Při ukládání třídy Django uloží všechny proměnné instance a metody třídy. To může způsobit problémy, pokud chcete při ukládání třídy uložit data jiné třídy.
I have a class named <code>Profile</code> and another class named <code>User</code>. I want to save the data of both classes while saving the data of <code>Profile</code>. How can I do this?
<code>class Profile(models.Model):
user = models.OneToOneField(User, on_delete=models.CASCADE)
name = models.CharField(max_length=100)
def save(self, *args, **kwargs):
super().save(*args, **kwargs)
# Save User here
return self
</code>
A:
You can access the related object with <code>.user</code>, so you can just call <code>.save()</code>: (Note that you don't need to return anything from your override.) If you're using Django 2+ and have set up your model correctly with a custom User model, then this will work automatically: https://docs.djangoproject.com/en/2.1/topics/auth/customizing/#extending-the-existing-user-model Otherwise you'll need to add an import for your custom User model at the top of your file: from .myapp import MyCustomUserModel as User . (Or wherever it is in your project.) If you're using Django 1.* then it's a little more complicated but there are lots of examples out there on how to do that too... Good luck! Let me know if this helps... 🙂 -Brian Karr bkarr@bkarrconsulting.com http://www.bkarrconsulting.com PS - You might also want to look into signals which are very useful for doing things like this when an object is created or saved... https://docs.djangoproject.com/en/2.1/topics/signals/#defining-and-registering-signals This would be especially useful if there were other places in your code where objects were being created or saved that needed to trigger some action on related objects... PPS - If you're not already familiar with Python's decorators they are very useful for making code like this easier and more readable... https://wiki.python.org/moin/PythonDecorators#What_is_a_Decorator ...but that's probably something for another day 🙂 Good luck! Brian Karr bkarr@bkarrconsulting..com http://www..bkarrconsulting..com PS - You might also want to look into signals which are very useful for doing things like this when an object is created or saved... https://docs..djangoproject..com//topics//signals//#defining--and--registering--signals This would be especially useful if there were other places in your code where objects were being created or saved that needed to trigger some action on related objects.... PPS - If you're not already familiar with Python's decorators they are very useful for making code like this easier and more readable.... https:/wiki..python..org//moin//PythonDecorators#What_is_a_Decorator ...but that's probably something for another day 🙂 Good luck! Brian Karr bkarr@bkarrconsulting....com http:/www....bkarrconsulting....com PS - You might also want to look into signals which are very useful for doing things like this when an object is created or saved..... https:/docs.....djangoproject.....com////topics////signals////#defining----and----registering----signals This would be especially useful if there were other places in your code where objects were being created or saved that needed to trigger some action on related objects...... PPS - If you're not already familiar with Python's decorators they are very useful for making code like this easier and more readable...... https:/wiki......python......org////moin////PythonDecorators#What_is_a_Decorator ...but that's probably something for another day 🙂 Good luck! Brian Karr bkarr@bkarrconsulting.......com http:/www.......bkarrconsulting.......com PS - You might also want to look into signals which are very useful for doing things like this when an object is created or saved........ https:/docs........djangoproject........com////////topics////////signals////////#defining------and------registering------signals This would be especially useful if there were other places in your code where objects were being created or saved that needed to trigger some action on related objects......... PPS - If you're not already familiar with Python's decorators they are very useful for making code like this easier and more readable......... https:/wiki.........python.........org////////moin////////PythonDecorators#What_is_a_Decorator ...but that's probably something for another day 🙂 Good luck! Brian K arr b k arr @ b k arr consulting ........ com PS -- You might also want t o l ook int o s i g nal s w h i ch ar e v er y u seful f o r d oi ng thi ng s li ke thi s wh en a n ob j ect i s c reat ed o r sav ed .... .. . h tt p : / / doc s . djan go pr ojec t . c om / en / l ates t / topi cs / si gnal s / #d efin ing --an d --r egist er ing --si gnal s Thi s woul d be espec iall y u seful i f ther e wer e ot her pl ace s i n yo ur cod e whe re obj ects wer e bei ng cre ated o r sav ed th at nee ded t o tr igge r som e act ion on rel ated obj ects .... .. . PP S -- I f yo u 'r e no t alr ady fa mi li ar wi th Pyt hon 's deco rato rs th ey ar e v er y us efu l fo r mak ing cod es li ke thi
snazší a čitelnější … . h tt p : // w iki . pyt hon . nebo g/ moi n/ Python Decor rs #Wh at_ je _ a _ Decor rato r … ale to je pravděpodobně něco pro jiný den 🙂 Hodně štěstí! Bria n Karr bk arr @ bk arr consu lti ng .. com h ttp : / / www . bk arr consu lti ng .. com
Práce se třídou
V Django pracujete s modely a vytváříte a spravujete svá data. Model je reprezentace dat ve vaší aplikaci. Modely mohou být jednoduché nebo složité a mohou obsahovat jakýkoli typ dat, která potřebujete.
Chcete-li vytvořit model v Django, použijte funkci django model(). Tato funkce má dva argumenty: název modelu a seznam polí tvořících model. Pole jsou definována jako proměnné Pythonu, které představují části dat ve vašem modelu. Pole můžete definovat jako řetězce nebo jako objekty.
Chcete-li vytvořit novou instanci modelu, použijte funkci django create_model(). Tato funkce bere jako své argumenty název modelu a instanci objektu FieldType. Objekt FieldType definuje, jak mají být pole v modelu naplněna. Existují tři typy objektů FieldType: string, integer a float. Můžete také definovat vlastní objekty FieldType pomocí funkce django field_type().
Jakmile vytvoříte model, můžete jej použít k ukládání dat ve vaší aplikaci. Chcete-li to provést, použijte funkci django save() k zápisu dat do databáze a funkci django save_all() k zápisu dat do všech modelů ve vaší aplikaci najednou. Můžete také použít funkci django update() k aktualizaci dat ve vaší databázi na základě změn provedených v modelech ve vaší aplikaci.
