How to get sum of all inline fields in django?

Question

Django

There are two classes:

class Foo(models.Model):
  ...
  my_max_total = models.IntegerField()

class Bar(models.Model):
  total = models.IntegerField()
  my_foo = models.ForeignKey(Foo)

class BarInline(admin.TabularInline):
    model = Bar

class FooAdmin(admin.ModelAdmin):
    inlines = (BarInline, )

How to check when editing a Bar, including inlines, that the total sum of totals of all Bars of one Foo does not exceed my_max_total specified in it?

Answer 1

Set a custom admin form and override its clean method. In this method, check everything you need and in case of an error, throw the forms.ValidationError exception.