The route /corporations/{corporation_id}/customs_offices/ gives me a list of all customs offices a corporation owns. I also get the system_id as well an office_id.
But I wonder how to gather the information about the planet the custom office belongs to.
Let me summarize the solution: /corporations/{corporation_id}/customs_offices/
gives you a office_id
You may get the Custom Office Name and Location as a string with /corporations/{corporation_id}/assets/names/
you’ll get a response like "item_id": 1032123456789, "name": "Customs Office (Jita IV)"
With a regex or string functions it’s now easy to extract the location and to resolve the location_id.