#86 Make your NoSQL async and await-able with uMongo
Python Bytes - Podcast tekijän mukaan Michael Kennedy and Brian Okken - Maanantaisin
Kategoriat:
Sponsored by DigitalOcean: pythonbytes.fm/digitalocean
Special guest Bob Belderbos: @bbelderbos
Brian #1: responses
- “A utility for mocking out the Python Requests library.”
- From Sentry
Example:
import responses
import requests
@responses.activate
def test_simple():
responses.add(responses.GET, 'http://twitter.com/api/1/foobar',
json={'error': 'not found'}, status=404)
resp = requests.get('http://twitter.com/api/1/foobar')
assert resp.json() == {"error": "not found"}
assert len(responses.calls) == 1
assert responses.calls[0].request.url == 'http://twitter.com/api/1/foobar'
assert responses.calls[0].response.text == '{"error": "not found"}'
Bob #2: 29 common beginner Python errors on one page
- Decision trees / graphics are nice to digest and concise, it wraps a lot of experience on one slide
- Knowing about common errors can safe you a lot of time (the guide I wish I had when I started coding in Python)
- Reminded me of struggles I had when I started in Python, for example TypeErrors when converting suspected ints to strings, regexes before discovering raw strings
- It made me think of related issues newer Pythonistas face, for example “I am reading a file but getting no input” can be translated to “I am looping over a generator for the second time and don’t get any output”
- Made me realize that some things are subtle, like comparing 3 == “3” or require good knowledge of stdlib (sorted returning new sequence vs inplace sort() for example)
- Made me reflect on how much hand holding you would give your students when teaching. Part of the learning is in the struggle.
- About the source, I like seeing Python being taught in all different kind of domains, in this case biology.
Michael #3: μMongo
- μMongo is a Python MongoDB ODM.
- It inception comes from two needs:
- the lack of async ODM
- the difficulty to do document (un)serialization with existing ODMs.
- a few design choices:
- Stay close to the standards MongoDB driver to keep the same API when possible: use
find({"field": "value"})
like usual but retrieve your data nicely OO wrapped ! - Work with multiple drivers (PyMongo, TxMongo, motor_asyncio and mongomock for the moment)
- Tight integration with Marshmallow serialization library to easily dump and load your data with the outside world
- i18n integration to localize validation error messages
- Free software: MIT license
- Test with 90%+ coverage ;-)
- Stay close to the standards MongoDB driver to keep the same API when possible: use
- async / await support through Motor
Brian #4: Basic Statistics in Python: Descriptive Statistics
- Cool use of Python to teach basic statistics topics.
- Includes code snippets to explain different concepts like min, max, mean, median, mode, …
- However, after you understand the math, DON’T write your own functions.
- use built in Python functions and the statistics library built in to Python (or numpy if you are on older Python versions).
Example from article:
sum_score = sum(scores)
num_score = len(scores)
avg_score = sum_score/num_score
avg_score
>>> 87.8884184721394
Using built in:
>>> x = (2, 2, 3, 100)
>>> min(x), max(x)
(2, 100)
>>> import statistics as s
>>> s.mean(x), s.median(x), s.mode(x)
(26.75, 2.5, 2)
>>> s.pstdev(x), s.pvariance(x)
(42.29287765097097, 1788.6875)
>>> s.stdev(x), s.variance(x)
(48.835608593184, 2384.9166666666665)
Bob #5: Strings and Character Data in Python
- Everything you need to know to work with strings and more …
- Similar to that great itertools article you shared some weeks ago: exhaustive overview
- Nice re-usable code snippets and explanation of basic concepts, ideal for beginners but you likely will get something out of it, few useful bites:
- Instead of
try int(…) except
, you can useisdigit()
on a string - You can use
isspace()
to see if all characters of a nonempty string are whitespace characters (' '
, tab'\t'
, and newline'\n'
) - It’s easy to make a header in your Python scripts:
- Instead of
>>>> 'bar'.center(10, '-')
'---bar----'
- Replace up till n occurrences:
>>>> 'foo bar foo baz foo qux'.replace('foo', 'grault', 2)
'grault bar grault baz foo qux'
- Strip multiple characters from both ends of a string:
>>>> 'www.realpython.com'.strip('w.moc')
'realpython'
- Add leading padding to a string with `zfill`:
>>>> '42'.zfill(5)
'00042'
- This also reminded me of Python’s polymorphism, for example str.find and str.index work on both strings as well as lists
>>> 'foo bar foo baz foo qux'.index('baz')
12
>>> 'foo bar foo baz foo qux'.split().index('baz')
3
>>> 'foo bar foo baz foo qux'.count('foo')
3
>>> 'foo bar foo baz foo qux'.split().count('foo')
3
Michael #6: PEP 572: Assignment expressions accepted
- Whoa, check out that twitter conversation
- Splits 2 statements into an expressions (so they can be part of list comprehensions, etc).
- Not sure I like it but here you go:
Example:
# Handle a matched regex
if (match := pattern.search(data)) is not None:
...
Contrast old and new:
# old
if self._is_special:
ans = self._check_nans(context=context)
if ans:
return ans
# new
if self._is_special and (ans := self._check_nans(context=context)):
return ans
Our news:
- Michael: New course coming! Data-driven web apps in Pyramid
- Bob: Be sure to visit PyBites Code Challenges
- Brian: More Test and Code episodes coming!