Am 25.02.23 um 17:58 schrieb Silent Coder:
Hi Christian and Group,
I'm new to Django and still learning the ropes, but I'm curious to
know what the use cases for something like this might be.
I don't want to use django-developers for this topic more than intended
(django development); I'll answer this, but if you have further
questions, just send me a PM or use django-users - ok?
The main reason is Django does not allow apps to be "plugged" into a
main application. If you want to extend an application woth other
plugins, you are alone...
GDAPS tries to fill this gap.
I started this because I want to create a medical application that has a
"core" app, and can be extended using plugins like "laboratory",
"demographics/statistics", "ledger" etc.. Those all are apps that fit
into the main system, with own models and views, but use the core's
templates, models, etc.
If you want to create applicances that can be easily extended by
plugins, you can do this with GDAPS by just installing the app with pip
and restart the server. With Django alone, you would have to add all the
apps manually into settings.py, and step through dependency
installation, etc.
GDAPS tries to create a framework for that, at least for the backend (+
Django templates). No frontend supported any more (Vue.js was in
exploration).
Hope you can see what I want to achieve.
Christian
On Thursday, February 23, 2023 at 4:14:52 PM UTC-6 Christian González
wrote:
Am 23.02.23 um 17:09 schrieb Jörg Breitbart:
Ah sorry for the fuzz, I read too much into your idea and jumped
to the conclusion, that you want to extend INSTALLED_APPS at
runtime.
no prob ;-)
As you already pointed out, the proper app ordering might be a
bigger issue for an automated app discovery. Not sure how you
solved that, this might need some tree balance logic, but the
question remains, where to get the info "xy must be loaded
before/after z" from in the first place. Ideally apps should be
loading position independent, but thats not always the case, and
you might even run into edge cases, where a proper loading
strategy cannot be found due to incompatible before/after
requirements.
I am exploring 2 ways of adding app strings to INSTALLED_APPS.
Code says more than words:
class PluginManager: ... @classmethod def
alter_installed_apps(cls, installed_apps: list[str], group: str)
-> list[str]: """Lets plugins update INSTALLED_APPS and add their
own apps to it, in arbitrary order. Call this method directly
after your settings.INSTALLED_APPS declaration. """
I'm not sure if altering the passed list is better, or returning a
new one. would be more explicit to see what it does.
The method
1. searches for an *alter_installed_apps* method in the main
plugin module, which takes the INSTALLED_APPS as first argument,
and calls it. So I give the plugin itself the possibility to place
itself (and evtl. needed other modules) at indexes of the
INSTALLED_APPS list *they* need and find appropriate. This should
work well for many apps that have special requirements like
"should be placed after django.contrib.staticfiles", but does not
cover real dependency checking, especially does not cover
inter-dependencies of 2 plugins - the first loaded plugin does not
know about the second, as at time of calling the first one,
INSTALLED_APPS does not contain the second one.
2. if this does not exist, it searches for an INSTALLED_APPS list
in the main module as stated earlier, for dumb modules that just
need to be loaded, no matter which order. This list is plainly
appended to the main INSTALLED_APPS.
At time of calling plugin implementations via their hooks, they
provide "weight" attrs and get ordered by this attr when iterating
over them. So each interface hook can have it's own ordering,
which works perfectly.
But that doesn't solve the dependency resolution problem of
INSTALLED_APPS. One of my solutions is: Use Python's way: I
declare dependencies in pyproject.toml, so dependency resolution
is done by pip. And in Django, I can already be sure everything is
installed as intended, and just order INSTALLED_APPS like I want to.
But it's not perfect, I know.
So thanks Jörg for your helpful comment. I wasn't quite sure about
if I did something stupid.
And thanks for your all engaging in Django, it's really a great
piece of software.
Yours,
Christian
-- Dr. Christian González https://nerdocs.at
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