The ORM is really not good in my opinion because it is ActiveRecord'ish and has all its downsides. I wouldn't use Django for any moderately complex domain. But even with simpler CRUD style apps I don't really see the point in it.
It can take a while to wrap your head around what fields get used in aggregates and the like, but when working with big models with like 65 fields and juggling a bunch of stuff, not having to futz with serialization/deserialization and "just" expressing your problem in the dumb way is nice.
I want to say this all comes back to bite you in the end but honestly it's more just having wide tables that comes to bite you. A service layer wouldn't really save you. Meanwhile you save yourself a bunch of tedium in the mean time
And if you can't make the ORM make the SQL query you want, you can just write it as a SQL query, like this godawful monstrosity:
x = Site.objects.raw("select id, name, lat, lon, 111.045*degrees(acos(cos( \
radians(latpoint))*cos(radians(lat)) \
*cos(radians(lngpoint)-radians(lon)) \
+sin(radians(latpoint))*sin(radians(lat)))) \
as distance from sites_site join \
(select %s as latpoint, %s as lngpoint) as p on 1=1 \
order by distance limit 5", [float(lat), float(lon)])
I am in roughly equal parts proud of and horrified by this creation.
for function calls, look at django.db.models.functions, you can find a bunch of stuff in there or create custom ones super easily (like "two lines of codes" easily)
I mean you have a thing that works in theory so it's a bit of navel gazing, though.
I was really just going to try and wrap it in a function to stick in the model so I can say something like Site.objects.get(id=thing).distance_from(lat,long) in.
But, now the bit that I was calling that from is actually being done from a websocket handler, and that's written in Go because Django and websockets seems very complex.
How would you have approached it?
Kinda took until Facebook showing off Hacklang in 2014 for people to believe in getting more canonical programming features into PHP and make it more performant. So it would have been a good decision if one could predict 10 years into the future, but nobody can.
> Models being passed around everywhere, queries happening everywhere.
No, as a developer you still need to be 100% aware of the underlying queries and potential performance issues. No excuse for N+1 problems. ORM is not an excuse to be lazy, but I admit it will probably catch quite a few developers.
Those same developers would probably make a mess out of any other framework or technology though.
It definitely takes a bit of discipline. The key layers are somewhat easy to manage—middleware, context processors, views, template tags—but I’ve seen some hairy lasagne further obscuring where the queries happen on top of that. A well-documented abstraction can be useful, but if it is possible to keep it simple and obvious then that’s the way to go.
(Third-party dependencies can further complicate things, but at least you can expect a library using ORM to be in the installed apps list.)
It's highly productive if you do it right.
Every time ORMs get discussed, it seems to be dominated by people who are like "but my app has 5 billion concurrent users doing 2 million requests per second and if there's an extra 5ms on my requests, it will all explode!" and can't comprehend that not everyone is building the same kind of systems all the time. Great, maybe an ORM isn't appropriate for your situation.