Django

related_name

Muss zwingend in ein Model rein, wenn es mehrere FKs aus dem gleichen Foreign Model hat. https://stackoverflow.com/questions/2642613/what-is-related-name-used-for

To add to existing answer - related name is a must in case there 2 FKs in the model that point to the same table. For example in case of Bill of material

@with_author 
class BOM(models.Model): 
    name = models.CharField(max_length=200,null=True, blank=True)
    description = models.TextField(null=True, blank=True)
    tomaterial =  models.ForeignKey(Material, related_name = 'tomaterial')
    frommaterial =  models.ForeignKey(Material, related_name = 'frommaterial')
    creation_time = models.DateTimeField(auto_now_add=True, blank=True)
    quantity = models.DecimalField(max_digits=19, decimal_places=10)

So when you will have to access this data you only can use related name

 bom = material.tomaterial.all().order_by('-creation_time')

It is not working otherwise (at least I was not able to skip the usage of related name in case of 2 FK's to the same table.)

Class Name / Model Name anzeigen

https://stackoverflow.com/questions/3599524/get-class-name-of-django-model print(Book.__name__)

Custom Widgets zusätzlichen Context / Daten hinzufügen

Weiß nicht genau warum custom Widgets nicht alle Daten gleich sehen können so wie normale Widgets. Im Zweifel einfach die get_context() Methode overriden:

In case of MultiWidget, similarly to @HenryM's answer, one can subclass get_context method and assign values like so:

def get_context(self, name, value, attrs):
    context = super().get_context(name, value, attrs)
    context["some_field"] = "some_value"
    return context

Which in template can be accessed by {{ some_field }}

https://stackoverflow.com/questions/56771884/how-to-add-additional-context-to-a-django-form-widget