CSCI 2133 Rapid Programming Techniques for Innovation A Python - - PowerPoint PPT Presentation

CSCI 2133

CSCI 2133 – Rapid Programming Techniques for Innovation

A Python based framework Django Crash Lesson

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Previous Lecture

• Python Data Manipulation

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Agenda

• Django Overview
• Learn Django by examples
• http://docs.python.org
• https://docs.djangoproject.com

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Why Django

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• ORM
• Automatic admin

interface

• Regex-based URLdesign
• T

emplating system

• Cacheinfrastructure
• Internationalization
• Command-line job

framework

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Lets get started

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django-admin startproject myshop

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It starts to work immediately

• python manage.py runserver

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Wher ere e those v e views come f e from

• First of all, download a suitable IDE to view files

under project:

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Add a home page

python m manage.py star artap app home me

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Create a template

• M a k e a t e m p l a t e s d i r e c t o r y u n d e r h o m e :

m k d i r t e m p l a t e s

• P u t a n H T M L fi l e i n t h e t e m p l a t e s d i r e c t o r y

W e b u i l t a v e r y s i m p l e h t m l p a g e c a l l e d “ h o m e . h t m l ”

• A d d a “ u r l s . p y ” u n d e r h o m e , a n d i n c l u d e i t i n y o u r r o o t

u r l s . p y

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from django.contrib import admin from django.urls import path, include urlpatterns = [ path('admin/', admin.site.urls), path('', include('home.urls', namespace='home')), ]

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Fill in views.py and urls.py under “home” app

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from django.http import HttpResponse from django.template.loader import render_to_string def base(request): rendered = render_to_string('base.html') return HttpResponse(rendered)

Views.py is the web UI interface to help Django find template.

from django.conf.urls import url from . import views app_name = 'home' urlpatterns = [ url(r'^$', views.base, name='base'), ]

Urls.py is the configuarion file to route the http request to corresponding temaple (here we refer to the base function in views.py). And base function points at the template we specified.

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Final working home structure

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Lab and Exercises

• Create a template for the homepage
• Create a view that will respond with the rendered

template

• Connect the / URL to the view
• You could refer to

https://git.cs.dal.ca/gang/django-tutorials as example.

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Agenda

• Django REST connection
• Twitter API demo
• Django templates language

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Django consume REST service

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• Using cURL

cURL (pronounced 'curl') is a computer software project providing a library and command-line tool for transferring data using various protocols. The cURL project produces two products, libcurl and cURL. It was first released in 1997. The name stands for "Client URL".The original author and lead developer is the Swedish developer Daniel Stenberg.

• ------------------- from wiki
• curl is a command-line tool for transferring data

and supports about 22 protocols including

• HTTP. This combination makes it a very good ad-

hoc tool for testing our REST services.

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Com Command-line O Options

• Verbose:

curl -v https://web.cs.dal.ca/~gang/csci2133-project/step-db/login- all.php

• Output

curl -o out.json https://web.cs.dal.ca/~gang/csci2133-project/step- db/login-all.php

• HTTP Methods with curl

Get Same as output

curl -o https://web.cs.dal.ca/~gang/csci2133-project/step-db/login-rest- service.php? username=test1&password=12345

Post

curl -d 'username=test1&password=12345' https://web.cs.dal.ca/~gang/csci2133-project/step-db/login-rest- service.php [{"cus_num":11,"username":"test1","email":"test1@company.com"}]

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Continue…

• PUT

curl -d @request.json -H 'Content-Type: application/json’ -X PUT http://localhost:8082/spring-rest/foos/9

• DELETE

curl -X DELETE http://localhost:8082/spring-rest/foos/9

• Authentication

If 401 – Unauthorized HTTP response code and an associated WWW-Authenticate header: curl --user baeldung:secretPassword http://example.com/

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Combine with Python

• The easiest way to execute curl in python like this:

import os

• s.system("curl -v.........")

But the result depends on work environment. Somehow exception happens, such as “curl command not found” Next.... Let us find elegant way.

