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Build a Better Python Web APP
| Date post: | 28-Jan-2018 |
| Category: |
Technology |
| Upload: | developers-connect-devcon-philippines |
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Build a
Better
Python Web APP
MongoDB
• Much faster than SQL databases
• No need to learn query languages* and setups
• Easier to scale when designed properly
Install pymongo
pip install pymongo
easy_install pymongo
Hello World
from pymongo import MongoClient
client = MongoClient("localhost", 27017)
db = client.databasename
Step
from pymongo import MongoClient
Import MongoClient from pymongo
client = MongoClient("localhost", 27017)
Connect to the mongodb server at the IP address and port defined
db = client.databasename
Access a specific database in the mongodb server
collection = db.collectionname
Access a specific collection (table in SQL) in the selected db
Basic DB Operations
•Create
•Read
•Update
•Delete
Create@route("/register", method="POST")
def newuser():
username = request.forms.get("username")
password = request.forms.get("password")
email = request.forms.get("email")
userdata = {"name":username, "password":password, "email":email}
try:
db.users.save(userdata)
except:
return {"status":"ERROR"}
return {"status":"OK"}
Step
username = request.forms.get("username")
Get the username, password, email to data from the forms
userdata = {"name":username, "password":password,
"email":email}
Create a dictionary with the data obtained above
try:
Setup an exception handler
Step
db.users.save(userdata)
Save the dictionary to the users collection in the db we connected before
except:
Start of the exception block. This will execute when the db save fails
Read@route("/user/list")
def listuser():
usercursor = db.users.find({},{"_id":False})
users = list(usercursor)
return {"users":users}
Step
usercursor = db.users.find({},{"_id":False})
Find all entries in the collection named users and do not show the _id field
users = list(usercursor)
Convert the cursor object into a list, which we can be converted to a json object
return {"users":users}
Return the list of users to the browser
The Query Formatdb.collectionname.find(filter,projection)
Filter is the expression that needs to be true an element to be includedExamples:• {} = will return all• {“name”:”paolo”} = will only return entries with name exactly to “paolo”• {“name”:”paolo”, “age”:{“$lte”:30}} = will only return entries with names exactly “paolo” and age
is less than or equal to 30See more filter operators here: https://docs.mongodb.com/manual/reference/operator/query/
The Query Formatdb.collectionname.find(filter,projection)
Projection controls what fields will be shown, done by setting field names True or FalseExamples:{“name”:True}{“_id”:False}
Inputs in BottleVia POST body
@route('/login', method="POST")
def login():
username = request.forms.get("username")
password = request.forms.get("password")
acceptedpasswords = ["gloopgroup", "devconph" ,
"adventuretime"]
if password in acceptedpasswords:
return "Welcome "+ username
else:
return "Unauthorized"
Visit: localhost:8001/login using login page
Activity 1
Create a calculator api:http://localhost:8001/operation/operand1/operand2
will return the value of
operand1 <operation> operand2
Example:
/subtraction/10/2 will output 8
Common Return TYPESPlain Text
Similar to what we were doing earlier
Common Return TYPESBinary
When returning files like images, video, audio, pdfs…
Common Return TYPESJSON
The common return type for APIs
Example: FB API
/{userid}/friends
{
"data": [
{
"name": "Terence Pua",
"id": "608407"
},
{
"name": "Gene Paul Quevedo",
"id": "10153785024974240"
},
{
"name": "Jc Velasquez",
"id": "722462218"
},
{
"name": "Jomel C. Imperio",
"id": "779287017"
}
],
"summary": {
"total_count": 770
}
}
Common Return TYPESHTML
Return web pages with dynamic/static content<!DOCTYPE html><html itemscope itemtype="http://schema.org/QAPage"><head>
<title>regex - Validate email address in JavaScript? - Stack Overflow</title><link rel="shortcut icon" href="//cdn.sstatic.net/Sites/stackoverflow/img/favicon.ico?v=4f32ecc8f43d"><link rel="apple-touch-icon image_src" href="//cdn.sstatic.net/Sites/stackoverflow/img/apple-touch-icon.png?v=c78bd457575a"><link rel="search" type="application/opensearchdescription+xml" title="Stack Overflow" href="/opensearch.xml"><meta name="twitter:card" content="summary"><meta name="twitter:domain" content="stackoverflow.com"/><meta property="og:type" content="website" />
<meta property="og:image" itemprop="image primaryImageOfPage" content="http://cdn.sstatic.net/Sites/stackoverflow/img/[email protected]?v=73d79a89bded&a" />
<meta name="twitter:title" property="og:title" itemprop="title name" content="Validate email address in JavaScript?" /><meta name="twitter:description" property="og:description" itemprop="description" content="How can an email address be validated
in JavaScript?" /><meta property="og:url" content="http://stackoverflow.com/questions/46155/validate-email-address-in-javascript"/><link rel="canonical" href="http://stackoverflow.com/questions/46155/validate-email-address-in-javascript" />
Returning JSON ObjectJSON
Simply return a dictionary or list
@route("/json")
def jason():
return {"lastname":"bourne", "alias":"David Webb"}
Returning Static HTMLHTML
Use static_file from bottle
@route("/loginpage")
def loginpage():
return static_file("login.html", root=".")
