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I think Django's ORM is just AMAZING. And as with every other tool, it has to be used wisely. First, it let's you get started quickly and prototype. You can wr
by santiagobasulto 2y ago
I think Django's ORM is just AMAZING. And as with every other tool, it has to be used wisely.
First, it let's you get started quickly and prototype. You can write unit tests, make sure everything is working as expected, then count queries and make sure you're being efficient with your SQL engine.
Second, and even more importantly, it's crucial in the definition of the app and the Schema. Thinking in high level "classes and objects" helps with the abstraction and the design of the apps. Even if you then default to raw SQU queries, thinking and building your model with class abstractions is huge.
Finally, there are some "tiny details" (but in my eyes, very important) that everybody oversees:
* Migrations: the way Django has designed migrations is just marvelous. We've migrated tons of data and changed the structure of our DB multiple times without any issues.
* Troubleshooting and "reporting": the ability to fire a quick shell, load a few models in Django's REPL, and do a few `.filters()` is for me key. On top of that, we add a Jupyter server connected to our read replica and we can do all sorts of reporting VERY QUICKLY. Not everybody needs a Data Lake :)
PS: We've ran Django sites accessed by millions of people per month. And we never had an issue with the ORM. Yes, sometimes I have to tell more junior devs that the gymnastics they're doing with `select_related` and `prefetch_related` can be more easily and effectively resolved with a query. But that's it. I'd say less than 1% of all the queries in our codebase have to be migrated to raw SQL.
- santiagobasulto 2y agoOne common pitfall with Django ORM's is that it makes it very easy the use of inheritance in models. But as we know, the "impedance mismatch" between OOP and the Relational model is a problem. It has happened that a dev in our team was populating an endpoint that used inheritance and when looking at the number of queries we were over 100. But the solution in those cases is just OUTER JOINs and CASE. Especially since we use Postgres in the backend and it works so well. So yes, there are some pitfalls, but they're greatly overshadowed by the advantages of the ORM.
- andybak 2y agoYou have to use the ORM with a bit of awareness of the query it it generates. Django provides plenty of tools and great documentation for reducing, combining and managing queries. It's not like it's a deep dark corner. It's like understanding memory allocation if you're writing c. It's just part of the job
- bruce343434 2y agoWe've had serious trouble with migration merges when two people work on different parts of the code, yet in the same module, and they both generate a "migration nr. 6" on their feature branches.
- andybak 2y agoNot at my desk but from memory, this is a something with a clearly documented "solution". I put that word in quotes because I don't want to imply it's a problem - it's just something you need to know how to handle.
- agumonkey 2y agoSomething in the official docs or more like shared through blogs or stackoverflow ?
- stavros 2y agoIt's in the standard docs: https://docs.djangoproject.com/en/5.1/topics/migrations/#version-control https://docs.djangoproject.com/en/5.1/topics/migrations/#ver... You just rename one of the two files, and add the dependency. If they touch the same fields, you obviously have to resolve that manually.
- DarkNova6 2y agoThat's the problem I have with Python mentality. Everything is great, you just need to know about the myriad of pitfalls and problems. A good environment makes problems obvious and and allows to communicate decisions clearly. This is the trap of the local maximum.
- exceptione 2y agoThere is one part in me that says to not destroy your positive mood, there is another part in me that wishes to yell at the pythonistas in general to look outside the Python world. Too often I come across Python projects that are hyped and when I dive into it I find it rather underwhelming to say it politely. Invariably it turns out that those people don´t know any other language than Python. I see that as a general problem; Python is the language for beginners this day with an endless amount of tutorials, but it seems lots of those starters don´t get to have a look outside the Python world. I fear this is getting an even bigger problem because AI models are trained on a vast range of Python, not because it is better, but simply because it is the PHP of these days. I don´t mean to imply that I know you have that "narrow profile". I agree that the value in Python is for quick prototypes in case you know Python well. Outside of that (at the risk of a language war), I think one does better look into modern .net core or the JVM for a general purpose, high quality and highly efficient language/platform. On the topic of ORM I think EF Core (.net core) and Doctrine (php) is strictly better.
- juahan 2y agoHow are those better?
- greenchair 2y agojob security for one big one
- za3faran 2y agoStatically typed languages, performance, refactorability, instrospection, debuggability, observability, the list goes on.
- jampekka 2y agoFor pythonistas reading this: JVM and .NET frameworks are better for large projects in the sense that they turn even the simplest projects into large messes of pointless byzantine buggy architecture, which in some circles is a sign of "high quality". Edit: That said, learning multiple programming languages (paradigms) is a very good idea. A reasonable dose of e.g. Java, .NET or C++ for example is great for understanding how programming languages and software should not be written. Learning modern JavaScript makes it obvious how Python really suffers from weak functional programming support, very bad performance and a horrible packaging system.
- DarkNova6 2y agoMay I ask, what experience do you have with other ORMs?