Django MVT design: Should I have all the code in models or views?
Experienced Django users seem to always err on the side of putting code in models. In part, that's because it's a lot easier to unit test models - they're usually pretty self-contained, whereas views touch both models and templates.
Beyond that, I would just ask yourself if the code pertains to the model itself or whether it's specific to the way it's being accessed and presented in a given view. I don't entirely understand your example (I think you're going to have to post some code if you want more specific help), but everything you mention sounds to me like it belongs in the model. That is, creating a new Operation sounds like it's an inherent part of what it means to do something called add_operation()!
I'm pretty novice so I'll try to explain in a way that you can understand what I mean.
I'm coding a simple application in Django to track cash operations, track amounts, etc.
So I have an Account Model (with an amount field to track how many money is inside) and an Operation Model(with an amount field as well).
I've created a model helper called Account.add_operation(amount). Here is my question:
Should I include inside the code to create the new Operation inside Account.add_operation(amount) or should I do it in the Views?
And, should I call the save() method in the models (for example at the end of Account.add_operation() or must it be called in the views?)
What's the best approach, to have code inside the models or inside the views?
Thanks for your attention and your patience.