Allow only one instance of a model in Django

Question

I would like to control some configuration settings for my project using a database model. For example:

class JuicerBaseSettings(models.Model):
    max_rpm =         


        

Answer 1

If your model is used in django-admin only, you additionally can set dynamic add permission for your model:

# some imports here
from django.contrib import admin
from myapp import models

@admin.register(models.ExampleModel)
class ExampleModelAdmin(admin.ModelAdmin):

    # some code...

    def has_add_permission(self, request):
        # check if generally has add permission
        retVal = super().has_add_permission(request)
        # set add permission to False, if object already exists
        if retVal and models.ExampleModel.objects.exists():
            retVal = False
        return retVal