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Using module “Request”

• GET

From

curl -v https://web.cs.dal.ca/~gang/csci2133-project/step- db/login-all.php

To

import requests response = requests.get('https://web.cs.dal.ca/~gang/csci2133- project/step-db/login-all.php')

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• POST

From

curl -d 'username=test1&password=12345' https://web.cs.dal.ca/~gang/csci2133-project/step-db/login-rest- service.php

To

import requests data = { 'username': 'test1', 'password': '12345' } response = requests.post('https://web.cs.dal.ca/~gang/csci2133- project/step-db/login-rest-service.php', data=data)

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• Delete

From

curl -X DELETE http://localhost:8082/spring-rest/foos/9

To

import requests response = requests.delete('http://localhost:8082/spring- rest/foos/9')

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A sample code of posting Rest

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import requests data = { 'username': 'test1', 'password': '12345' } response = requests.post('https://web.cs.dal.ca/~gang/csc i2133-project/step-db/login-rest-service.php', data=data) print(response.json())

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Twitter Connection

• Get client Key and Secret from Twitter

Generate Access Token to Authenticate ( aka Login) to Twitter API Once this is done you will need to get:

• Consumer Key (API Key)
• Consumer Secret (API Secret)
• Access Token
• Access Token Secret
• Oauth2 authentication

import base64 import requests client_key = ‘Y**********9' client_secret = 'Bsqx*********ExI' key_secret = '{}:{}'.format(client_key, client_secret).encode('ascii') b64_encoded_key = base64.b64encode(key_secret) b64_encoded_key = b64_encoded_key.decode('ascii')

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• The next step is to make a post request to the authentication

endpoint to obtain a Bearer Token to be included in subsequent API requests.

base_url = 'https://api.twitter.com/' auth_url = '{}oauth2/token'.format(base_url) auth_headers = { 'Authorization': 'Basic {}'.format(b64_encoded_key), 'Content-Type': 'application/x-www-form-urlencoded;charset=UTF-8' } auth_data = { 'grant_type': 'client_credentials' } auth_resp = requests.post(auth_url, headers=auth_headers, data=auth_data, verify=False) print(auth_resp.json()) access_token = auth_resp.json()['access_token']

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Making Q Quer eries es t through t twi witter er

• The reference documentation for the API can be

found at: https://dev.twitter.com/rest/reference

• We will be making a search request for the latest 2

tweets with the terms ‘General Election’.

• The options for search parameters can be found at:

https://dev.twitter.com/rest/reference/get/search/t weets

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Get first 2 tweets by using access_token

25 search_headers = { 'Authorization': 'Bearer {}'.format(access_token) } search_params = { 'q': 'General Election', 'result_type': 'recent', 'count': 2 } search_url = '{}1.1/search/tweets.json'.format(base_url) search_resp = requests.get(search_url, headers=search_headers, params=search_params, verify=False) tweet_data = search_resp.json() for x in tweet_data['statuses']: print(x['text'] + '\n')

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Exercise

• Playback generation of last 2 tweets by yourself.

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Django templates

• Views.py
• Http request/response modules
• Integrate with template file
• Templates languages:
• Variables
• Condition
• Loop

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Combine with Django

import requests from django.http import HttpResponse def base(request):

data = {

'username’: request.GET[‘username’], 'password’: request.GET[‘password’]

} response = requests.post('https://web.cs.dal.ca/~gang/csci2133-project/step-db/login-rest-service.php', data=data) django_response = HttpResponse( content=response.content, status=response.status_code, content_type=response.headers['Content-Type'] )

return django_response

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Views.py matters http service call

• In Django, views have to be created in the app

views.py file:

from django.http import HttpResponse def hello(request): text = """<h1>welcome to my app !</h1>""" return HttpResponse(text)

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HttpRequest and HttpResponse

• Views.py always takes HttpRequest as first

parameter.

• Several important HttpRequest members:
• HttpRequest.scheme
• HttpRequest.GET / HttpRequest.POST

Example: request.GET[‘key’] / request.POST[‘key’]

• HttpRequest.method

Example: if request.method == ‘GET’

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Continue..

• HttpResponse objects
• In contrast to HttpRequest objects, which are created

automatically by Django, HttpResponse objects are your responsibility. Usage:

from django.http import HttpResponse >>> response = HttpResponse("Here's the text of the Web page.") >>> response = HttpResponse("Text only, please.", content_type="text/plain")

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Now talk with your template

• Instead of hard code response text in views.py

from django.shortcuts import render def base(request): return render(request, “base.html", {})

• Combine with what we learn from Python REST

service call.

