pawl

1. download ubuntu image for orangepi zero LTS: http://www.orangepi.org/downloadresources/
2. flash with etcher
3. fiddle with USB to TTL, gave up on trying to get that to work
4. plug ethernet into switch
5. ssh orangepi@
6. password orangepi
7. couldn't successfully apt-get update upgrade, getting E: Unable to acquire the dpkg frontend lock
8. download armbian image for orangepi zero LTS: http://www.orangepi.org/downloadresources/
9. flash with etcher
10. armbian-config

pawl

# See full example: https://github.com/pawl/django_modelchoicefield_caching/blob/master/myapp/views.py#L31-L51
    for song in playlist:
        form_data = {'title': song["title"], 'artist': song["artist"]}
        song_form = forms.SongFormWithModelChoiceField(data=form_data)
        song_form.is_valid()  # runs a query to get the ModelChoiceField queryset each time

    print('ModelChoiceField - query count AFTER validating all songs:',
          len(connection.queries))  # 5 queries

    # query for choices outside of the loop to prevent unnecessary queries

pawl

In my opinion, one of django's biggest gotchas is using RelatedManager.set with models that have non-nullable ForeignKey fields.

Example

Models.py (with a one-to-many relationship and a non-nullable ForeignKey):

class Reporter(models.Model):
    name = models.CharField(max_length=255)


class Article(models.Model):

pawl

cd ~
mkdir mysite
virtualenv .venv -p `which python3`
source .venv/bin/activate
pip install django
django-admin startproject mysite
cd mysite
python manage.py startapp myapp

pawl

server {
    listen 80;
    listen [::]:80;

    root /var/dav/webdav_root;

    # dav allowed method
    dav_methods     PUT DELETE MKCOL COPY MOVE;
    # Allow current scope perform specified DAV method
    dav_ext_methods PROPFIND OPTIONS;

pawl

Based on:

• https://github.com/lucafabbri/HiGrow-Arduino-Esp/blob/master/HiGrowEsp32/HiGrowEsp32.ino
• https://github.com/Syzygianinfern0/Telegram-NodeMCU/blob/5867e792739a368a75aeb43510ba9839f94ad132/Telegram_Bot.ino

Must get ArduinoJSON 5.x

pawl

This is a test to see if psycogreen is necessary to run sqlalchemy + gevent + psycopg2 concurrently.

benchmark command (concurrency of 10)

ab -n 10 -c 10 127.0.0.1:8080/wait

psychopg2 - sync worker (expecting concurrency of 2)

gunicorn -b 127.0.0.1:8080 -w 2 test:app

pawl

service PingPong {
    string ping(),
}

pawl

# demonstrates the issue fixed in: https://bitbucket.org/zzzeek/sqlalchemy/issues/3907

from sqlalchemy import create_engine, Column, Integer
from sqlalchemy.orm import scoped_session, sessionmaker
from sqlalchemy.ext.declarative import declarative_base

engine = create_engine('mysql://root@localhost/test?charset=utf8mb4',
                       convert_unicode=True,
                       echo=True)
session = scoped_session(sessionmaker(autocommit=False,

pawl

from collections import defaultdict

from sqlalchemy import create_engine, Column, ForeignKey, Integer
from sqlalchemy.orm import relationship, scoped_session, sessionmaker
from sqlalchemy.orm.attributes import set_committed_value
from sqlalchemy.ext.declarative import declarative_base

engine = create_engine('mysql://root@localhost/test?charset=utf8mb4',
                       convert_unicode=True,
                       echo=True)