using download_filename in render_pdf changes functionality

[SirNeuman]

Previously I used:
Python:

APP.route("/to-pdf/<string:id>")
def to_pdf(id):
    ...
    html = render_template('pdf.html', id=id)
    return render_pdf(HTML(string=html))

HTML: <a href="/to-pdf/{{id}}" target="_blank">

And it worked as expected. Upon clicking the a-tag the browser would display the pdf in a new tab. However I decided that i wanted a specific filename for when users downloaded the pdf from the browser. so i changed the Python to:

APP.route("/to-pdf/<string:id>")
def to_pdf(id):
    ...
    html = render_template('pdf.html', id=id)
    pdf_filename = "PDF-" + id
    return render_pdf(HTML(string=html), download_filename=pdf_filename)

As per the flask-weasyprint documentation. Now, however, upon clicking the a-tag a new tab does not open, and it just downloads directly to the computer without a preview. It still generates the same pdf, but I would like it to keep the functionality as before with the addition of a default custom filename. So basically I'm wondering how i can set the default filename for downloading a file, without changing the url and while still allowing the pdf to be viewable in the browser (i.e. not download directly to the computer). Thanks

[SimonSapin]

That’s not how browsers work. The download_filename="foo" parameters makes Flask-WeasyPrint add the Content-Disposition: attachment; filename="foo" header to the HTTP response. It’s that attachment value that makes browsers download a file rather than show it themselves, and the file name can not be specified without it.

Without a Content-Disposition header, browsers typically infer a file name from the last component of the path of the URL. You could have you Flask routes chosen accordingly. For example:

APP.route("/to-pdf/PDF-<string:id>.pdf")
def to_pdf(id):
    ...

By the way, you could use something like {{ url_for('to_pdf', id=id) }} in your HTML template to avoid hard-coding URLs.

[SirNeuman]

Ok thanks. In this case i actually cant use the url_for() since my id is actually set via javascript, unless there's some flask stuff i'm not aware of that lets you do that. I just used that flask-set-id in my example for simplicity.

Anyway, now i know a little bit more about how browsers work.

[SimonSapin]

url_for might not be the answer for your exact case, but you should still be able to change the URL path to fit the desired file name.

[wiltonsr]

Hello, everyone

It would be a good option to add an automatic_download boolean parameter. If it were False, the line could have the inline value instead of the attachment.

This way the behavior would be exactly what @SirNeuman needs. If the user clicks to download, the file's name would have the desired name.