wawa-dev

[wawa-dev]

uwsgi vs gunicorn

gunicorn is probably easier because of its simplicity

uwse uwsgi if you need complex settings

[wawa-dev]

reloading in Django shell

[wawa-dev]

how to set default cloud run region

gcloud config set run/region asia-northeast1

[wawa-dev]

what to do when migration fails

when migration fails,

comment URLs

comment context_processors

[wawa-dev]

multiple DBs

can specify multiple DBs in settings.py

can define which models will be saved in which DB in settings.py 's DATABASE_ROUTERS config

also can specify during save() method

[wawa-dev]

migration errors

https://create-it-myself.com/error-resolve/resolve-the-db-does-not-exist/#toc9

do not call DB models in class methods??

[wawa-dev]

custom managers 101

Basic usage:

managers are like helper methods for querysets

PollManager.objects.with_counts() prevents you from having to re-write .annotate(...) everywhere

you need to set objects = PollManager() in the Model class

Advanced Usage:

You can also

add more than 1 manager to a model

override the default .all() method

by adding authors = AuthorManager() in the Model class, and defining get_queryset() in the Manager class, you can call Person.authors.all() to get all People objects where role = "A"

Tips:

you can access the original Model in the Manager class by using self.model

don't use __getattr__ because it /can/ prevent managers from being shallow-copied (see here)

don't touch Model._base_manager or Model._default_manager if you're starting out (see here and here)

Links:

https://docs.djangoproject.com/en/4.2/topics/db/managers/

[wawa-dev]

how to count distinct

[wawa-dev]

dynamic Q objects

can use the |= operator, or write q_object.add

both OR and AND work

[wawa-dev]

TIL you can't specify label=None in your forms

you need to do label = "" instead

[wawa-dev]

business logic in forms + services

problem: my code contained business logic in both forms and services.

form: display only valid choices

service: ensure only the valid choices were sent

but given this post, I see that

form: display valid choices and validate user input is valid

service: assume input is valid, and handle data updates

[wawa-dev]

pass custom params to form

how the docs does it (albeit this is a formset, not a form)

[wawa-dev]

how to fix slow migrations

[wawa-dev]

Django writing models

[wawa-dev]

DB design patterns

L0 implementation : directly store value in table

L1 : store enum as a table

L2 : extract "Type" to a table

L3 : use mapping table

L4 : not really sure what this is