#+TITLE: StackOverflow #+DATE: 16'th April,2017

• Overview A simple Q&A app using Flask

• Goals To implement StackOverflow like web application which supports most of the features.

• Features

• Create questions and answers.
• Comment on questions and answers.
• Upvote/Downvote questions, answers and comments.
• Users have a profile (With unique gravatar for each user).
• Support for tagging questions.
• Questions are categorized by most recently asked.
• Supports pagination of questions.
• Categorize questions on the basis of answered, unanswered and all.
• Search questions on the basis of tags.

• README ** Getting Started

• These instructions will get you a copy of the project up and running on your local machine for development and testing purposes.

** Prerequisites

Things you need to install the software and instructions to install them:

• You should have python3 and pip3 installed:

• First check if python3 is intstalled by using the command: #+BEGIN_SRC python python3 -V #+END_SRC

• Output: #+BEGIN_SRC Python 3.5.2 #+END_SRC

• If not installed then type the following: #+BEGIN_SRC sudo apt-get update sudo apt-get -y update #+END_SRC ** Instructions for installing pip

#+BEGIN_SRC sudo apt-get install python3-pip

#+END_SRC ** Instructions for installing few more packages and development tools for the programming environment

#+BEGIN_SRC sudo apt-get install build-essential libssl-dev libffi-dev python-dev #+END_SRC ** Installing

• Getting our web app up and running is simple.
• To run it you have to do what you do with most flask apps.

** Setting up virtual environment:

#+BEGIN_SRC virtualenv -p /usr/bin/python3 name_of_your_environment source name_of_your_environment/bin/activate pip install -r requirements.txt #+END_SRC ** Creating the initial database: #+BEGIN_SRC python python db_create.py python db_migrate.py # In case you need to migrate the database #+END_SRC

** Running the web app : #+BEGIN_SRC python python run.py # The web app can be run in http://127.0.0.1:5000 #+END_SRC

** Deployment

• Add additional notes about how to deploy this on a live system

** Built With

• [[http://flask.pocoo.org/][Flask]] - The web framework used
• [[http://getbootstrap.com/][Bootstrap]] - The responsive CSS framework used
• [[https://bootswatch.com/][Bootswatch]] - A website for bootstrap themes
• [[https://flask-wtf.readthedocs.io/en/stable/][Flask-WTF]] - Simple integration of Flask and WTForms, including CSRF, file upload, and reCAPTCHA.
• [[https://flask-login.readthedocs.io/en/latest/][Flask-Login]] - Flask-Login provides user session management for Flask
• [[https://github.com/google/code-prettify][Code-prettify]] - An embeddable script that makes source-code snippets in HTML prettier.

** Versioning

• We used [[https://git-scm.com/][Git]] for versioning.

** License This project is licensed under the MIT License - [[file:LICENSE.md]] ** Acknowledgments

• Special thanks of gratitude to D.R. Venkatesh Choppella for providing us with this excellent oppurtunity to design a web app
• To our mentor Raj Patel without whose help it would have been difficult to complete this project.

• Flask It is a simple web app made using Flask web framework to implement a StackOverflow-like forum site.

• Official Flask documentation [[http://flask.pocoo.org/docs/0.12/][here]].

• How we started ..

• First we started by building database schema.
• Then we built a blueprint of the application like organised controllers and models in different folders of users, comments, etc.
• Then we started coding controllers and models. First we coded models and controllers of users.
• Then we built base.html which is usd in every HTML page.
• Then we started by building controllers and models for login and register page
• Then we coded controllrs and models of comments,answers,tags,etc and side by side coded html.
• Then we made profile page which shows the statastics of the user like number of questions asked,upvotes,downvotes,etc.
• Then we added some intgrity check features that is each user can upvote or downvote only once.
• Then we added some more features like Migration and Pagination.
• At last we added some security features like CSRF protection,captcha generation.
• We also implemented a 404 page error in which will be displayed if someone asks for a page which is not in our web app.

• Design

• Used inheritance feature, for eg. every HTML page inherits from base.html.
• Used SQLAlchemy-migrate to keep track of database updates for us-> Migration feature.
• Used Sqlite database.
• Important feature in our web application is there is a unique gravatar for each user which is generated online when the user successfully registers.
• Pagination is also a feature in our app so that six posts per page is visible.
• Used WTF forms which helps in rendering fields and which also has built in validators.
• Integrity check feature -> One user can only upvote or downvote once.
• Every user can view the dashboard of other user and see his/her statastics which shows number of questions answered,questions asked ,upvotes,downvotes.
• A user can add multiple tags to a particular question and can search question by tags
• Factored our web app into a set of blueprints for making application components and supporting common patterns within an application or across applications.

• Security

• Used SQLALCHEMY prevent SQL injection.
• Used CSRF protction which is auto enabled by WTF forms.
• Another important thing that we had done for security is Captcha generation at the time of registration which the user has to verify. A CAPTCHA (a backronym for "Completely Automated Public Turing test to tell Computers and Humans Apart") is a type of challenge-response test used in computing to determine whether or not the user is human.
• The passowds are stored as hashes not in plain taxt,so even if our database is stolen by someone else he/she cannot get the password used for login into our web app.

• Snippets ** Snippet of schema #+BEGIN_SRC text User:

• Name => String
• Age => String
• Year Joined => String
• Reputation => Integer
• Id (Primary Key) => Integer

#+END_SRC ** Snippet of Blueprint #+BEGIN_SRC python from .mod_answer import mod_answer as answer_blueprint app.register_blueprint(answer_blueprint)

from .mod_auth import mod_auth as auth_blueprint app.register_blueprint(auth_blueprint)

from .mod_comment import mod_comment as comment_blueprint app.register_blueprint(comment_blueprint)

from .mod_home import mod_home as home_blueprint app.register_blueprint(home_blueprint) #+END_SRC ** Snippet of views.py(controller) of login page #+BEGIN_SRC python @mod_auth.route('/login', methods = ['GET', 'POST']) def login(): form = LoginForm() if form.validate_on_submit(): user = User.query.filter_by(email = form.email.data).first() if user is not None and user.verify_password(form.password.data): login_user(user) return redirect(url_for('mod_user.dashboard')) else: flash('Invalid email or password.') return render_template('mod_auth/login.html', form = form, title = 'Login')

#+END_SRC ** Snippet of WTF FORMS #+BEGIN_SRC html

Post Question

#+END_SRC