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Internal working of the website

  • Allocate Project

  • Allocate Guides

  • Create a New Project

  • Edit/Delete a Project

  • Generating project wise and guide wise allocation table

Fetch Student Details from Website Using Selenium

I am using a library 'selenium' although this library is also available in other languages like JAVA. This uses the browser to access the internet through a webdriver. Every browser has its own webdriver which can be downloaded using following commands in linux:

sudo apt-get install unzip

wget -N http://chromedriver.storage.googleapis.com/2.26/chromedriver_linux64.zip

unzip chromedriver_linux64.zip

chmod +x chromedriver

sudo mv -f chromedriver /usr/local/share/chromedriver

sudo ln -s /usr/local/share/chromedriver /usr/local/bin/chromedriver

sudo ln -s /usr/local/share/chromedriver /usr/bin/chromedriver

and to install selenium package

python -m pip install selenium
simple example
from selenium import webdriver

driver = webdriver.chrome()
driver.get("https://google.com")

Use of .env files

If we are using sensitive data like passwords with our testing script then is not safe to store them directly in the code, so for keeping them safe we can use environment variables of the system. The .env file contains the key-value pairs for the variables we want to store. The file name starting with ' . ' are hidden so they add another layer as they are not directly visible. We need to import

from dotenv import load_dotenv

load_dotenv() is called to load all variable in the system.
Once loaded we can access them by importing os library as

import os
value = os.envron.get("environment_name")

.find_element() method

T his method is used to locate elements in html file. syntax

driver.find_element(By.ID, 'id')
driver.find_element(By.CLASS_NAME, 'class_name')
driver.find_element(By.CSS_SELECTOR, 'Selector')
driver.find_element(By.LINK_TEXT, 'Link_text')
driver.find_element(By.PARTIAL_LINK_TEXT, 'partial_link')
driver.find_element(By.TAG_NAME, 'tag')
driver.find_element(By.X_PATH, 'path')

Once the element is selected we can press keys using method send_keys()

send_keys() method

This method is used to input data to <input> tag or to press different keys using Keys. The syntax is

from selenium.webdriver.common.keys import Keys

element = driver.find_element(By.ID, 'id')
element.send_keys("keys to be pressed")
element.send_keys(keys.RETURN)
# Other examples

element.send_keys(keys.ADD)
element.send_keys(keys.ARROW_UP)
element.send_keys(keys.ARROW_DOWN)
element.send_keys(keys.TAB)
element.send_keys(keys.COMMAND)
element.send_keys(keys.CONTROL)
element.send_keys(keys.ESCAPE)
element.send_keys(keys.HOME)
element.send_keys(keys.INSERT)
element.send_keys(keys.BACKSPACE)
element.send_keys(keys.CANCEL)

Select() method

Select method throws an exception if the selected element is not a <select> tag. Syntax

from selenium.webdriver.support.select import Select

drop = Select(driver.find_element(By.ID, 'id'))

after pointing the <select> tag we can use select_by_*() methods on the element to select from the <option> tags in the <select> tag. syntax

drop.select_by_index(1)
drop.select_by_value("value_of_option")
drop.select_by_visible_text("The visible text of option")

sleep() method

This method stops the execution of program for the number of seconds passed as argument. Syntax:

import time

time.sleep(10)# this will stop execution for 10 seconds

Django

Installing django

pip install django

Starting django project

django-admin startproject <project_name>

Running project

python manage.py runserver

Creating new app

python manage.py startapp <app_name>

Django does not automatically detect that an app exists. Instead it has to be registered by adding its name to the list of INSTALLED_APPS in your settings.

INSTALLED_APPS = [
    # ...
    'app_name'
]

Create models

from django.db import models
class model_name(models.Model):
    column_name = models.IntegerField()
    # ...

These models represents tables in database. We can use different models fields for various relations.

After creating models we need to run

python manage.py makemigrations

makemigrations - create changes and store them in a file.

python manage.py migrate

migrate - apply the pending changes to database

to execute the changes in database.

Create views

def index(request):
    return HttpResponse("this is dummy text")
urlpatterns = [
    path('index/', views.index, name='index'),
]

In views.py of app, this function will be called if we visit http://127.0.0.1:8000/index/

Create templates

<html>
{% block block_name %}
{% endblock block_name %}
</html>

basically write you html in pieces and join them at time of rendering

{% extends 'base.html' %}

this is used to specify base html file, this base.html file basically contains the basic format of the html page

Create views that actually do something

def index(request):
    return render(request, 'index.html')

this view will return an html page (index.html)

How to handle forms

How to fetch data from tables

How to generate html dynamically

How to input values to tables using the existing data in csv files

Troubleshooting

Error: That port is already in use.

sudo fuser -k 8000/tcp