Constituency town export includes towns that are in the wrong county / country

[c6andy]

The constituency->town mapping importer (ImportConstituencyTownMappingsCommand.php) matches towns to constituencies based on names alone (i.e. no IDs):

constituency-explorer/app/Console/Commands/ImportConstituencyTownMappingsCommand.php

Line 32 in 290fe7d

$town = Town::where('name', $row['town_name'])->first();

This will cause some towns to be mismatched, because there are often towns with the same name in different places (e.g. there are 12 towns called “Wick” in the database).

Given we have lat-long values for towns, we could instead run the towns through one of the mappers mentioned in the README to get the constituency. I guess that hasn’t been done because some towns straddle more than one constituency, and that’s why the relationship is many-to-many?

[jacksegal]

Recreate:

• https://campaign-lab-constituency-explorer.c6digital.dev/constituency/E14001115
• Download Towns
• Wick shows as "Scotland"
• But... why do we even have the Town map? Why don't we just use the raw Towns? Is it a many-to-many?

[c6andy]

Why don't we just use the raw Towns? Is it a many-to-many?

I thought I could check this from the towns-map.csv data, but of course that’s wrong. E.g. Wick appears in towns-map.csv twice, but it’s not obvious from the towns-map.csv data alone whether that’s the same Wick.

I think we’d be better off mapping uktowns.csv to constituencies and using that. Then optionally refactoring to scrap the many-to-many relationship. That would fix this ticket. It might result in missing off some towns that span multiple constituencies, but the current data is incomplete anyway so it wouldn’t be any worse than the current situation.