Nominatim: Looking up a street address by house number and postcode in the Netherlands

Do you mean that Nominatim never includes the "ES" of the postcode when I search for "9718ES"? If this is the case, how come Nominatim does return "9718ES" when I search for the street address, rather than just "9718"? I would like to patch Nominatim to allow for postcode lookups in the Netherlands (I already forked it), but I have no clue on how its geocoding algorithm currently works. I tried to grasp it in Geocode.php but find it somewhat difficult to understand.

There are nodes with the tag "postal_code". This has in the Netherlands mostly only the 4PP code. Until recently this was basically the only postcode data around here. Now with the BAG data in OSM we have lots of nodes (and ways) with the tag "addr:postcode". However these are only seen as a postcode POI for the indexing when they are included for another reason. E.g. because they are put on an ATM.

• Another Melkweg.
• It's administrative area (only 4 postcode children).
• It's guestimate postcode point.

If you search with a housenumber (Melkweg 34, Hellevoetsluis) it notices the addr:postcode on the end result and decides that is better (because explicitly tagged) than the guestimate. Notice the greyed out guestimate and the fact the used postcode has no ID in the index.

On top of all this there is the search string parser. How should it know what is a postcode in the following string: "Melkweg 34 3225VE Hellevoetsluis". It's immediately obvious for a Dutchman, but for a computer it could equally be just a long housenumber.

Sorry, I can't help you with the coding.

It's been two years, the "No this is currently not possible." is still correct?

It's been seven years. Unfortunately it still isn't possible.

@cartinus, it can be immediately obvious for a computer too. Four digits followed by two letters can only be a postcode, in the Netherlands. So with RegEx it shouldn't be a problem.

For example:

// This will return the postcode IF the address string contains one, IF not it will return an empty string

$address_string = "Melkweg 34 3225VE Hellevoetsluis";

$postcode = preg_match("/\d\d\d\d[a-z][a-z]/i", $address_string, $matches) ? $matches[0] : "";

echo $postcode;

The only thing left to do is check if the address country is the Netherlands. Nominatim already seems to be able to do this with just the postcode.

Therefor it's only a matter of implementing it. The code exists, it works, it only needs someone who knows Nominatim to add it.

If you're that someone, please add this option, it would be incredibly useful to us.

@WebDev_21 you obviously have little idea how OSM software develops, or the resources available to do it. No-one is going to drop everything to implement an obscure tweak just for The Netherlands. Either fork the project and do it yourself submitting a pull request for it to be pulled back into core, or pay someone to do it. Don't tell volunteers "it's only a matter of implementing it", the same is true of nuclear fusion!