"]
"invoce": "http://<blah>/invoice.txt"
}