Python master class part 1
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This document provides an introduction and overview of Python and the Flask web framework. It discusses key Python concepts like objects, references, memory management and data types. It also covers Flask topics like routing, templates, request objects, sessions and authentication. The document aims to give readers a high-level understanding of Python and how to build basic web applications with Flask.
![also,
z = [110, 110]
110
x
y
Reference count: 4](https://image.slidesharecdn.com/pythonmasterclasspart1-160804103145/85/Python-master-class-part-1-28-320.jpg)
![from flask import request
@app.route('/login', methods=['GET', 'POST'])
def login():
if request.method == 'POST':
do_the_login()
else:
show_the_login_form()](https://image.slidesharecdn.com/pythonmasterclasspart1-160804103145/85/Python-master-class-part-1-63-320.jpg)
![Request Object
from flask import request
@app.route('/login', methods=['POST', 'GET'])
def login():
error = None
if request.method == 'POST':
if valid_login(request.form['username'],
request.form['password']):
return log_the_user_in(request.form['username'])
else:
error = 'Invalid username/password'
# the code below is executed if the request method
# was GET or the credentials were invalid
return render_template('login.html', error=error)](https://image.slidesharecdn.com/pythonmasterclasspart1-160804103145/85/Python-master-class-part-1-67-320.jpg)
![from flask import Flask, session, redirect, url_for, escape, request
app = Flask(__name__)
@app.route('/')
def index():
if 'username' in session:
return 'Logged in as %s' % escape(session['username'])
return 'You are not logged in'
@app.route('/login', methods=['GET', 'POST'])
def login():
if request.method == 'POST':
session['username'] = request.form['username']
return redirect(url_for('index'))
return ''' <form action="" method="post">
<p><input type=text name=username>
<p><input type=submit value=Login>
</form>
'''](https://image.slidesharecdn.com/pythonmasterclasspart1-160804103145/85/Python-master-class-part-1-69-320.jpg)
![@app.route('/logout')
def logout():
# remove the username from the session if it's there
session.pop('username', None)
return redirect(url_for('index'))
# set the secret key. keep this really secret:
app.secret_key = 'A0Zr98j/3yX R~XHH!jmN]LWX/,?RT'](https://image.slidesharecdn.com/pythonmasterclasspart1-160804103145/85/Python-master-class-part-1-70-320.jpg)
Python master class part 1
- 1. Python Master Class Part 1 By Chathuranga Bandara www.chathuranga.com
- 2. Todayâs Agenda Introduction to Python Introduction to Flask
- 3. Python
- 4. What is Python⊠really.. Multi Purpose Object Oriented Interpreted? Dynamically Typed and Strong as well Readability and We are Adults!
- 5. Features Cross Platform Functional Support as well Everything is an Object Many Implementations Batteries Included
- 7. Why Python?
- 11. Some TaxâŠ. i mean Syntax..
- 12. Indentation is the Key!
- 15. Types?
- 16. Not Strongly Typed What the f*** that means?
- 17. Letâs Discuss Python Memory Management.
- 18. What is a C type Variable?
- 19. Variable location value a 0x3FS 101 b 0x3F9 101 unique location These values live in a fixed size bracket hence can only hold same sized data or an overflow happens
- 20. When we change one value Variable location value a 0x3FS 110 b 0x3F9 101 Data in the memory location get overwritten
- 21. Python has Names not Variables
- 23. Name is just a label for an object In Python you can have multiple names for a single object
- 24. What is a reference? Name or a container pointing to an object
- 25. ie: 110 x = 110 x +1 reference count
- 26. 110 x = 110 y = 110 x +2 reference count y
- 27. Not sure?
- 28. also, z = [110, 110] 110 x y Reference count: 4
- 29. Decrease Ref count? 110 x reference count: 1 y del will not delete the object but rather delete the reference to the object.
- 30. What happens when the ref count is 0? Then it will delete the object. (what the garbage collector does in python)
- 31. Different types of objects then? â Numbers â Strings â dict â list â classes
- 32. Because of names
- 34. Functions also can have names
- 35. Strings
- 36. Numbers
- 37. None is the new null
- 38. Lists
- 40. Dictionaries
- 41. Mutable vs Immutable Mutable : can alter â list, dict, byte array, set Immutable: otherwise â Numbers, string, tuples, frozen sets
- 43. Much efficient
- 44. Control Flows - Conditionals
- 45. Loops
- 46. Functions
- 48. CLASSES
- 50. What is PIP? pip is the Python package index
- 51. $ sudo apt-get install python-pip
- 53. $ pip install virtualenv $ cd my_project_folder $ virtualenv name_of_the_virt $ source name_of_the_virt/bin/activate $ do pip sh*t $ deactivate
- 54. Good practice! Have a folder in root called requirements and inside that have following: â dev.txt â Prod.txt
- 55. Ie: dev.txt
- 56. $ pip install -r requirements/dev.txt
- 57. pip install Flask # Import Flask library from flask import Flask # Initialize the app from Flask app = Flask(__name__) # Define a route to hello_world function @app.route('/hello') def hello_world(): return 'Hello World Again!' # Run the app on http://localhost:8085 app.run(debug=True,port=8085) python hello.py
- 60. Routing @app.route('/') def index(): return 'Index Page' @app.route('/hello') def hello(): return 'Hello, World'
- 61. Variables? @app.route('/user/<username>') def show_user_profile(username): # show the user profile for that user return 'User %s' % username @app.route('/post/<int:post_id>') def show_post(post_id): # show the post with the given id, the id is an integer return 'Post %d' % post_id
- 62. That is sweet, what about the REST?
- 63. from flask import request @app.route('/login', methods=['GET', 'POST']) def login(): if request.method == 'POST': do_the_login() else: show_the_login_form()
- 64. Rendering Templates from flask import render_template @app.route('/hello/') @app.route('/hello/<name>') def hello(name=None): return render_template('hello.html', name=name)
- 65. Where the f**k is the template then?
- 66. <!doctype html> <title>Hello from Flask</title> {% if name %} <h1>Hello {{ name }}!</h1> {% else %} <h1>Hello, World!</h1> {% endif %}
- 67. Request Object from flask import request @app.route('/login', methods=['POST', 'GET']) def login(): error = None if request.method == 'POST': if valid_login(request.form['username'], request.form['password']): return log_the_user_in(request.form['username']) else: error = 'Invalid username/password' # the code below is executed if the request method # was GET or the credentials were invalid return render_template('login.html', error=error)
- 68. sessions
- 69. from flask import Flask, session, redirect, url_for, escape, request app = Flask(__name__) @app.route('/') def index(): if 'username' in session: return 'Logged in as %s' % escape(session['username']) return 'You are not logged in' @app.route('/login', methods=['GET', 'POST']) def login(): if request.method == 'POST': session['username'] = request.form['username'] return redirect(url_for('index')) return ''' <form action="" method="post"> <p><input type=text name=username> <p><input type=submit value=Login> </form> '''
- 70. @app.route('/logout') def logout(): # remove the username from the session if it's there session.pop('username', None) return redirect(url_for('index')) # set the secret key. keep this really secret: app.secret_key = 'A0Zr98j/3yX R~XHH!jmN]LWX/,?RT'
- 71. Thatâs all for today Folks!