Testing the POST Handler
Visit localhost:8081/loginpage
Type your name and use any of these as passwordg
gloopgroup, devconph, adventuretime
Click submit
The POST Request Cycle<form action="/login" method="POST">
Method dictates what kind of request happens when submittedAction tells the browser where to submit the request
<input type="text" name="username">
Adds a text input that will be associated to the username field
<input type="password" name="password">
Adds a password input that will be associated to the password field
<input type="submit">
Adds a button that submits the form when clicked
Returning Dynamic HTMLHTML
Use a templating engine:
• Library that can substitute variables into a template quickly and cleanly
• Isolates the designer’s job of designing and the coder’s job of coding
Install Tenjin
pip install tenjin
easy_install tenjin
Using Tenjinfrom gevent import monkey;
monkey.patch_all()
from bottle import run, route, request
import tenjin
from tenjin.helpers import *
@route("/introduction/<name>/<age>/<work>")
def template1(name, age, work):
context = {"name":name, "age":age, "work":work}
return engine.render("introduction.html", context);
engine = tenjin.Engine(path=['.'])
run(server='gevent', host="localhost", port=8001, debug=True)
The template<!doctype html>
<html lang="en">
<head>
<title>Login</title>
</head>
<body>
<h1>${name}</h1>
<h2>Age:${age}<h2>
<h2>Work:${work}<h2>
</body>
</html>
Stepfrom gevent import monkey;
monkey.patch_all()
from bottle import run, route, request
import tenjin
from tenjin.helpers import *
Import all libraries, including tenjin and all helper methods
@route("/introduction/<name>/<age>/<work>")
Define a route for the url, and define variables in it
def template1(name, age, work):
Declare a request handler and receive the variables from the url
Stepcontext = {"name":name, "age":age, "work":work}
Define a context variable, which is a dictionary of values that will be substituted into the template
return engine.render("introduction.html", context);
Render the template called introduction.html using the context variable named context, and return it to the browser
engine = tenjin.Engine(path=['.'])
Instructs the templating engine to look for the templates in the directories listed in path
Step (Inside the template)
<!doctype html>
<html lang="en">
<head>
<title>Login</title>
</head>
<body>
<h1>${name}</h1>
<h2>Age:${age}<h2>
<h2>Work:${work}<h2>
</body>
</html>
{
"name":"Paolo",
"age":"30",
"work":"Synergist"
}
+
Displaying Lists
@route("/spell/<word>")
def template1(word):
letters = list(word)
context = {"letters":letters, "word":word}
return engine.render("speller.html", context);
Step@route("/spell/<word>")
Define a route that accepts a variable assigned to word
def speller(word):
Define a handler that accepts a variable named word
letters = list(word)
Convert the text string into a list object. From a string “word”, it becomes a list [“w”, “o”, “r”, “d”]
Stepcontext = {"letters":letters}
Define a context variable, which contains the list of letters we just created
return engine.render("speller.html", context);
Render the template called speller.html using the context variable named context, and return it to the browser
Step (Inside the template)
<?py for letter in letters: ?>
Loop on the elements of the list named letters
<h3>${letter}</h3><br>
Display the element letter along with the html
<?py #endfor ?>
Denote where the loop ends in the template
<a href="/greet/${word}">greet ${word}</a>Create a link that will call the greet API we created earlier
{"letters":["s", "u", "s", "h", "i"]}
Highlighting Names
@route("/profiles/<name>")
def profile(name):
users = [
{"name":"Em", "image":"http://goo.gl/aDxeu1", "age":30,
"work":"Futurist"},
{"name":"Paolo", "image":"http://goo.gl/5k2oZr", "age":30,
"work":"Synergist"}
]
context = {"users":users, "name":name}
return engine.render("profiles.html", context)
Stepusers = [
{"name":"Em", "image":"http://goo.gl/aDxeu1", "age":30, "work":"Futurist"},
{"name":"Paolo", "image":"http://goo.gl/5k2oZr", "age":30, "work":"Synergist"}
]
Define a list of dictionaries, with each dictionary object containing information about a user. It contains information name, url of the image, age, and work
context = {"users":users, "name":name}
Define a conext containing the name to be highlighted, and the list of users
return engine.render("profiles.html", context)
Render the template named profiles.html with the context
Step (Inside the template)
<?py for user in users: ?>
Loop on the elements of the list named users, each element in the list can be referred to using the user variable
<div style="height:100px;">
Create a div element in the html to contain one user element
<img src="${user['image']}" style="float:left;
height:100%;"/>
Place an image in the html coming from the url defined in user[‘image’]
Step (Inside the template)
<?py if name==user["name"]: ?>
Compare the current user’s name to the name entered in the url
<strong>Name: ${user['name']}</strong>
This happens when the above condition is true, display the name as bold characters
<?py else: ?>
Add an else handler that executes if condition is not met
Step (Inside the template)
Name: ${user['name']}
This happens when primary condition is not met, display the user’s name without any decorations
<?py #endif ?>
Denote where the if statement ends
Make a Sushi Menu
Create a menu using all the sushi items in the sushilist variable
Display the image and name of the sushi
When the menu item is clicked, it should display another page containing the name, image, price, and rating of the sushi (defined in the sushilist variable)
The most creative presentation of the menu wins a prize
Activity 1
pip install gevent
pip install bottle
Cost per Mille =• Cost per 1000 impressions
• Abuse of statistics
• i.e. Magic
• i.e. It sucks
• Not based on empirical measured data
ADVERTISING!
Eyeballs
cost
How many are watching me right now?How many are paying attention?How many are interested?How many are still reading this part?How about now?Now?
ROUTER ON
PROMISCUOUS MODE
DEVICEs SENDING
PROBE REQUESTS
PYTHON
+TCPDUMPWe get this
Pilot Installation
23000Passers-by
39%viewed
10%Finished
Meh…
Map movement
Geofencing alternative
Detection
perimeter
snoop
turn off your phones
when going to the lagoon
