I have been developing a web app where the user can upload a PDF file, and then later retrieve it and view it. What I have been doing to achieve this is having the PDF uploaded to a PostgreSQL database as bytea datatype (the column is called "attachment"), and then having nodeJS offer up this data to be fetched back and turned back into a PDF to view.
However I have been struggling to convert the data back into a valid PDF. This is the method I am using so far.
var file = new Blob([res[i].attachment], { type: 'application/pdf' });
var fileURL = URL.createObjectURL(file);
document.getElementById("pdf_box").data = fileURL;
The #pdf_box identifier refers to an object element in a HTML file which is used to display the PDF (this has been shown to work when I provide the file location of a dummy PDF file to the data attribute of this element).
The res[i].attachment is also shown to provide valid buffer data in JSON format, with an example provided below:
"attachment":{"type":"Buffer","data":[91,111,98,106,101,99,116,32,70,105,108,101,93]}
When I load the created fileURL into the data attribute of #pdf_box however, I get an error indicating along the lines of an invalid PDF file. My research so far appears to indicate this may be because the data is coming in as buffer whereas it needs to be in byte form, but I haven't found much that helps show me how this may be achieved or if there is a way to convert between the forms with the data I have access to? I have also seen occasional reference to a method called pdf.create(), but I cannot find documentation on this and I assume it must belong to a third-party library for JS.
If you know of any information that can help me with understanding what my problem is and what to search to figure out a solution, it would all be greatly appreciated, thank you.