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Continue…

33 import requests from django.http import HttpResponse from django.shortcuts import render def base(request): data = { 'username': request.GET.get('username'), 'password': request.GET.get('password') } response = requests.post('https://web.cs.dal.ca/~gang/csci2133-project/step- db/login-rest-service.php', data=data) respData = response.json() print(respData) html = render(request, 'base.html', {"theUser" : respData, "title": "track a user", "h2": "Search Result"}) return HttpResponse(html)

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Template

• Your template should be always located in

templates folder under your app.

• Catch the variable from views.py

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Template languages

• Filters
• They help you modify variables at display time. Filters structure

looks like the following: {{var|filters}}.

• Some examples −
• {{string|truncatewords:80}}
• {{string|lower}}
• Tags
• Tags lets you perform the following operations: if condition, for

loop, template inheritance and more.

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Tags

• IF

Example:

{% if theUser|length < 1 %} <h5>No Result!</h5> {% elif %} ….. {% endif %}

• FOR

<table> {% for user in theUser %} <tr> {% for key,value in user.items %} <td> {{value}} </td> {% endfor %} </tr> {% endfor %} </table>

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Playback

• Templates file: https://git.cs.dal.ca/gang/django-

tutorials/blob/master/home/templates/base.html

• Views.py: https://git.cs.dal.ca/gang/django-

tutorials/blob/master/home/views.py

• Create an Django app on your local, access service

https://web.cs.dal.ca/~gang/csci2133-project/step- db/login-rest-service.php by using GET method to send username and password. Display result on web.

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Models

• Database setup
• Create Models in App
• Manipulate Data through Models

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How models benefit your dev

• An ORM allows for simple manipulation of data

without having to write complex SQL

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Pictures credit to https://djangobook.com/mdj2-models/

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So benefits of modals are:

• Simplicity.
• Consistency.
• Avoids Introspection.
• Version Control.
• Advanced Metadata.

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How modals work in Django

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Pictures credit to https://djangobook.com/mdj2-models/

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Moreover…

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Pictures credit to https://djangobook.com/mdj2-models/

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Lets get our feet wet

• Follow simple steps to have your own models:
• Configure database engine in settings.py
• Create a py class in a file called models.py in your app
• Update underlying DB by “migration” command
• That is it…

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Configure database engine in settings.py

• If you are not using SQLite as your database, additional settings

such as USER, PASSWORD, HOST must be added. For more details, see the reference documentation for DATABASES.

DATABASES = { 'default': { 'ENGINE': 'django.db.backends.mysql', 'NAME': 'DB_NAME', 'USER': 'DB_USER', 'PASSWORD': 'DB_PASSWORD', 'HOST': 'localhost', # Or an IP Address that your DB is hosted on 'PORT': '3306', } }

You might want to install DB module if your python doesn’t have:

pip3 install mysqlclient If you fail command above, try old version: pip install mysqlclient==1.3.12

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Now create a class in models.py

• Supposedly I want to create a teacher table ( you

don’t have to directly miniplate database), instead you create model class in Django:

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from django.db import models # Create your models here. class TeacherB0012345(models.Model): name = models.CharField(max_length=100) address = models.CharField(max_length=100, blank=True) city = models.CharField(max_length=50) province = models.CharField(max_length=2) email = models.EmailField(max_length=100, blank=True) class Meta: verbose_name_plural = 'Teacher' class CourseB0012345(models.Model): teacher = models.ForeignKey(TeacherB0012345, on_delete=models.CASCADE) name = models.CharField(max_length=42) code = models.CharField(max_length=4) website = models.URLField(max_length=200, null=True, blank=True) content = models.TextField() last_update = models.DateTimeField(auto_now_add=True)

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Now run migrate command

• First, we must package up our model changes into

individual migration files using the command

• makemigrations. :

python manage.py makemigrations

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Finally you can commit your changes to DB

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Now double check changes in DB

• https://www.db4free.net/phpMyAdmin

user="csci2133_gang", passwd="12345678",

• Note: the generated table name by Django will be

formed by “app name” + “_” + “class name in models”

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Exercise in Class

Giving the database connection:

host="db4free.net", user="csci2133_gang", passwd="12345678", database="csci2133_login“

Please create a class (name is student_[your banner id]) in your models.py, and this class will be mapping to a table structure like following:

Id int primary key Name varchar 50 Banner varchar 50 Homeaddress varchar 250 Emailaddress varchar 250

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