Generating Ticket PDFs in Open Event API Server
In the ordering system of Open Event API Server, there is a requirement to send email notifications to the attendees. These attendees receive the URL of the pdf of the generated ticket. On creating the order, first the pdfs are generated and stored in the preferred storage location and then these are sent to the users through the email.
Generating PDF is a simple process, using xhtml2pdf we can generate PDFs from the html. The generated pdf is then passed to storage helpers to store it in the desired location and pdf-url is updated in the attendees record.
The templates are written in HTML which is then converted using the module xhtml2pdf.
To store the templates a new directory was created at app/templates where all HTML files are stored. Now, The template directory needs to be updated at flask initializing app so that template engine can pick the templates from there. So in app/__init__.py we updated flask initialization with
template_dir = os.path.dirname(__file__) + "/templates" app = Flask(__name__, static_folder=static_dir, template_folder=template_dir)
This allows the template engine to pick the templates files from this template directory.
Generating PDF is done by rendering the html template first. This html content is then parsed into the pdf
file = open(dest, "wb") pisa.CreatePDF(cStringIO.StringIO(pdf_data.encode('utf-8')), file) file.close()
The generated pdf is stored in the temporary location and then passed to storage helper to upload it.
uploaded_file = UploadedFile(dest, filename) upload_path = UPLOAD_PATHS['pdf']['ticket_attendee'].format(identifier=get_file_name()) new_file = upload(uploaded_file, upload_path)
This generated pdf path is returned here
Rendering HTML and storing PDF
for holder in order.ticket_holders: if holder.id != current_user.id: pdf = create_save_pdf(render_template('/pdf/ticket_attendee.html', order=order, holder=holder)) else: pdf = create_save_pdf(render_template('/pdf/ticket_purchaser.html', order=order)) holder.pdf_url = pdf save_to_db(holder)
The html is rendered using flask template engine and passed to create_save_pdf and link is updated on the attendee record.
Sending PDF on email
These pdfs are sent as a link to the email after creating the order. Thus a ticket is sent to each attendee and a summarized order details with attendees to the purchased.
send_email( to=holder.email, action=TICKET_PURCHASED_ATTENDEE, subject=MAILS[TICKET_PURCHASED_ATTENDEE]['subject'].format( event_name=order.event.name, invoice_id=order.invoice_number ), html= MAILS[TICKET_PURCHASED_ATTENDEE]['message'].format( pdf_url=holder.pdf_url, event_name=order.event.name ) )
- Readme – xhtml2pdf
- Using xhtml2pdf and create pdfs
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