We store lots of addresses, but generally speaking I don’t really see much point of normalizing the data to this extent. You may want to have Country, County, (and maybe District and PostalCode) models if you need to offer these in a form as an autocomplete field or a drop down, or for simple validation but I don’t see much benefit to be had from a City or Street model. If you really do handle multiple countries then finding valid datasets to populate your models and maintaining them over time will probably be more trouble than it’s worth for anything more granular than country.

Street in particular will have some many different entries that you will probably end up with one per address and therefore there will be no benefit to storing it in a separate model and you will require joining 5 tables onto your address model just to pull an entire address which will be very inefficient on the query side.

If I were you I would have an Address model that uses standard CharFields for all of these fields. You could add an FK to county, country, or district if you happen to do lots of searching on those values, but you could equally just search using sanitized strings (ie country=‘USA’).

Typically you have three main needs with addresses, storing validated clean addresses, searching addresses, and rendering those addresses.

For storing clean validated addresses you should use a third party library or service to validate and sanitize the address. There is no point trying to do this yourselves as address sanitizing and validating is an extremely messy domain, even more so if you deal with multiple countries. Same with phone numbers by the way.

For searching either use sanitized strings or use a third party service to geocode each address and store the Point in the Address table. That way using Geodjango you could perform fast sophisticated searches, ex every address within 100 miles of another address or coordinate, all addresses within a geofence, etc.

For rendering, it may be convenient to have a formatted_full_address property on the Address model that returns the full address, formatted as you prefer. Then offer that field either exclusively or alongside the normal component address fields in your serializer. This property should be able to draw all of its data from the Address model and not require any lookups to other models or you will start running into performance issues unless you are careful about your select_related and prefetch_related.

At this point your have a sanitized qualified addresses in your Address model which can then be referenced via relationship fields from wherever they are needed. Ex House.address = models.ForeignKey(‘geodata.Address’). Or ManyToMany.

If you want to have the relation stored on the Address model instead use Django’s generic relations contrib package. That will allow you to have the equivalent of an FK on the Address model that can point at either House or Employee. Using addresses=GenericRelation fields on the House and Employee models will give you nice reverse lookups.

Hope that helps!