API:Picture of the day viewer

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In this tutorial, you will learn how to build a Wikipedia:Picture of the day viewer using the MediaWiki Action API.

Download the code from Github Browse the app on Toolforge

This tutorial will teach you how to do this using:

Step 1: Set up Python and Flask development environment[edit]

Setting up Python[edit]

This tutorial uses Python 3. You can download the latest Python version from here:

See the Python beginner's guide for further instructions on installing Python on different operating systems.

Setting up Flask[edit]

Pip is a package manager that you can use to install Flask: pip install flask. If you don't have pip already, install it from the official Pip website.

Step 2: Create a simple Flask application[edit]

If you have everything successfully installed, place the following script in app.py, inside your project folder: $HOME/picture-of-the-day-viewer/app.py. When you run it, it should display "Hello world" at http://localhost:5000/:


from flask import Flask
APP = Flask(__name__)

def hello():
  return "Hello World!"

if __name__ == "__main__":

Step 3: Picture of the day viewer[edit]

Now that you have everything set up, you can start writing code for the Picture of the Day viewer. Picture of the day, or POTD, is a featured image displayed daily on the home page of Wikipedia. You'll be getting the picture from a wiki template that changes every day.

Getting today's date[edit]

The first order of business is simply knowing what day it is. Because POTD updates daily, you need today's date to access the archives and get at a stable version of the correct picture. To do this, import Python's date class.

Next, define a new function, index(). Index() will render the web page and pass along any data associated with our API calls. See #Displaying the page for more information on the index.html file we'll be using as a template. For now, index() should contain a variable holding the current date. We'll be using it soon to compose a query to access the POTD.

from datetime import date
from flask import Flask, render_template

APP = Flask(__name__)

def index():
  todays_date = date.today().isoformat()

if __name__ == "__main__":

Calling the Action API[edit]

The Action API works by sending back data in response to HTTP requests. To do so, you will import the Python Requests library.

Next add two new variables: SESSION = requests.Session() and ENDPOINT = "https://en.wikipedia.org/w/api.php". You will use the SESSION object to make requests to the ENDPOINT url.

In a new function, fetch_potd(), call API:Images to request the picture embedded within a protected POTD page (example). From this call, use the picture's filename to call API:Imageinfo, and retrieve the image's source url. In this example, the second API call is handled in the helper function, fetch_image_src().

Wikipedia's archives lists dates by ISO standard format -- for instance, 2019-01-31, for 31 January, 2019. You can get the correct format by using the date method, isoformat().

def fetch_potd(cur_date):
  date_iso = cur_date.isoformat()
  title = "Template:POTD_protected/" + date_iso

  params = {
    "action": "query",
    "format": "json",
    "formatversion": "2",
    "prop": "images",
    "titles": title

  response = SESSION.get(url = ENDPOINT, params = params)
  data = response.json()
  filename = data["query"]["pages"][0]["images"][0]["title"]
  image_page_url = "https://en.wikipedia.org/wiki/" + title
  image_data = {
    "filename": filename,
    "image_page_url": image_page_url,
    "image_src": fetch_image_src(filename),
    "date": day

  return image_data

def fetch_image_src(filename):
  params = {
    "action": "query",
    "format": "json",
    "prop": "imageinfo",
    "iiprop": "url",
    "titles": file_name

  response = SESSION.get(url = ENDPOINT, params = params)
  data = response.json()
  page = next(iter(data["query"]["pages"].values()))
  image_info = page["imageinfo"][0]
  image_url = image_info["url"]

  return image_url

Finally, alter index() to call fetch_potd(). Import render_template from flask, and make index() return render_template("index.html", data=data).

Displaying the page[edit]

A screenshot of the Picture of the Day Viewer available on the MediaWiki Code Samples repo, at Github
Picture of the Day Viewer app screenshot

Flask templates mostly contain HTML markup, but they also use Jinja to render dynamic content. Jinja markup looks like this -- {{ variable }} -- and is used to inject Python variables or expressions into our basic page structure. Add some basic HTML 5 boilerplate and a few elements to index.html. Make sure to save it to a directory within your app, named /templates.

<!DOCTYPE html>
<html lang="en">
  <meta charset="utf-8">
  <title>Picture of the Day</title>
  <link rel="stylesheet" href="/static/style.css">

    <h1>Picture of the day:</h1>
    <div class="card">
      <div class="potd">
        <h2>{{ data.filename }}</h2>
        <a href="{{ data.image_page_url }}" target="blank">
          <img src="{{ data.image_src }}">
          <figcaption>View on Wikipedia</figcaption>
      <div class = "date-container">
      <div class = "current-date">{{ data.date.strftime("%d %B %Y") }}</div>

Making it interactive[edit]

Add a <form> element to index.html, and give it the following submit button inputs: Back and Next. When either button is selected, the form will submit a POST request, and the selected value will be passed back to app.py. This will allow users to browse through the Picture of the Day archives.

Next, update app.py with a change_date() function, for setting the date presented to the user. Also extend the / route to handle POST requests from the form. To allow app.py to read the POST request message, import Flask's Request class.

The complete Python and HTML code:

Styling your app[edit]

Flask uses a directory, named static, to contain any helper files that stay the same throughout the lifecycle of the app. This is a useful place to put any stylesheets or additional scripts. Our stylesheet will be using some colors and visual motifs based on the Wikimedia Style Guide. Place a CSS file in $HOME/picture-of-the-day-viewer/static/style.css.

Next steps[edit]

  • Got questions about this tutorial? Ask here on Discourse.
  • Contribute a demo app that you have developed using the MediaWiki API to this code samples repository.
  • Learn some ways to add descriptive text from the Picture of the day page:
    • API:Search provides snippets which can be used as a link preview
    • action=cirrusdump can be used to obtain the whole parsed text from articles on Wikis that have the Cirrussearch extension installed (see example).

See also[edit]