python : Flask Basic

Flask (Python WebFramework )

Pre Req :

1. make sure python is installed in your system

2. pip install flask in terminal or cmd line.(python package installer)

Note:

1.         Default method =GET (if not mentioned)

2.         Use ARC , Postman etc., to make post statements

3.         “submit” button in html triggers post.

Use host="0.0.0.0" and port forward when using with docker

Example #app.run(host='0.0.0.0', port="5432",debug=True)

https://medium.com/@umerfarooq_26378/web-services-in-python-ef81a9067aaf

Html Template :

from flask import request,Flask,json,render_template

app = Flask(__name__)

@app.route(“/resource”)

Def xxx(resource)

                        ….

                        …..

if __name__ == "__main__":

    app.run(host='0.0.0.0', port=1234 , Debug=true)

Passing Args

#http://localhost:1234/hello?name=Luis

@app.route('/hello')

def api_hello():

    if 'name' in request.args:

        return 'data: ' + request.args['name']

    else:

        return 'Data: no data'

Any Resource

'''http://localhost:1234/any_string

@app.route("/<string:name>/")

def string_var(name):

    return "string_variable: "+name

Any Resource displaying html

#http://localhost:1234/random_string

#make sure “templates” folder is created insede project with image.html

@app.route("/<string:name>/") #<int:value>

def hello(name):

    return render_template('image2.html', name=name)

All Methods

''' GET/POST/PATCH/PUT/DELETE

   http://localhost:1234/verb ‘’’

@app.route('/verb', methods = ['GET', 'POST', 'PATCH', 'PUT', 'DELETE'])

def api_echo():

    if request.method == 'GET':

        return "verb: GET\n"

    elif request.method == 'POST':

        return "verb: POST\n"

    elif request.method == 'PATCH':

        return "verb: PACTH\n"

    elif request.method == 'PUT':

        return "verb: PUT\n"

    elif request.method == 'DELETE':

        return "verb: DELETE"

POST with body in REST

'''example

POST   http://localhost:1234/messages

H "Content-type: application/json"

-body '{"message":"Hello Data"}'

'''

@app.route('/messages', methods = ['POST'])

def api_message():

    if request.headers['Content-Type'] == 'text/plain':

        return "Text Message: " + str(request.data)

    elif request.headers['Content-Type'] == 'application/json':

        return "JSON Message: " + json.dumps(request.json)

    else:

        return "returns raw data:"+request.get_data()

POST accept from Html and send to html

Note:

1.         submit button in html to trigger POST

2.         Save html code in Project/templates/name.html

3.         Use Javascript inside html to manipulate data.

4.         Data is received to flask as dictionary

5.         Python data accessed in html as “{{}}”

6.         “url_for” used instead of “http://localhost:8003/submit”

input_data.html

<form action="{{ url_for('submit') }}" method="post">

    <textarea name="text"></textarea>

 <textarea name="text2"></textarea>

    <input type="submit">

</form>

output_2data.html

<p>text1&nbsp;<input name="text1" type="text" value={{text1}}/></p>

<p>text2&nbsp;<input name="text2" type="text" value={{text2}}/></p>

input_data2.py

from flask import Flask, request, render_template

app = Flask(__name__)

@app.route('/')

def index():

    return render_template('input_data.html')

@app.route('/submit', methods=['POST'])

def submit():

    data=request.form

    data1=data['text']

    data2=data['text2']

    return render_template("output_2data.html",text1=data1,text2=data2)

    #return 'You entered: {}'.format(request.form['text'])

if __name__ == "__main__":

    app.run(host='0.0.0.0', port=8003)

 Error handle

@app.errorhandler(404)

def not_found(error=None):

    message = {  'status': 404,  'message': 'Not Found: ' + request.url}

    resp = jsonify(message)

    resp.status_code = 404

    return resp