keyword arguments
Keyword arguments (or named arguments) are values that, when passed into a function, are identifiable by specific parameter names.
A keyword argument is preceded by a parameter and the assignment operator, = . Keyword arguments can be likened to dictionaries in that they map a value to a keyword.
The order of the arguments does not matter
def my_function(child3, child2, child1):
print("The youngest child is " + child3)
my_function(child1 = "Emil", child2 = "Tobias", child3 = "Linus")The phrase Keyword Arguments are often shortened to kwargs in Python documentations.
arguments vs keyword arguments (*args vs **kwargs)
def foo(*args, **kwargs):
print(args);
print(kwargs);
foo(5, 6, 7, name="Shailesh", age=32, city="Nagpur");
Decorators
A decorator is a design pattern in Python that allows a user to add new functionality to an existing object without modifying its structure.
Decorators are usually called before the definition of a function you want to decorate.
### CREATE CUSTOM DECORATOR ###
from functools import wraps
def my_decorator(f):
@wraps(f)
def msg(*args, **kwargs):
print("I am from custom decorator")
print("Arguments:", args)
print("Keyword Arguments:", kwargs)
return f(*args, **kwargs)
return msg;
@my_decorator
def add(x, y):
print(f"{x} + {y} = {x + y}")
@my_decorator
def sub(x, y):
print(f"{x} - {y} = {abs(x - y)}")
#invoke functions
add(5, y=6)
sub(5, y=6)
Flask Framework
Flask is a micro web framework written in Python. It is classified as a microframework because it does not require particular tools or libraries.
It has no database abstraction layer, form validation, or any other components where pre-existing third-party libraries provide common functions.
install flask module
python -m pip install Flaskhello world
from flask import Flask, jsonify, request, render_template
app = Flask(__name__)
#YOUR FUNCTIONS HERE
if __name__ == "__main__":
app.run(debug=True);
#app.run(host="0.0.0.0", port=int("1234"), debug=True)render html template [NOTE: MAKE SURE TO KEEP ALL TEMPLATE FILES IN templates DIRECTORY]
@app.route('/')
def index():
#return "Hello World";
data = {'company_name': "TCET"}
return render_template('hello_world.html', data = data)templates/hello_world.html
<h1>Hello World</h1>
<h3>Welcome to {{data['company_name']}}</h3>read get value
@app.route('/sqr', methods=['GET'])
def getSqr():
num1 = int(request.args.get('num1'));
return f"Square of {num1} is {num1 * num1}"
@app.route('/add', methods=['GET'])
def add():
num1 = int(request.args.get('num1'));
num2 = int(request.args.get('num2'));
return f"{num1} + {num2} = {num1 + num2}";read post value
@app.route('/sub', methods=['POST'])
def sub():
num1 = int(request.form.get('num1'));
num2 = int(request.form.get('num2'));
return f"{num1} - {num2} = {num1 - num2}";read raw json
@app.route('/mul', methods=['POST'])
def mul():
raw_json = request.get_json();
num1 = int(raw_json['num1']);
num2 = int(raw_json['num2']);
return f"{num1} * {num2} = {num1 * num2}";install pymysql module
python -m pip install PyMySQLinstall cors module
python -m pip install -U flask-corsget users from database
from flask import Flask, jsonify, request
from flask_cors import CORS
import pymysql
app = Flask(__name__)
cors = CORS(app)
@app.route('/users', methods=['GET'])
def get_users():
# To connect MySQL database
conn = pymysql.connect(host='localhost', user='root', password = "", db='databasename')
cur = conn.cursor()
cur.execute("select * from users LIMIT 10")
output = cur.fetchall()
print(type(output)); #this will print tuple
for rec in output:
print(rec);
# To close the connection
conn.close()
return jsonify(output);fetch data using javascript fetch api
let url = "http://localhost:5000";
fetch(url)
.then(response => response.json())
.then(response => console.table(response));Flask RESTful API
Flask-RESTful is an extension for Flask that adds support for quickly building REST APIs.
install flask-restful
python -m pip install flask-restfulMyApi Resource
from flask import Flask, request
from flask_restful import Resource, Api
app = Flask(__name__)
api = Api(app)
class MyApi(Resource):
def __init__(self):
print("Constructor called...")
