Question

I can’t work out what the appropriate model structure should be for this problem (simplified version to make explanation easier)

The goal is:

• a Person model with required fields
• When adding a person, you can optionally put in initial values for weight and height (one entry for each, default to 0)
• When values for height and/or weight are updated, the previous value is stored some where so the history can be viewed

I know I can have a separate model for height and for weight, linking them to Person by ForeignKey but it makes the admin presentation confusing and dis-jointed by allowing multiple entries at a time.

Alternatively, can I have height and weight as fields in Person (benefit of having clean list_view and inclusion of these fields in fieldsets), and when there is any update store the previous value into a different model? This model can then be listed to show some one’s history of values.

Any help is greatly appreciated.

Answer 1

Use ForeignKeys to height and weight models, then add a property to access that field

class Person(model)
    name = CharField()

    @property
    def weight(self):
        return self.weighthistory.latest().value


class Weight(model):
    value = IntegerField()
    date = DateTimeField()
    person = ForeignKey(Person, related_name="weighthistory")

class Height(model)
    value = IntegerField()
    date = DateTimeField()
    person = ForeignKey(Person)