Python - Flask - miniapp - ignite

FLASK - ÚVOD DO PYTHONU

MICHAL HATÁK

INTRO

DIFFERENCES BETWEEN PHP AND PYTHON

▸ whitespace significant

▸ library for everything

▸ full language (not only websites)

▸ module system

INTRO

PACKAGE SYSTEM

▸ PIP - very similar to composer

▸ pip install <package name>

▸ pip install -f <requirements.txt>

INTRO

VIRTUAL ENVIRONMENTS

▸ isolated python environment

▸ contains python executables > multiple python version on one system

INTRO

THE GOAL

▸ basic web app using Flask framework (very similar to Nette)

▸ little showcase

PREPARE PROJECT

FIRST STEPS

▸ create virualenv $ virtualenv venv$ . venv/bin/activate

▸ install Flask framework $ pip install Flask

#1

APP.PY

from flask import Flask

app = Flask(__name__)

@app.route('/') def hello_world(): return 'Hello World!'

if __name__ == '__main__': app.debug = True app.run() # default 127.0.0.1:5000

#2

APP.PY

from flask import Flask, render_template


@app.route('/hello/<name>') def hello(name): return render_template("hello.html", name=name)

if __name__ == '__main__': app.debug = True app.run() # default 127.0.0.1:5000

TEMPLATES/HELLO.HTML

<!DOCTYPE html> <html lang="en"> <head> <title>My First Website</title> </head> <body> Hello <strong>{{ name }}</strong> Hello <strong>{{ name | reverse }}</strong> {{ "%s - %s" | format("Hello", name) }} </body> </html>

#3

INSTALL

▸ $ pip install wtforms flask-wtf

TEMPLATES/LAYOUT.HTML

<!DOCTYPE html> <html lang="en"> <head> <title>My First Website</title> </head> <body> {% with messages = get_flashed_messages() %} {% if messages %} <ul class=flashes> {% for message in messages %} <li>{{ message }}</li> {% endfor %} </ul> {% endif %} {% endwith %}

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

FORMS.PY

from flask_wtf import Form from wtforms import StringField, SubmitField, validators

class GreetingsForm(Form): name = StringField(label="Enter your name: ", validators=[validators.DataRequired()]) submit = SubmitField("Greet!")

APP.PY

from flask import (Flask, render_template, request, flash, redirect, url_for)

from forms import GreetingsForm


@app.route('/hello-form', methods=["GET", "POST"]) def hello_form(): form = GreetingsForm(request.form)

if form.validate_on_submit(): flash("Hello" + form.name.data) return redirect(url_for("hello_form"))

return render_template("hello-form.html", form=form)

TEMPLATES/HELLO-FORM.HTML

{% extends "layout.html" %} {% block body %} <form method="post" action="{{ url_for("hello_form") }}"> {{ form.hidden_tag() }}

<label>{{ form.name.label.text }}</label> {{ form.name() }}

{{ form.submit() }} </form> {% endblock %}

Software

Python - Flask - miniapp - ignite