flask-full-study: A Python repository from lucasfonsecads

Flask Full Study

Here we'll abordding all recurses of flask with start one simple appication's - 'Hello World' to a full api prroject.

virtualenv env
cd env
source bin/activate

Requirements

(env) pip install flask

Determine your public folder:

app = Flask(__name__, static_folder='public/assets')
#one example to access the folder public and assets before

Example to create one app flask:

import flask
from flask import Flask

app = Flask(__name__)

Example to access one route and use Jinja2 to render:

@app.route('/')
def index():
  return '<h1>Hello World</h1>

Example to render one template wiht Jinja2:

@app.route('/template')
def renderT():
  return render_template('index.html')
#remember to import render_template from flask

Example do redirect one access:

@app.route('/redirect')
def redirecT():
  return redirect('https://github.com/lucasfonmiranda')
#remeber to import redirect from flask

Example to determine web server:

if __name__ == '__main__':
  app.run(host='0.0.0.0', port = 4000)

For run your app:

python run.py

Jinja2 Section

Jinja2 offers several control structures can be used to alter the flow od the template.
The following example shows how conditional statements can be entered in a template:

{% if user %}
  Hello, {{ user }}!
{% else %}
  Hello stranger!
{% endif %}

Another common need in templates is to render a list of elements:

<ul>
  {% for comment in comments %}
  <li>{{ comment }}</li>
  {% endfor %}
</ul>

Using bootstrap framework from Twitter with flask:

Requirements:

(env) pip install flask-bootstrap

Import Bootstrap for your flask application:

from flask_bootstrap import Bootstrap

boostrap = Boostrap(app)

For see one page using bootstrap go in templates/base.html run your app and access localhost/bootstrap and see the magic...

Web Forms

Requirements:

(env) pip install flask-wtf

Cross-Site Request Forgery(CSRF) Protection:

A CSRF attack occurs when a malicious website sends requests to a different website on which the victim is logged in. By default, Flask-WTF protects all forms against CSRF attacks.

To implement CSRF proteciton:

app = Flask(__name__)
app.config['SECRET_KEY'] = 'hard string'

For generate one key in python command line:

from os import urandom
from base64 import b64encode
import os

random = os.urandom(64)
key = b64encode(random).decode('utf-8')
print (key)

First function use Web Forms:

@app.route('/forms', methods=['GET', 'POST']) #example to use the methods GET and POST
def formsIndex():
	name = None
	form = NameForm()
	if form.validate_on_submit():
		name = form.name.data
		form.name.data = ''
	return render_template('newindex.html', form=form, name=name)

Function with flash alert for changed names and storage the last name in variable:

@app.route('/msg', methods=['GET', 'POST']) #New function to try flash message
def msgTest():
  form = NameForm()
  if form.validate_on_submit():
    old_name = session.get('name')
    if old_name is not None and old_name != form.name.data:
      flash('You have changed your name!')
    session['name'] = form.name.data
    form.name.data = ''
  return render_template('newindex.html', form = form, name= session.get('name'))

SQL Databases

A database stores application data in an organized way. The application then issues queries to retrieve specific portions as they are needed. The most commonly ysede databases for web applications are those based on the relational model, also called SQL databases in reference to the Structured Query Language they use.

Python has packages for most database engines, Flask puts no restrictions on what database packages can be used. You can use MySQL, Postgres, SQLite and others. Here we gonna use SQLAlchemy.

Requirements:

(env) pip install flask-sqlachemy

lucasfonsecads/flask-full-study

Flask Full Study

Jinja2 Section

Using bootstrap framework from Twitter with flask:

Web Forms

SQL Databases