def get(self):
return {"msg" : "get method"}
def post(self):
return {"msg" : "post method"}
def put(self):
return {"msg" : "put method"}
def delete(self):
return {"msg" : "delete method"}
api.add_resource(MyApi, '/myapiurl')
if __name__ == "__main__":
app.run(debug=True)Authenticate REST API
from flask import Flask, request, make_response
from flask_restful import Resource, Api
from functools import wraps
app = Flask(__name__)
api = Api(app)
#define custom decorator @authorize
def authorize(f):
@wraps(f)
def kuchbhi(*args, **kwargs):
err_msg = "Authentication required";
if(request.authorization == None):
return make_response('Not Authorized', 403, {'WWW-Authenticate' : err_msg})
unm = request.authorization.username
pwd = request.authorization.password
if(unm == 'admin' and pwd == 'admin@123'):
print("Correct username and password")
return f(*args, **kwargs)
return make_response('Not Authorized', 403, {'WWW-Authenticate' : err_msg})
return kuchbhi
class MyApi(Resource):
def __init__(self):
print("Constructor called...")
@authorize
def get(self):
return {"msg" : "get method"}
@authorize
def post(self):
return {"msg" : "post method"}
@authorize
def put(self):
return {"msg" : "put method"}
@authorize
def delete(self):
return {"msg" : "delete method"}
api.add_resource(MyApi, '/myapiurl')
if __name__ == "__main__":
app.run(debug=True)
apply authorize decorator to all methods of call
from flask import Flask, request, make_response
from flask_restful import Resource, Api
from functools import wraps
app = Flask(__name__)
api = Api(app)
#define custom decorator authorize
def authorize(f):
@wraps(f)
def kuchbhi(*args, **kwargs):
err_msg = "Authentication required";
if(request.authorization == None):
return make_response('Not Authorized', 403, {'WWW-Authenticate' : err_msg})
unm = request.authorization.username
pwd = request.authorization.password
if(unm == 'admin' and pwd == 'admin@123'):
print("Correct username and password")
return f(*args, **kwargs)
return make_response('Not Authorized', 403, {'WWW-Authenticate' : err_msg})
return kuchbhi
class MyApi(Resource):
method_decorators = [authorize]
def __init__(self):
print("Constructor called...")
def get(self):
return {"msg" : "get method"}
def post(self):
return {"msg" : "post method"}
def put(self):
return {"msg" : "put method"}
def delete(self):
return {"msg" : "delete method"}
api.add_resource(MyApi, '/myapiurl')
if __name__ == "__main__":
app.run(debug=True)Testing API
test response status
test_myapiapp.py
where myapiapp.py is the file where all restful api defined
#from filename import app
from rest_api import app
import unittest
import base64
class RestAPITest(unittest.TestCase):
def test_status(self):
tester = app.test_client(self)
response = tester.get('/myapiurl')
self.assertEqual(response.status_code, 200)
if __name__ == "__main__":
unittest.main()test content type
def test_content_type(self):
tester = app.test_client(self)
response = tester.get('/myapiurl')
self.assertEqual(response.content_type, "application/json")test content data
def test_content(self):
tester = app.test_client(self)
response = tester.get('/myapiurl')
self.assertTrue(b'get' in response.data)To pass Basic Auth credentials in header
creds = base64.b64encode(b"admin:admin@123").decode("utf-8")
response = tester.get('/myapiurl', headers={"Authorization": f"Basic {creds}"})complete test file code
#from filename import app
from rest_api import app
import unittest
import base64
class RestAPITest(unittest.TestCase):
def test_status(self):
tester = app.test_client(self)
#response = tester.get('/myapiurl')
creds = base64.b64encode(b"admin:admin@123").decode("utf-8")
response = tester.get('/myapiurl', headers={"Authorization": f"Basic {creds}"})
self.assertEqual(response.status_code, 200)
def test_content_type(self):
tester = app.test_client(self)
#response = tester.get('/myapiurl')
creds = base64.b64encode(b"admin:admin@123").decode("utf-8")
response = tester.get('/myapiurl', headers={"Authorization": f"Basic {creds}"})
self.assertEqual(response.content_type, "application/json")
def test_content(self):
tester = app.test_client(self)
#response = tester.get('/myapiurl')
creds = base64.b64encode(b"admin:admin@123").decode("utf-8")
response = tester.get('/myapiurl', headers={"Authorization": f"Basic {creds}"})
self.assertTrue(b'get' in response.data)
if __name__ == "__main__":
unittest.main()
REST API CRUD
app.py
import pymysql
from flask import Flask, jsonify, request
from flask_cors import CORS
import pymysql
