Geocoding - Different Postal Code In Response

Question

I am using the geocoding API passing postal codes (GB mainly) to validate if the postal code is valid or not (using the address_components and types where if it returns "postal_code" I take that it is valid) but I have found 2 issues.

Also is this the best method with Google Maps to validate a postal code?

1. I am posting https://maps.googleapis.com/maps/api/geocode/json?address=GU27YP&components=country:GB&key= where the postal code of GU2 7YP is sent and in the response it is giving me a different postal code (GU2 7UP). Why is this doing this, is it telling me that the postal code no longer exists (in 2016 it was removed) and now this other 1 has replaced it?

"address_components": [ { "long_name": "GU2 7UP", "short_name": "GU2 7UP", "types": [ "postal_code" ] },

2. I am validating postal code OL1 1NY (GB) and it returns a positive result but the postal code is no longer recognised by Royal Mail and was removed in Dec 2022. Is there a way to get Google to update it?

"address_components": [ { "long_name": "OL1 1NY", "short_name": "OL1 1NY", "types": [ "postal_code" ] },

For both issues I was expecting that would give me a response without a postal code match and would state the below as it does for another invalid postal code of ME4 4QQ

        "address_components": [
            {
                "long_name": "United Kingdom",
                "short_name": "GB",
                "types": [
                    "country",
                    "political"
                ]
            } 

Thanks

Answer 1

Component filtering is probably a better approach, at least it will prevent false positive results, e.g. returning GU2 7UP when requesting GU2 7YP:

https://maps.googleapis.com/maps/api/geocode/json?components=country:GB|postal_code:GU2%207YP returns ZERO_RESULTS because the components parameter enforces an exact match on postal_code:GU2%207YP

Whether a result is returned or not depends mostly on Google Maps data being accurate and up to date.

Another option could be using the new Address Validation API which broadly speaking provides 2 different "results":

1. address: how much of the input is confirmed to be (part of) a valid postal address
2. geocode: where would Google Maps locate the input (may or may not match the address).

More details in Understand the validation response.

As an example, the Address Validation Demo returns an address that essentially says "yes, GU2 7YP is a valid UK postal code", but the geocode returned is in fact GU2 7UP (Place ID: ChIJm7gwBcLQdUgRSfAroiN7KYw) because that's the (closet) one available.

Answer 2

Utilizing component filtering is a recommended strategy, as it minimizes incorrect results—like retrieving GU2 7UP when the goal is GU2 7YP. For instance, the link: https://maps.googleapis.com/maps/api/geocode/json?components=country:GB%7Cpostal_code:GU2%207YP yields ZERO_RESULTS due to its insistence on a precise match for postal_code:GU2%207YP. The success of getting the desired result largely leans on the precision and currentness of Google Maps' data.