xhtml2pdf – blog.fossasia.org

Generating Ticket PDFs in Open Event API Server

Post author:poush
Post published:September 3, 2017
Post category:FOSSASIA Open Event
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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. Sample PDF PDF Template 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 PDFs 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 ) ) References Readme - xhtml2pdf https://github.com/xhtml2pdf/xhtml2pdf/blob/master/README.rst Using xhtml2pdf and create pdfs https://micropyramid.com/blog/generating-pdf-files-in-python-using-xhtml2pdf/

Open Event Server Ticket PDF: Where and Where-not to use static frame in xhtml2pdf

Post author:magdalenesuo
Post published:July 17, 2017
Post category:Event Event Management FOSSASIA GSoC Open Event
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One among the very important features of Open Event Server project is the tickets sales feature, where a user can buy a number of different tickets for a number of people after which he is given a link to download the ticket pdf. However, an issue concerning our Open Event Server project was that if a buyer bought different tickets at a time with different individual ticket holders, all tickets contained the same name, type and QR-Code, which in no way was acceptable since tickets and holders were different. We use the xhtml2pdf facility in order to convert an html to pdf. An xhtml2pdf facility helps us in converting HTML contents into PDF without the use of browser ‘print’ facility. In order to do this, we use the help of pages and frames, pages being the page of the PDF document, while a frame being that part of area within the page where the contents get stored. What is a PDF and HTML? The basic understanding of a PDF and an HTML is that, a PDF or Portable Document Format has layout such that it is measured in terms of specific width and height. However, for an HTML or Hyper Text Markup Language, we do no not have those specific widths and heights. Rather an HTML’s width depends on a person’s device of view and height can be infinitely long as desired. In terms of xhtml2pdf relation with pages and frames layout, we can identify with this diagram: +-page---------------------+ | | | +-content_frame-+ | | | | | | | | | | | | | | | | | | +---------------------+ | | | +----------------------------+ The stated issue was due to static frame in xhtml2pdf. What is that you ask? Static frames vs Content frames xhtml2pdf uses the concept of Static Frames to define content that remains the same across different pages (like headers and footers), and uses Content Frames to position the to-be-converted HTML content. Static Frames are defined through use of the @frame property -pdf-frame-content. Regular HTML content will not flow through Static Frames. Content Frames are @frame objects without this property defined. Regular HTML content will flow through Content Frames.(xhtml2pdf documentation) So, the basic idea of the use of -pdf-frame-content was to make the contents of the pdf static i.e. without having to continuously change alignments of the page. It made the whole pdf stay static. This actually caused the whole pdf content to stay constant, event while the loop was going over different name, QR-code and ticket-name values. That means the first loop content stayed over even with changes in values. Just a simple fix of not making the frame static was the solution. Here is a few insight of…