#django

Hey I am new and i want to contribute

Try starting here https://docs.djangoproject.com/en/dev/internals...

hi all

this is my model

and i want to make 2 type limit

like every model could have 4 ogrenci

and every ogrenci can be only one PansiyonOda member

It's not how ManyToMany works

can i controlling this with django models(database) or with my view fucntion or etc

You want OneToOne for second part

er, no

ForeignKey I meant

ForeignKey is workng different i think

i want to make a limit for ogrenci. Like, only 4 ogrenci can be a member for this model

I said that for second point you gave

oh sorry

For count limit you'll have to write some custom check logic I guess

Even if you can enforce it with raw sql on DB level (I don't know if you can) you'll still need proper validation and error handling in python

I don't think ORM has built-in for count limits

I’m seeing some strange behavior. I have an abstract model (A) that has two fields. I then have another abstract model (B) that inherits from A but doesn’t add any fields. And then I have a “real” model (C) that inherits from B. And but doesn’t have the two fields from A — why is that?

jobelenus: can you dpaste your models?

GinFuyou: https://stackoverflow.com/questions/20203806/li...

i gues i have to do like this for limit

eribol, I don't think it's a best way to raise exceotions in a signal

hrmm one sec I may have misunderstood my traceback

GinFuyou: i couple advice there and so on

eribol, also as I said, don't use m2m, it's not use case you have described

ForeignKey for every ogrenci?

4 field i need for it

Ogrenci has only one PansiyonOda? Then yes, FK

i though opposite :D PansiyonOda has 4 ogrenci :)

it sounds nice

i will try it

FK is one-to-many

so put it to Ogrenci and then you can even try out clean() method on it

hmmm

silly me

i should though this before

eribol: You really want to have some method in your model where you attach orengci members.

eribol: and in that method you first check that is the number of orgenci less tahn 4 to allow adding. If not do something that suits in your workflows.

eribol: And then just make sure that you never directly assign that m2m.

Will post_-signals in Django hook AFTER a transaction is complete or within the transaction. I ask because a rollback could lead to problems

ovalseven8: That really depends on your transaction model.

By default django runs in autocommit mode.

jtiai: thank you for your advice

i cant change my model anymore but can control it

eribol: Yoy don't need to change your model, just add methods to it.

If you don't have control of that model (it's 3rd party) you still can use proxy models to achieve what I described.

Can someone explain me what this is for? https://docs.djangoproject.com/en/2.1/howto/cus...

I do not understand the description

Why do you care?

Are you going to output SQL from your custom management command?