"isaddress":false problem

[dlubom]

Hello, I have question: why in this query, for hotel in Rabat, city is marked as isaddress=false for city relation ?
API link: https://nominatim.openstreetmap.org/details.php?osmtype=N&osmid=2430191199&class=tourism&addressdetails=1&hierarchy=0&group_hierarchy=1&format=json

Nominatim link: https://nominatim.openstreetmap.org/ui/details.html?osmtype=N&osmid=2430191199&class=tourism

Is it bug ?

Second question, can I somehow get in this query https://nominatim.openstreetmap.org/details.php?osmtype=N&osmid=2430191199&class=tourism&addressdetails=1&hierarchy=0&group_hierarchy=1&format=json
not only chain of relation but also connected to relation places ?

[mtmail]

The HTML output is easier to read:

https://nominatim.openstreetmap.org/ui/details.html?osmtype=N&osmid=2430191199&class=tourism&addressdetails=1&hierarchy=0&group_hierarchy=1

is_address mean the place was considered to be part of the address (the address table) but another place was choosen. In this case "Agdal Riyad" was the "winner" for the admin_level=8 (city). With both admin_level=8 relations Nominatim needs to make a decision if https://www.openstreetmap.org/relation/2799215 or https://www.openstreetmap.org/relation/2799211 is more relevant. They cover the same area. I would say "Agdal Riyad" as arrondissement has the wrong admin_level set but a local mapper would need to determine that.

I'm not sure I understand the second question. When a relation and a node represent the same place then Nominatim merges the together internally. For example city of Rabat is https://www.openstreetmap.org/relation/2799215 and https://www.openstreetmap.org/node/299120862 Here Nominatim created https://nominatim.openstreetmap.org/ui/details.html?osmtype=R&osmid=2799215&class=boundary which has tags from both. It has the place=city from the node and admin_level=8 from the relation. Nominatim stores a linked_place_id value from the node to the relation but not from relation to the node:

select linked_place_id from placex where osm_type='N' and osm_id=299120862;
 linked_place_id
-----------------
       261186595

select osm_type, osm_id from placex where place_id = 261186595;
 osm_type | osm_id
----------+---------
 R        | 2799215

[dlubom]

Thank you, I send priv msg to author of this change: https://www.openstreetmap.org/relation/2799211/history

Now, lets come back to second question:

Let's phrase the question differently, more generally: I intend to periodically query Nominatim for various places, including the cities/states/countries associated with them. This will result in many requests, so I am considering setting up my own server.

Here's the question: do you see a possibility to automatically detect and correct errors similar to the one mentioned above on the fly, so as to obtain, despite the error, the city of Rabat for the above-mentioned hotel?

If this possibility requires code modification, that's fine with me.

[mtmail]

The /details endpoint is not allowed to be used by scripts or bots (https://nominatim.org/release-docs/latest/api/Details/), you need to setup your own server.
To find overlapping relations of the same admin_level I would use the Overpass API. It displays found areas transparent, if two overlap the color will be darker.

[out:json][timeout:100];
area["ISO3166-1"="MA"]->.country;
(
  relation["admin_level"="8"](area.country);
);
out geom;