FOSSASIA

FOSSASIA‘s Open Event Server is the REST API backend for the event management platform, Open Event. Here, the event organizers can create their events, add tickets for it and manage all aspects from the schedule to the speakers. Also, once he/she makes his event public, others can view it and buy tickets if interested.

The organizer can see all the speakers in a very detailed view in the event management dashboard. He can see the statuses of all the speakers. The possible statuses are pending, accepted, and rejected. He/she can take actions such as editing the speakers.

If the organizer wants to download the list of all the speakers as a PDF file, he or she can do it very easily by simply clicking on the Export As PDF button in the top right-hand corner.

Let us see how this is done on the server.

Server side – generating the Speakers PDF file

Here we will be using the pisa package which is used to convert from HTML to PDF. It is a html2pdf converter which uses ReportLab Toolkit, the HTML5lib and pyPdf. It supports HTML5 and CSS 2.1 (and some of CSS 3). It is completely written in pure Python so it is platform independent.

from xhtml2pdf import pisa<

We have a utility method create_save_pdf which creates and saves PDFs from HTML. It takes the following arguments:

• pdf_data – This contains the HTML template which has to be converted to PDF.
• key – This contains the file name
• dir_path – This contains the directory

It returns the newly formed PDF file. The code is as follows:

def create_save_pdf(pdf_data, key, dir_path='/static/uploads/pdf/temp/'):
   filedir = current_app.config.get('BASE_DIR') + dir_path

   if not os.path.isdir(filedir):
       os.makedirs(filedir)

   filename = get_file_name() + '.pdf'
   dest = filedir + filename

   file = open(dest, "wb")
   pisa.CreatePDF(io.BytesIO(pdf_data.encode('utf-8')), file)
   file.close()

   uploaded_file = UploadedFile(dest, filename)
   upload_path = key.format(identifier=get_file_name())
   new_file = upload(uploaded_file, upload_path)
   # Removing old file created
   os.remove(dest)

   return new_file

The HTML file is formed using the render_template method of flask. This method takes the HTML template and its required variables as the arguments. In our case, we pass in ‘pdf/speakers_pdf.html’(template) and speakers. Here, speakers is the list of speakers to be included in the PDF file. In the template, we loop through each item of speakers. We print his name, email, list of its sessions, mobile, a short biography, organization, and position. All these fields form a row in the table. Hence, each speaker is a row in our PDF file.

The various columns are as follows:

<thead>
<tr>
   <th>
       {{ ("Name") }}
   </th>
   <th>
       {{ ("Email") }}
   </th>
   <th>
       {{ ("Sessions") }}
   </th>
   <th>
       {{ ("Mobile") }}
   </th>
   <th>
       {{ ("Short Biography") }}
   </th>
   <th>
       {{ ("Organisation") }}
   </th>
   <th>
       {{ ("Position") }}
   </th>
</tr>
</thead>

A snippet of the code which handles iterating over the speakers’ list and forming a row is as follows:

{% for speaker in speakers %}
   <tr class="padded" style="text-align:center; margin-top: 5px">
       <td>
           {% if speaker.name %}
               {{ speaker.name }}
           {% else %}
               {{ "-" }}
           {% endif %}
       </td>
       <td>
           {% if speaker.email %}
               {{ speaker.email }}
           {% else %}
               {{ "-" }}
           {% endif %}
       </td>
       <td>
           {% if speaker.sessions %}
               {% for session in speaker.sessions %}
                   {{ session.name }}<br>
               {% endfor %}
           {% else %}
               {{ "-" }}
           {% endif %}
       </td>
      …. So on
   </tr>
{% endfor %}

The full template can be found here.

Obtaining the Speakers PDF file:

Firstly, we have an API endpoint which starts the task on the server.

GET - /v1/events/{event_identifier}/export/speakers/pdf

Here, event_identifier is the unique ID of the event. This endpoint starts a celery task on the server to export the speakers of the event as a PDF file. It returns the URL of the task to get the status of the export task. A sample response is as follows:

{
  "task_url": "/v1/tasks/b7ca7088-876e-4c29-a0ee-b8029a64849a"
}

The user can go to the above-returned URL and check the status of his/her Celery task. If the task completed successfully he/she will get the download URL. The endpoint to check the status of the task is:

and the corresponding response from the server –

{
  "result": {
    "download_url": "/v1/events/1/exports/http://localhost/static/media/exports/1/zip/OGpMM0w2RH/event1.zip"
  },
  "state": "SUCCESS"
}

The file can be downloaded from the above-mentioned URL.

Resources

• XHTML2PDF Tutorial
• Celery Tutorial