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Comment by Alex3917 | Hacker News Reader

"what advantage does Django provide at this point in this project anymore?"

Documentation. I use Django but without any ORM and with Jinja2, so it's basically just Flask but with more stack overflow threads and more third-party software.

Is there any actual advantage that I would be getting by using Flask instead?

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Flask’s documentation is great, and the codebase is readable and small. The third party community is not as big as Django’s, but the 3rd party work is verified and approved by Armin (Flask and Jinja2 author). These guidelines encourage authors to publish higher quality code and better documentation. You couldn’t verify my claims, but this is my experience coming from Django a couple of years back. Django’s extensions are often very poor quality.

I’d also like to point out that Flask-Admin has come a long way with adapters for SQLAlchemy and at least one other ORM library. Very usable and extendible.

The advantages aren't really in using Flask, but being able to use a better ORM (or no ORM at all, just SQL abstraction) and template engine.

After working with Django ORM for a large project, I started to rethink the usefulness of models. It turns out just treating data as sets lends to a functional style and is simpler down the road.

> It turns out just treating data as sets lends to a functional style and is simpler down the road.

Could you elaborate on this or point in the direction of something that does? I'm pretty sure I get the gist but having some more meat to chew to make sure the perspective is fleshed out fully would be awesome.

The bottom line is, tying data to objects seems like an elegant idea, but in practice it sucks. ORMs introduce various problems, like statefulness (when the whole point of dealing with a database is atomicity) and mismatches (your data doesn't necessarly map to one row or one object, it doesn't have to). I'll try to give two examples.

Consider how people often write update code on Django:

    instance = Model.objects.get(id=some_id)
    instance.foo = bar
    instance.save()

This sucks a lot. It's doing two queries, and you have concurrency issues. This would be optimal, since it's atomic:

    Model.objects.filter(id=some_id).update(foo=bar)

But in this case, it's not instantiating any object nor triggering any signals, so what's the point of the ORM after all? We might as well just use a sane DB API.

Here's another place where Django's ORM fails:

    Model.objects.annotate(Count('foos')).filter(foos__lt=10)

This won't work. Django will complain 'foos' is not a field on the model - even though 'foos' is a column in the result set, and it's perfect valid to SELECT on it. I reported this as a bug, but because the ORM works with model definitions and the result set can contain any column, what the ORM is really supposed to do or not is murky, so it's WONTFIX. This is one instance where data doesn't map to an object and the ORM concept crumbles.

There are many other pain points with ORMs, and Django's in particular, but these are the highlights for me. For an elegant querying API, in my opinion, check out RethinkDB. It doesn't depend on schemas (therefore, ORMs) and it supports map/reduce semantics, which solves 100% of what you need to do with data.

You are mistaking about filtering an annotation.

   > Model.objects.annotate(Count('foos')).filter(foos__lt=10)

The only reason this doesn't work is because the property annotate creates isn't called `foos` by default. You just need to do this:

    Model.objects.annotate(foos=Count('foos')).filter(foos__lt=10)

and Django now knows to add a `HAVING COUNT(foos) < 10` clause.

I also use Django without any ORM and with Jinja2 and I'm taking baby steps towards completely abandoning Django and moving to Flask. For me, the primary benefit is that Flask being so much smaller and simpler than Django means you can understand the entire codebase without an extraordinary amount of effort.

I'm curious as to why you stick with Django (other than having projects already begun relying on it)? Without the ORM and with the templates, there's is not much I get out of Django.

"I'm curious as to why you stick with Django (other than having projects already begun relying on it)?"

I'm still a relatively new developer, so it was just easier to learn.

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