Let’s Build a Stock Price CLI With Python

#python #beginners #programming #tutorial

Are you someone who can't help checking the latest stock prices every 5 minutes? Thanks to Python, getting the latest stock prices can be as easy as running python3 main.py AMZN in your terminal. In this tutorial, you will learn how to make a CLI with Python that:

Reads the ticker whose price you would like to get.
Scrapes the specified ticker's latest price.
Displays the scraped price.

Let's get started

First things first, create a new python file. For this tutorial, I'll name mine main.py. Once you have your new python file, import sys, BeautifulSoup and requests:
main.py

import sys
import requests
from bs4 import BeautifulSoup

Our CLI will need the user to input a ticker as a command-line argument after python3 main.py. Using the sys library, we can check if the user has entered a ticker and make the CLI return an error if no ticker was provided or if too many tickers were provided. This CLI will then define the ticker variable as the second argument provided by the user:
main.py

if len(sys.argv) > 2:
    print('You have specified too many tickers')
    sys.exit()

if len(sys.argv) < 2:
    print('No ticker provided')
    sys.exit()

ticker = sys.argv[1] # 0 = first argument and 1 = second argument

Now our CLI will need to scrape the provided ticker for it's latest price. We can do this using the BeautifulSoup and requests libraries.

The CLI will scrape the stock prices from yahoo finance. It will need to change the URL it scrapes based on the ticker entered by the user. Since the entered ticker gets stored inside the ticker variable, following yahoo finance's url structure, the CLI can change the url variable based on the ticker like so:
main.py

url = 'https://finance.yahoo.com/quote/' + ticker + '?p=' + ticker + '&.tsrc=fin-srch'
response = requests.get(url)

For example, if the provided ticker is AMZN, the CLI will scrape this url.
If the provided ticker is instead AAPL, the CLI will scrape this url.

Full code:

import os
import sys
import requests
from bs4 import BeautifulSoup

if len(sys.argv) > 2:
    print('You have specified too many tickers')
    sys.exit()

if len(sys.argv) < 2:
    print('No ticker provided')
    sys.exit()

ticker = sys.argv[1]

url = 'https://finance.yahoo.com/quote/' + ticker + '?p=' + ticker + '&.tsrc=fin-srch'
response = requests.get(url)

Scraping the stock price

For the actual scraping part, first go to a sample ticker's stock price webpage on yahoo finance. I'll choose AMZN for this tutorial. Locate the sample ticker's stock price element and right click on it. This will make a pop-up appear next to your cursor, click on the inspect option:

This will make a large pop-up containing this webpage's DOM appear at the right of your screen with the selected stock price element highlighted in light blue:

Select and copy the highlighted element's class property:

Now that you have this element's class property, to scrape this ticker's latest stock price, add the following code to main.py:
main.py

    soup = BeautifulSoup(response.text, 'html.parser')
    price = soup.find('body').find(class_='Trsdu(0.3s) Fw(b) Fz(36px) Mb(-4px) D(ib)')
    print('Latest stock price: ' + price.text.strip())

This code will find the stock price element through it's class property and display it's text contents using price.text.strip().

Full code:

import os
import sys
import requests
from bs4 import BeautifulSoup

if len(sys.argv) > 2:
    print('You have specified too many tickers')
    sys.exit()

if len(sys.argv) < 2:
    print('No ticker provided')
    sys.exit()

ticker = sys.argv[1]

url = 'https://finance.yahoo.com/quote/' + ticker + '?p=' + ticker + '&.tsrc=fin-srch'
response = requests.get(url)

soup = BeautifulSoup(response.text, 'html.parser')
price = soup.find('body').find(class_='Trsdu(0.3s) Fw(b) Fz(36px) Mb(-4px) D(ib)')
print('Latest stock price: ' + price.text.strip())

One last thing!
Put the last piece of code into a try: statement and return an error if the user entered an invalid ticker:

import os
import sys
import requests
from bs4 import BeautifulSoup

if len(sys.argv) > 2:
    print('You have specified too many tickers')
    sys.exit()

if len(sys.argv) < 2:
    print('No ticker provided')
    sys.exit()

ticker = sys.argv[1]

url = 'https://finance.yahoo.com/quote/' + ticker + '?p=' + ticker + '&.tsrc=fin-srch'
response = requests.get(url)
try:
    soup = BeautifulSoup(response.text, 'html.parser')
    price = soup.find('body').find(class_='Trsdu(0.3s) Fw(b) Fz(36px) Mb(-4px) D(ib)')
    print('Latest stock price: ' + price.text.strip())
except:
    print('Invalid ticker')