# given a list of ints this will get you the index of the largest value
idx = max(range(len(A)), key=A.__getitem__)

Django: get_FOO_display seems cool

get_FOO_display

from django.db import models

class Person(models.Model):
    SHIRT_SIZES = (
        ('S', 'Small'),
        ('M', 'Medium'),
        ('L', 'Large'),
    )
    name = models.CharField(max_length=60)
    shirt_size = models.CharField(max_length=2, choices=SHIRT_SIZES)

>>> p = Person(name="Fred Flintstone", shirt_size="L")
>>> p.save()
>>> p.shirt_size
'L'
>>> p.get_shirt_size_display()
'Large'

Django: refresh_from_db

Need to refetch a model from db?
# DO THIS
obj.refresh_from_db()# INSTEAD OF
updated_obj = Model.objects.get(pk=obj.pk)

Problems? Delete virtual environment and remake it.

Just a note for later. Trust me, it makes sense.

Matt’s Tips

avoid doing this…

1. Do not do “things” in an __init__
2. Do not assign something to self when you can instead make it a @property or could pass it as an argument.

helpful vim commands

map
help

could not connect to server: Connection refused

psycopg2.OperationalError: could not connect to server: Connection refused
Is the server running on host “127.0.0.1” and accepting
TCP/IP connections on port 57359?

Ran into this error at work. It turns out the user had deleted their known_hosts file. All that was required to fix it was to tunnel out to the ec2 instance and accept that ssh address.

Prod shell activate venv

source /opt/python/current/env
source /opt/python/run/venv/bin/activate
cd /opt/python/current/app
python manage.py showmigrations

(V)im (U)pdate

space + V + U

Updates vim plugins. Used it to fix a fuzzy find issue I was having.

space p

Allows you to paste from a register that stored what you copied (not what you may have inadvertently copied by deleting something).