PDF file sent from flask to client is empty when downloaded

Question

I have a flask server that sends a pdf file with the send_file function. When I test this route on postman I can view and download the pdf. However when I try to download it through my React frontend the file is blank BUT with the correct amount of pages. I suppose the problem stems from my use of blob but I don't see how.

Server route

@app.route("/test", methods=["GET"])
def results():
    if request.method == "GET":
        return send_file("pdf-path", cache_timeout=0, as_attachment=True)

This route works fine when tested on postman. I can view the pdf

client side

axios.get(URL + '/test')
    .then(function (response) {
        if (response.status === 200) {
            const type = 'application/pdf';
            const file = new Blob([response.data], { type: type });
            saveAs(file, "test.pdf");
        }
    }
    )

Here I am using axios and file-saver. The file is downloaded but all the pages are empty.

Answer 1

Try this one,

from flask import send_file, send_from_directory
@app.route('/uploads/<path:filename>', methods=['GET', 'POST'])
def download(filename):
    uploads = os.path.join(current_app.root_path, 'uploads') # uploads is a folder
    return send_from_directory(directory=uploads, filename=filename)

send_from_directory - Most recommended method.

If you want to use send_file method,

@app.route("/get-csv/<path:filename>")
def get_csv(filename):

    safe_path = safe_join(app.config["CLIENT_CSV"], filename)

    try:
        return send_file(safe_path, as_attachment=True)
    except FileNotFoundError:
        abort(404)