Author: John Au-Yeung

Sometimes, we want to percent-encode URL parameters in Python.

In this article, we’ll look at how to percent-encode URL parameters in Python.

How to percent-encode URL parameters in Python?

To percent-encode URL parameters in Python, we can use the urllib.parse.quote method.

For instance, we write:

import urllib.parse

query = urllib.parse.quote("Müller".encode('utf8'))
print(query)
print(urllib.parse.unquote(query))

We call urllib.parse.quote to percent encode the "Müller" string.

We’ve to call encode to encode it as a utf-8 binary string before we do the percent encoding.

Then we call urllib.parse.unquote to percent decode the string back to the original string.

Therefore, we see:

M%C3%BCller
Müller

printed.

Conclusion

To percent-encode URL parameters in Python, we can use the urllib.parse.quote method.

Sometimes, we want to avoid exceeding max retries with URL in requests with Python.

In this article, we’ll look at how to avoid exceeding max retries with URL in requests with Python.

How to avoid exceeding max retries with URL in requests with Python?

To avoid exceeding max retries with URL in requests with Python, we can make our requests with the requests module.

For instance, we write:

import requests
from requests.adapters import HTTPAdapter
from requests.packages.urllib3.util.retry import Retry

url = 'http://example.com'
session = requests.Session()
retry = Retry(connect=3, backoff_factor=0.5)
adapter = HTTPAdapter(max_retries=retry)
session.mount('http://', adapter)
session.mount('https://', adapter)

session.get(url)

We use the Retry class to set the max number of retries.

total is the total retries to allow.

backoff_factor is the factor to apply between attempts.

Then we can use the returned object as the value of max_retries parameter of the HTTPAdapter constructor.

And we use the adapter for the requests with http and https requests by calling session.mount.

Finally, we make our GET request with session.get.

Conclusion

To avoid exceeding max retries with URL in requests with Python, we can make our requests with the requests module.

Sometimes, we want to choose longest string in list with Python.

In this article, we’ll look at how to choose longest string in list with Python.

How to choose longest string in list with Python?

To choose longest string in list with Python, we can use the max function with the key parameter set to len.

For instance, we write:

l = ['123', '123456', '1234']
m = max(l, key=len)
print(m)

We call max on list l with key set to len compare each entry in l by their lengths.

Therefore, the longest string will be returned.

And m is '123456'.

Conclusion

To choose longest string in list with Python, we can use the max function with the key parameter set to len.

Sometimes, we want to send email to multiple recipients using Python smtplib.

In this article, we’ll look at how to send email to multiple recipients using Python smtplib.

How to send email to multiple recipients using Python smtplib?

To send email to multiple recipients using Python smtplib, we can use the sendmail method.

For instance, we write:

import smtplib
from email.mime.text import MIMEText

s = smtplib.SMTP('smtp.live.com')
s.set_debuglevel(1)
msg = MIMEText("""body""")
sender = 'me@example.com'
recipients = ['john.doe@example.com', 'john.smith@example.co.uk']
msg['Subject'] = "subject line"
msg['From'] = sender
msg['To'] = ", ".join(recipients)
s.sendmail(sender, recipients, msg.as_string())

We create the SMTP instance by using the SMTP server address as the argument.

Then we create the message with the MIMEText class.

Next, we set the subject of the message with:

msg['Subject'] = "subject line"

We set the sender email address with:

msg['From'] = sender

And we set the recipients’ emails with:

msg['To'] = ", ".join(recipients)

We combine the recipients into a string with join.

Finally, we send the email with:

s.sendmail(sender, recipients, msg.as_string())

Conclusion

To send email to multiple recipients using Python smtplib, we can use the sendmail method.

Sometimes, we want to make an immutable object in Python.

In this article, we’ll look at how to make an immutable object in Python.

How to make an immutable object in Python?

To make an immutable object in Python, we can create a named tuple.

For instance, we write:

import collections

Immutable = collections.namedtuple("Immutable", ["a", "b"])
i = Immutable(a=1, b=2)
print(i)

to call collections.namedtuple to create the Immutable class with a constructor that has a and b as parameters.

Then we use the Immutable constructor by calling it with a and b.

Therefore, i is Immutable(a=1, b=2) according to print.

Conclusion

To make an immutable object in Python, we can create a named tuple.