17 KiB
PyConES17
Workshop: Flask-wallapop-watcher (Application to monitor prices in Wallapop)
Taller: Flask-wallapop-watcher (Aplicación para vigilar precios en Wallapop)
Demo
Currently implemented on a real site:
Actualmente esta implementado en un sitio real:
Run (Ejecutar)
For the impatient, you can play with the finished exercise. You should download the code and execute the following commands.
Para los impacientes, podéis jugar con el ejercicio acabado. Debéis descargar el código y ejecutar los siguientes comandos.
cd flask-wallapop-watcher
pip3 install virtualenv
virtualenv --python=python3 .venv
source .venv/bin/activate
pip3 install -r requirements.txt
python3 app.py
Then open in your favorite browser, which will possibly be the fantastic Firefox, a new tab with http://127.0.0.1:5000
Después abrir en tu navegador favorito, que posiblemente será el fantástico Firefox, una pestaña nueva con http://127.0.0.1:5000
Workshop (Taller)
Minimum requirements (Requisitos mínimos)
- python3
- wget
- Editor de texto enriquecido: Vim, Sublime Text, VSCode, Atom...
- sqlite3
- Conexión a internet
We checked everything (Comprobamos que tenemos todo)
python3 --help
wget --help
sqlite3 --help
ping -c 5 google.com
Part 1 - Flask Core y Search (Parte 1 - Nucleo de Flask y Buscador) 50 min
1.1 Ready?
We prepare our virtual environment.
Preparamos nuestro entorno virtual.
mkdir flask-wallapop-watcher
cd flask-wallapop-watcher
pip3 install virtualenv
virtualenv --python=python3 .venv
source .venv/bin/activate
wget https://raw.githubusercontent.com/tanrax/flask-wallapop-watcher/master/requirements.txt
pip3 install -r requirements.txt
1.1 Hello PyConES17
Template Flask. We created a new file called app.py.
Plantilla Flask. Creamos un nuevo archivo llamado app.py.
from flask import Flask
# Flask
app = Flask(__name__)
app.config['DEBUG'] = True
app.config['SECRET_KEY'] = 'mi secreto'
@app.route('/')
def buscador():
return 'Hello PyConES17 !!!'
if __name__ == '__main__':
app.run()
We run and check that everything works.
Ejecutamos y comprobamos que todo funciona.
python3 app.py
http://127.0.0.1:5000
1.2 Templates
We created a folder called templates. Inside we make two more folders: layouts and items. In layouts we will make a new one with the name master.html.
Creamos una carpeta llamada templates. Dentro dos más: layouts y items. En layouts haremos uno nuevo con el nombre master.html.
<!DOCTYPE html>
<html lang="es">
<head>
<title>{% block title %}{% endblock %} | Vigilador de Wallapop</title>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://bootswatch.com/superhero/bootstrap.css">
</head>
<body>
<div class="container">
<ul class="nav nav-pills nav-justified">
<li role="presentation" {% if active_page == "buscador" or not active_page %}class="active"{% endif %}><a href="">Buscador</a></li>
<li role="presentation" {% if active_page == "programadas" %}class="active"{% endif %}><a href="#">Programadas</a></li>
</ul>
{% block body %}{% endblock %}
</div>
</body>
</html>
In items we are going to have our first real page that will inherit from master.html. Within items we create searcher.html.
En items vamos a tener nuestra primera página real que va a heredar de master.html. Dentro de items creamos buscador.html.
{% extends 'layouts/master.html' %}
{% set active_page = "buscador" %}
{% block title %}Buscador{% endblock %}
{% block body %}
<h1>Buscador</h1>
{% endblock %}
You update app.py to work with our template engine.
Actulizamos app.py para que trabaje nuestro motor de plantillas.
from flask import Flask, render_template
# Flask
app = Flask(__name__)
app.config['DEBUG'] = True
app.config['SECRET_KEY'] = 'mi secreto'
@app.route('/')
def buscador():
return render_template('items/buscador.html')
if __name__ == '__main__':
app.run()
We create the second page where we will have our searches stored. Within items we create a new file with the name of programadas.html.
Creamos la segunda página donde tendremos nuestras busquedas almacenadas. Dentro de items creamos un fichero nuevo con el nombre de programadas.html.
{% extends 'layouts/master.html' %}
{% set active_page = "programadas" %}
{% block title %}Programadas{% endblock %}
{% block body %}
<h1>Soy la página donde estará las programadas</h1>
{% endblock %}
We update app.py with the new page.
Actulizamos app.py con la nueva página.
from flask import Flask, render_template
# Flask
app = Flask(__name__)
app.config['DEBUG'] = True
app.config['SECRET_KEY'] = 'mi secreto'
@app.route('/')
def buscador():
return render_template('items/buscador.html')
@app.route('/programadas')
def programadas():
return render_template('items/programadas.html')
if __name__ == '__main__':
app.run()
As a final detail we will make our browser buttons have the correct routes.
Como último detalle haremos que nuestros botones del navegador tengan las rutas correctas.
<!DOCTYPE html>
<html lang="es">
<head>
<title>{% block title %}{% endblock %} | Vigilador de Wallapop</title>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://bootswatch.com/superhero/bootstrap.css">
</head>
<body>
<div class="container">
<ul class="nav nav-pills nav-justified">
<li role="presentation" {% if active_page == "buscador" or not active_page %}class="active"{% endif %}><a href="{{ url_for('buscador') }}">Buscador</a></li>
<li role="presentation" {% if active_page == "programadas" %}class="active"{% endif %}><a href="{{ url_for('programadas') }}">Programadas</a></li>
</ul>
{% block body %}{% endblock %}
</div>
</body>
</html>
1.3 Forms
We make the new file forms.py.