app = Flask(__name__)
cors = CORS(app)
# To connect MySQL database
conn = pymysql.connect(host='yourhost', user='youruser', password = "yourpassword", db='yourdatabase')
@app.route('/users', methods=['GET'])
def get_users():
cur = conn.cursor(pymysql.cursors.DictCursor)
cur.execute("select * from users LIMIT 10")
output = cur.fetchall()
print(type(output)); #this will print tuple
for rec in output:
print(rec);
# To close the connection
#conn.close()
return jsonify(output);
@app.route('/users/get_one_record', methods=['GET'])
def get_single_user():
cur = conn.cursor(pymysql.cursors.DictCursor)
userid = int(request.args.get('id'));
cur.execute(f"select * from users WHERE id = {userid}")
output = cur.fetchone()
return jsonify(output);
@app.route('/users', methods=['DELETE'])
def deleteRecord():
cur = conn.cursor()
id = int(request.args.get('id'));
query = f"delete from users where id = {id}";
#print(query)
res = cur.execute(query);
conn.commit();
print(cur.rowcount, "record(s) deleted")
return "Record deleted sussesfully"
@app.route('/users', methods=['POST'])
def insertRecord():
#get raw json values
raw_json = request.get_json();
name= raw_json['name'];
age= raw_json['age'];
city= raw_json['city'];
sql="INSERT INTO users (id,name,age,city) VALUES (NULL,'"+name+"','"+str(age)+"','"+city+"')";
cur= conn.cursor()
cur.execute(sql);
conn.commit()
return "Record inserted Succesfully"
@app.route('/users', methods=['PUT'])
def updateRecord():
raw_json = request.get_json();
#print(type(raw_json));
id = raw_json['id'];
name= raw_json['name'];
age= raw_json['age'];
city= raw_json['city'];
sql_update_quary=("UPDATE users SET name = '"+name+"',age = '"+str(age)+"',city = '"+city+"'WHERE id = '"+str(id)+"'");
cur= conn.cursor()
cur.execute(sql_update_quary);
conn.commit()
return "Record Updated Sussecfully";
if __name__ == "__main__":
#app.run(debug=True);
app.run(host="0.0.0.0", port=int("1235"), debug=True)
script.js
//const api_url = "<heroku_app_url>"
const api_url = "http://localhost:8080/users"
function loadData(records = []) {
var table_data = "";
for(let i=0; i<records.length; i++) {
table_data += `<tr>`;
table_data += `<td>${records[i].name}</td>`;
table_data += `<td>${records[i].age}</td>`;
table_data += `<td>${records[i].city}</td>`;
table_data += `<td>`;
table_data += `<a href="edit.html?id=${records[i].id}"><button class="btn btn-primary">Edit</button></a>`;
table_data += ' ';
table_data += `<button class="btn btn-danger" onclick=deleteData('${records[i].id}')>Delete</button>`;
table_data += `</td>`;
table_data += `</tr>`;
}
//console.log(table_data);
document.getElementById("tbody").innerHTML = table_data;
}
function getData() {
fetch(api_url)
.then((response) => response.json())
.then((data) => {
console.table(data);
loadData(data);
});
}
function getDataById(id) {
fetch(`${api_url}/get_one_record?id=${id}`)
.then((response) => response.json())
.then((data) => {
console.log(data);
document.getElementById("id").value = data.id;
document.getElementById("name").value = data.name;
document.getElementById("age").value = data.age;
document.getElementById("city").value = data.city;
})
}
function postData() {
var name = document.getElementById("name").value;
var age = document.getElementById("age").value;
var city = document.getElementById("city").value;
data = {name: name, age: age, city: city};
fetch(api_url, {
method: "POST",
headers: {
'Accept': 'application/json',
'Content-Type': 'application/json'
},
body: JSON.stringify(data)
})
.then((response) => response.json())
.then((data) => {
console.log(data);
window.location.href = "index.html";
})
}
function putData() {
var id = document.getElementById("id").value;
var name = document.getElementById("name").value;
var age = document.getElementById("age").value;
var city = document.getElementById("city").value;
data = {id: id, name: name, age: age, city: city};
fetch(api_url, {
method: "PUT",
headers: {
'Accept': 'application/json',
'Content-Type': 'application/json'
},
body: JSON.stringify(data)
})
.then((response) => response.json())
.then((data) => {
console.table(data);
window.location.href = "index.html";
})
}
function deleteData(id) {
user_input = confirm("Are you sure you want to delete this record?");
if(user_input) {
//url = "http://localhost:8080/users?id=1234"
fetch(`${api_url}?id=${id}`, {
method: "DELETE",
headers: {
'Accept': 'application/json',
'Content-Type': 'application/json'
},
body: JSON.stringify({"_id": id})
})
.then((response) => response.json())
.then((data) => {
