have you ever used gmail or hotmail on the web? it seems so natural that we take it for granted. in this post we’ll see how to build a basic web mail client to send mail … using flask and pi as server. this is
content
flask intro : folder structure
flask intro : requests
flask : basic app
flask : post
flask intro : folder structure
flask is a python web framework, it is recommended to learn it before django. a typical flask project structure is as follows:
let us say we name our project sendmail, the project structure is
sendmail [folder]
|_ _ app.py
|_ _ templates [folder]
| |_ _ file.html
|_ _ static [folder]
|_ _ style.css
to run a flask app you don’t need the templates and static folder but they are here for good reasons
the templates folder
let us say you have a website and for each page there are some elements recurring like the header and footer. having a template allows you to specify only the changing data
templating engine
flask uses the jinja templating engine for rendering variables etc
{{name}} will display the variable name on rendering. more on that later
static folder
static means it won’t change, load your non-changing assets in there
flask intro : requests
for a webserver, whatever you type in the address bar after specifying the correct ip is a request
http://www.domain.com/water.html
requests the file water.html
in flask however (and python), you need not request for only files, you can pretty much mould the request pattern
http://www.domain.com/mult/5/by/2 http://www.domain.com/show/user54/sea
flask : basic app
a basic app in flask is as follows :
from flask import Flask
app = Flask(__name__)
@app.route('/')
def basic():
return 'welcome to my site'
if __name__ == '__main__': # if file run
app.run(debug=True, host='0.0.0.0')
explanations
@app.route('/')
means the first slash after the domain name if requested
you define the action in the subsequent function, which can be named as you want
let us say the domain is www.d.com, we are specifying what to do when www.d.com/ is requested
return 'welcome to my site'
displays a single string
app.run(debug=True, host='0.0.0.0')
host=’0.0.0.0′ runs the app on 192.168. …
flask : basic app : return page
from flask import Flask, render_tempplate
app = Flask(__name__)
@app.route('/')
def basic():
return render_template('index.html')
if __name__ == '__main__':
app.run(debug=True, host='0.0.0.0')
here
return render_template('index.html')
returns the file index.html in the templates folder
flask : post
there are two request methods viz post and get, post is more secure than get
here is a post demo :
our html
<form method="POST"> <input type="text" name="xyz"> <br> <input type="submit" value="Send"> </form>
our post handling method:
@app.route('/', methods=['GET', 'POST'])
def index():
if request.method == 'POST': #this block is only entered when the form is submitted
data = request.form['xyz']
return 'data entered :{}'.format(data)
return render_template('index.html')
our app
here is the code for our index.html file in our templates folder :
<!DOCTYPE html> <html> <head> <title></title> <meta name="viewport" content="width=device-width, initial-scale=1.0"> </head> <body> <form method="POST"> to:<br> <input type="text" name="to"> <br> subject:<br> <input type="text" name="subject"> <br> body:<br> <textarea rows="4" cols="50" type="text" name="body"> </textarea> <br><br> <input type="submit" value="Send"> </form> </body> </html>
our app.py code :
from flask import Flask, render_template, request
# send mail function
import smtplib
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from email.header import Header
def send_mail(to_, subject_, body_):
fromaddr='[address]'
toaddr=to_
thesub=subject_
thebody=body_
thepassword='[pass]'
domsmtp='smtp.gmail.com'
smtpport= 587 #needs integer not string
msg = MIMEMultipart('alt text here')
msg.set_charset('utf8')
msg['From'] = fromaddr
msg['To'] = toaddr
msg['Subject'] = Header(thesub,'utf8')
_attach = MIMEText(thebody.encode('utf8'),'html','UTF-8')
msg.attach(_attach)
server = smtplib.SMTP(domsmtp, smtpport)
server.starttls()
server.login(fromaddr, thepassword)
text = msg.as_string()
server.sendmail(fromaddr, toaddr, text)
server.quit()
print('mail sent')
app = Flask(__name__)
@app.route('/', methods=['GET', 'POST'])
def index():
if request.method == 'POST': #this block is only entered when the form is submitted
to = request.form['to']
subject = request.form['subject']
body = request.form['body']
send_mail(to, subject, body)
return 'mail sent to {}'.format(to)
return render_template('index.html')
if __name__ == '__main__':
app.run(debug=True, host='0.0.0.0')
just replace [address] and [pass] by your actual data
now run app.py, and see the output
you can grab another device on the network, go to 192.168. … depending, and … you can send a mail from another device, from a web interface