Realizamos el nuevo archivo forms.py.
from flask_wtf import FlaskForm
from wtforms import StringField, IntegerField
from wtforms.validators import DataRequired, Length, NumberRange, Optional
class SearchForm(FlaskForm):
name = StringField('Nombre', [Length(min=1, max=100, message='Es demasiado largo'), DataRequired(message='Campo obligatorio')])
price_max = IntegerField('Precio', [NumberRange(1, message='No puede ser inferior a 1'), Optional()])
We load it and pass it to the template.
Lo cargamos y se lo pasamos a la plantilla.
from flask import Flask, render_template
from forms import SearchForm
# Flask
app = Flask(__name__)
app.config['DEBUG'] = True
app.config['SECRET_KEY'] = 'mi secreto'
@app.route('/', methods=['GET', 'POST'])
def buscador():
form = SearchForm()
if form.validate_on_submit():
pass
return render_template('items/buscador.html', form=form)
@app.route('/programadas')
def programadas():
return render_template('items/programadas.html')
if __name__ == '__main__':
app.run()
We print the fields with a loop in our template buscador.html.
Imprimimos los campos con un bucle en nuestra plantilla buscador.html.
{% extends 'layouts/master.html' %}
{% set active_page = "buscador" %}
{% block title %}Buscador{% endblock %}
{% block body %}
<h1>Buscador</h1>
<div class="row">
<div class="col-xs-12">
<form method="post">
{{ form.csrf_token }}
{% for input in form %}
{% if input.type != 'CSRFTokenField' %}
<div class="form-group">
{# Label #}
{{ input.label }}
{# Input #}
{{ input(class="form-control") }}
{# Errors #}
{% if input.errors %}
<div class="has-error">
{% for error in input.errors %}
<label class="help-block">
{{ error }}
</label>
{% endfor %}
</div>
{% endif %}
</div>
{% endif %}
{% endfor %}
<input type="submit" class="btn btn-primary" value="Buscar">
</form>
</div>
</div>
{% endblock %}
1.4 Search
It's time for fun. First we update our app.py to get the form data if you pass the validations. Then, with that information, we will make a call to the Wallapop API. We will only need the URL that they use in your APP. With urllib3 we will have all the results in a simple dictionary. Which is great, since it is easy to iterate within our template.
Ha llegado la hora de lo divertido. Primero actulizamos nuestro app.py para obtener los datos del formulario si pasa las validaciones. Después, con esa información, haremos una llamada al API de Wallapop. Solo necesitaremos la URL que utilizan en su APP. Con urllib3 tendremos todos los resultados en un sencillo diccionario. Lo cual es magnífico, ya que es fácil de iterar dentro de nuestra plantilla.
from flask import Flask, render_template, request
from forms import SearchForm
# Get data Wallapop
import json
from urllib3 import PoolManager
import urllib.parse
# Flask
app = Flask(__name__)
app.config['DEBUG'] = True
app.config['SECRET_KEY'] = 'mi secreto'
@app.route('/', methods=['GET', 'POST'])
def buscador():
form = SearchForm()
results = None
if form.validate_on_submit():
name = form.name.data
price_max = form.price_max.data or ''
# Search in Wallapop
results = get_resultados(name, price_max)
return render_template('items/buscador.html', form=form, results=results)
@app.route('/programadas')
def programadas():
return render_template('items/programadas.html')
def get_resultados(name='', price_max=''):
http = PoolManager()
url_api = 'http://es.wallapop.com/rest/items?minPrice=&maxPrice={price_max}&dist=&order=creationDate-des&lat=41.398077&lng=2.170432&kws={kws}'.format(
kws=urllib.parse.quote(name, safe=''),
price_max=price_max
)
results = http.request('GET', url_api)
results = json.loads(
results.data.decode('utf-8')
)
return results['items']
if __name__ == '__main__':
app.run()
And in our template of buscador.html.
Y en nuestra plantilla de buscador.html.
{% extends 'layouts/master.html' %}
{% set active_page = "buscador" %}
{% block title %}Buscador{% endblock %}
{% block body %}
<h1>Buscador</h1>
<div class="row">
<div class="col-xs-12">
<form method="post">
{{ form.csrf_token }}
{% for input in form %}
{% if input.type != 'CSRFTokenField' %}
<div class="form-group">
{# Label #}
{{ input.label }}
{# Input #}
{{ input(class="form-control") }}
{# Errors #}
{% if input.errors %}
<div class="has-error">
{% for error in input.errors %}
<label class="help-block">
{{ error }}
</label>
{% endfor %}
</div>
{% endif %}
</div>
{% endif %}
{% endfor %}
<input type="submit" class="btn btn-primary" value="Buscar">
</form>
</div>
</div>
{% if results %}
<table class="table">
{% for item in results %}
<tr>
<td><img class="img-responsive" src="{{ item.pictureURL }}" alt="{{ item.title }}"></td>
<td>{{ item.title }}</td>
<td>{{ item.price }}</td>
<td><a href="#" class="btn btn-success">+</a></td>
</tr>
{% endfor %}
</table>
{% endif %}
{% endblock %}
And ... Voilá.
Y... Voilá.
Break (Descanso) - 10 min
We debug bugs and prepare for the next point.
Depuramos bugs y nos preparamos para el siguiente punto.
Part 2 - Databases and CRUD with Flask (Bases de datos y CRUD elementos con Flask)
Break (Descanso) - 10 min
We take air for the last part. Otherwise, we make as we go to the bathroom and do not come back.
Cogemos aire para la última parte. En caso contrario, hacemos como que vamos al baño y nos piramos.