How to serve a PDF file created by pdfkit.from_string() with Flask send_file() - flask

Question

I have a pdfkit PDF that is working fine as a Sendgrid attachment, created by the following function:
def wish_lists_pdf(user=current_user):
pdf_heading = "Thank you!"
pdf_subheading = "Please find the Wish Lists you signed up to sponsor listed below."
pdf_context = {
'heading': pdf_heading,
'subheading': pdf_subheading,
'user': user,
}
css = os.path.join(basedir, 'static/main.css')
pdf_content = render_template(
'partials/email_lists_pdf.html', **pdf_context)
path_wkhtmltopdf = app.config['WKHTMLTOPDF_EXE']
config = pdfkit.configuration(wkhtmltopdf=path_wkhtmltopdf)
pdf_file = pdfkit.from_string(
pdf_content, False, configuration=config, css=css)
bytes_file = BytesIO(pdf_file)
return bytes_file
Actually, sendgrid needs this line instead of the bytes encoding:
encoded_file = base64.b64encode(pdf_attachment).decode()
I tried it with this encoding and the b64 encoding as different tutorials have suggested. I don't really understand the purpose of the encoding, so that may be some of the cause for my error. In any case, here is a route that I want to serve the PDF file:
#bp.route('download_lists_pdf/<int:user_id>', methods=['GET'])
def download_lists_pdf(user_id):
user = User.query.filter_by(id=user_id).first()
pdf_file = wish_lists_pdf(user=user)
return send_file(
pdf_file,
as_attachment=True,
attachment_filename="Wish List Reminder Page.pdf",
mimetype='application/pdf',
)
This downloads a completely blank, 0kb PDF file. Can someone help me understand how to use send_file() in a way that will allow me to serve this PDF from pdfkit? Again, as a Sendgrid attachment the file works fine.
Here's the sendgrid attachment config if that's helpful...
context = {
'heading': heading,
'subheading': subheading,
'user': user,
}
message = Mail(
from_email=app.config['ADMIN_EMAIL'],
to_emails=app.config['EMAIL_RECIPIENTS'],
subject=email_subject,
html_content=render_template('partials/email_lists.html', **context),
)
encoded_file = base64.b64encode(pdf_attachment).decode()
attached_file = Attachment(
FileContent(encoded_file),
FileName('Wish List Reminder Page.pdf'),
FileType('application/pdf'),
Disposition('attachment')
)
message.attachment = attached_file
sg = SendGridAPIClient(app.config['SENDGRID_API_KEY'])
response = sg.send(message)
Thank you in advance for your assistance.
Edit: tried below and it didn't work
bytes_file = BytesIO(pdf_file)
return bytes(bytes_file), 200, {
'Content-Type': 'application/pdf',
'Content-Disposition': 'inline; filename="Wish List reminder sheet.pdf"'}

Answer 1

If you have the PDF as bytes_file,
return bytes(byte_file), 200, {
'Content-Type': 'application/pdf',
'Content-Disposition': 'inline; filename="nameofyourchoice.pdf"'}
should do the trick.

Answer 2

If you are looking to return PDF file as a response then you can try this-
pdf = BytesIO(pdf_attachment)
response = pdf.getvalue()
pdf.close()
return response, 200, {
'Content-Type': 'application/pdf',
'Content-Disposition': 'inline; filename="name_of_file.pdf"'}

Answer 3

I solved this by creating a blank template.pdf file in my templates directory then did this in the from_string function
pdfkit.from_string(
pdf_content, "templates/template.pdf", configuration=config, css=css
)
i.e pass the path to your blank template.pdf as the output instead of False
You will then invoke send_file like so:
return send_file(
'templates/template.pdf',
mimetype="pdf",
download_name="Wish List Reminder Page.pdf",
as_attachment=True,
)

Answer 4

These lines were useful for me, to redirect to a new browser tab with the pdf view. Thanks!
return bytes(byte_file), 200, {
'Content-Type': 'application/pdf',
'Content-Disposition': 'inline; filename="nameofyourchoice.pdf"'
}

Answer 5

I found a solution. It uses the PDF file returned directly from pdfkit and then uses a Flask Response for serving the file.
Here is the function that returns the PDF file:
def wish_lists_pdf(user=current_user):
pdf_heading = "Thank you!"
pdf_subheading = "Please find the Wish Lists you signed up to sponsor listed below."
pdf_context = {
'heading': pdf_heading,
'subheading': pdf_subheading,
'user': user,
}
css = os.path.join(basedir, 'static/main.css')
pdf_content = render_template(
'partials/email_lists_pdf.html', **pdf_context)
path_wkhtmltopdf = app.config['WKHTMLTOPDF_EXE']
config = pdfkit.configuration(wkhtmltopdf=path_wkhtmltopdf)
pdf_file = pdfkit.from_string(
pdf_content, False, configuration=config, css=css)
return pdf_file
And here is the view:
#bp.route('download_lists_pdf/<int:user_id>', methods=['GET'])
def download_lists_pdf(user_id):
user = User.query.filter_by(id=user_id).first()
pdf_file = wish_lists_pdf(user=user)
response = Response(pdf_file)
response.headers['Content-Disposition'] = "inline; 'Wish List reminder page'"
response.mimetype = 'application/pdf'
return response
I think it would be more ideal if it would open in a new tab, or if it downloaded without opening in the browser, but this is good enough for now.