python manage.py makemigrations <app>

Will create migration files for all the apps if the app was not indicated.

class Award(models.Model):
    name = models.CharField(max_length=200, unique=True)
    ...
 
    @classmethod
    def pre_save(cls, sender, instance, **kwargs):
        ...
 
pre_save.connect(Award.pre_save, sender=Award)

from django.contrib.auth.models import User
from django.db.models.signals import post_save
from django.dispatch import receiver
 
class Profile(models.Model):
    user = models.OneToOneField(User, on_delete=models.CASCADE)
    bio = models.TextField(max_length=500, blank=True)
    location = models.CharField(max_length=30, blank=True)
    birth_date = models.DateField(null=True, blank=True)
 
@receiver(post_save, sender=User)
def create_user_profile(sender, instance, created, **kwargs):
    if created:
        Profile.objects.create(user=instance)
 
@receiver(post_save, sender=User)
def save_user_profile(sender, instance, **kwargs):
    instance.profile.save()

Proxy models are used to modify Python behaviour of a model by extending a model class. Database tables aren't generated for proxy models. So you can't use a proxy model for AUTH_USER_MODEL.

class Badge(models.Model):
    name = ...
    color = ... # gold/silver


class GoldBadge(Badge)
    class Meta:
        proxy = True

    def award(self, user):
        # award a gold badge to user

class SilverBadge(Badge):
    class Meta:
        proxy = True

    def award(self, user):
        # award a silver badge to user

The auto_now_add will set the timezone.now() only when the instance is created, and auto_now will update the field everytime the save method is called.

class Invoice(models.Model):
    description = models.CharField(max_length=255)
    status = models.CharField(max_length=10)
    vendor = models.ForeignKey(Vendor)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

Model:

cover = models.ImageField(null=True)

Template:

{% if object.cover %}
<img src="{{ object.cover.url }}"></img>
{% endif %}

Config:

MEDIA_URL = '/media/'
MEDIA_ROOT = os.path.join(BASE_DIR, '../media')

Urls:

from django.contrib.staticfiles.urls import static
from django.conf import settings
 
urlpatterns += static(settings.MEDIA_URL, document_root=settings.MEDIA_ROOT)

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)

Get its values

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

id = models.UUIDField(primary_key=True, default=uuid4, help_text="Unique ID for this particular video")

import calendar
 
...
 
class MyModel(models.Model):
    ...
 
    MONTH_CHOICES = [(str(i), calendar.month_name[i]) for i in range(1,13)]
 
    month = CharField(max_length=9, choices=MONTHS_CHOICES, default='1')

from django.apps import apps
apps.get_model('users', 'BaseUser')

reg = Work(title=random_string_generator(random.randint(5, 15), True),
           license=License.objects.order_by('?').first(),
           description=random_string_generator(random.randint(200,2000), True),
           created=str_time_prop(prop=random.random()),
           creator=User.objects.order_by('?').first())
reg.save()

find . -path "*/migrations/*.py" -not -name "__init__.py" -delete
find . -path "*/migrations/*.pyc"  -delete

#!/bin/sh

export PGPASSWORD=mysecretpassword
export DATABASE=puma

find . -path "*/migrations/*.py" -not -name "__init__.py" -delete
find . -path "*/migrations/*.pyc"  -delete

dropdb -h 127.0.0.1 -U postgres $DATABASE
createdb -T template0 -h 127.0.0.1 -U postgres $DATABASE

python manage.py makemigrations
python manage.py migrate

psql -h 127.0.0.1 -U postgres -d $DATABASE -c "INSERT INTO public.pumapp_user (password,last_login,is_superuser,username,first_name,last_name,is_staff,is_active,date_joined,email,current_project_id) VALUES ('pbkdf2_sha256$100000$8RoYX0VMbGIY$OZrZowL8A4pR/wgE/ggy7KOSAU82068MEG3tiZHV70I=',NULL,true,'admin','','',true,true,'2019-01-31 08:22:29.609','admin@a.com',NULL);"
psql -h 127.0.0.1 -U postgres -d $DATABASE -c "INSERT INTO public.redmine_auth_redmineconfig (url) VALUES ('https://redmine.gtd.es');"