console.log(data);
window.location.reload();
})
}
}index.html
<!DOCTYPE html>
<html>
<head>
<title>CIA Institute - Python Flask Project</title>
<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/css/bootstrap.min.css" rel="stylesheet" crossorigin="anonymous">
<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/js/bootstrap.bundle.min.js"crossorigin="anonymous"></script>
</head>
<body class="d-flex flex-column h-100 container">
<header>
<nav class="navbar navbar-expand-lg navbar-expand-sm navbar-light bg-light">
<div class="container-fluid">
<div class="collapse navbar-collapse" id="navbarNavAltMarkup">
<div class="navbar-nav">
<a class="nav-link active" aria-current="page" href="#">Listing</a>
<a class="nav-link" href="add.html">Add New</a>
</div>
</div>
</div>
</nav>
</header>
<table class="table table-striped table-hover text-center">
<thead>
<th>Name</th>
<th>Age</th>
<th>City</th>
<th>Action</th>
</thead>
<tbody id="tbody">
</tbody>
<tfoot>
</tfoot>
</table>
<footer class="footer mt-auto py-3 bg-light">
<div class="container text-center">
<span class="text-muted"> © CIA Institute 2023</span>
</div>
</footer>
</body>
<script src="script.js"></script>
<script>
getData();
</script>
</html>
add.html
<html>
<head>
<title>CIA Institute - Python Flask Project</title>
<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/css/bootstrap.min.css" rel="stylesheet" crossorigin="anonymous">
<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/js/bootstrap.bundle.min.js"crossorigin="anonymous"></script>
</head>
<body class="d-flex flex-column h-100 container">
<header>
<nav class="navbar navbar-expand-lg navbar-expand-sm navbar-light bg-light">
<div class="container-fluid">
<div class="collapse navbar-collapse" id="navbarNavAltMarkup">
<div class="navbar-nav">
<a class="nav-link" href="index.html">Listing</a>
<a class="nav-link active" aria-current="page" href="add.html">Add New</a>
</div>
</div>
</div>
</nav>
</header>
<h3>Add Document</h3>
<form onsubmit="return false;">
<div class="mb-3">
<label for="name" class="form-label">Name</label>
<input type="text" class="form-control" id="name" autofocus>
</div>
<div class="mb-3">
<label for="exampleInputPassword1" class="form-label">Age</label>
<input type="text" class="form-control" id="age">
</div>
<div class="mb-3">
<label for="city" class="form-label">City</label>
<input type="text" class="form-control" id="city">
</div>
<button class="btn btn-primary" onclick="return postData()">Submit</button>
<a href="index.html" class="btn btn-primary">Cancel</a>
</form>
<footer class="footer mt-auto py-3 bg-light">
<div class="container text-center">
<span class="text-muted"> © CIA Institute 2022</span>
</div>
</footer>
</body>
<script src="script.js"></script>
<script>
</script>
</html>
edit.html
<html>
<head>
<title>CIA Institute - Python Flask Project</title>
<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/css/bootstrap.min.css" rel="stylesheet" crossorigin="anonymous">
<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/js/bootstrap.bundle.min.js"crossorigin="anonymous"></script>
</head>
<body class="d-flex flex-column h-100 container">
<header>
<nav class="navbar navbar-expand-lg navbar-expand-sm navbar-light bg-light">
<div class="container-fluid">
<div class="collapse navbar-collapse" id="navbarNavAltMarkup">
<div class="navbar-nav">
<a class="nav-link" href="index.html">Listing</a>
<a class="nav-link active" aria-current="page" href="add.html">Add New</a>
</div>
</div>
</div>
</nav>
</header>
<h3>Edit Document</h3>
<form onsubmit="return false;">
<input type="hidden" class="form-control" id="id">
<div class="mb-3">
<label for="name" class="form-label">Name</label>
<input type="text" class="form-control" id="name" autofocus>
</div>
<div class="mb-3">
<label for="exampleInputPassword1" class="form-label">Age</label>
<input type="text" class="form-control" id="age">
</div>
<div class="mb-3">
<label for="city" class="form-label">City</label>
<input type="text" class="form-control" id="city">
</div>
<button class="btn btn-primary" onclick="return putData()">Update</button>
<a href="index.html" class="btn btn-primary">Cancel</a>
</form>
<footer class="footer mt-auto py-3 bg-light">
<div class="container text-center">
<span class="text-muted"> © CIA Institute 2022</span>
</div>
</footer>
</body>
<script src="script.js"></script>
<script>
const urlParams = new URLSearchParams(window.location.search);
const id = urlParams.get('id');
getDataById(id);
</script>
</html>
