Multiple osm_tag to filter Photon result

[marcus-at-localhost]

Hi,
it's possible to add multiple osm_tag parameter to filter photon results for osm_key and osm_value fields. https://github.com/komoot/photon/blob/master/README.md#user-content-filter-results-by-tags-and-values

To filter all shops from the result set I would do this.

M.geocoder = L.Control.geocoder({
	geocoder: L.Control.Geocoder.photon({
		geocodingQueryParams: {
			limit: 8,
			osm_tag: '!shop'
		}
	})
})

Which translate to: https://photon.komoot.de/api/?q=kaufland&limit=8&osm_tag=!shop

But of course it is not possible to have multiple osm_tag params
https://photon.komoot.de/api/?q=kaufland&limit=8&osm_tag=!shop&osm_tag=!landuse
since same keys are getting merged:

geocodingQueryParams: {
	osm_tag: '!shop',
	osm_tag: '!landuse',
}

And when I look at the utils/getJSON function I don't see how to make this work with only changing the Photon provider plugin.

Any idea?

[simon04]

Specifying two identical keys for the JavaScript object cannot work, since the second one overrides the first one. An option would be to specify an array of osm_tag, but this function https://github.com/Leaflet/Leaflet/blob/6708981c7474109211162103037b28c26724ed51/src/core/Util.js#L145-L156 does not handle arrays.

geocodingQueryParams: {
	osm_tag: ['!shop', '!landuse']
}

We could either file a PR for Leaflet, or copy & modify this function in leaflet-control-geocoder.

[marcus-at-localhost]

I think photon is not really standard conform here. The right way to do it is osm_tag[]=x&osm_tag[]=y so in this case this hack should be made in the leaflet-control-geocoder lib. I'm not really familiar with the build process of this lib, else I would give it a shot. Maybe I'll try it.
Edit: I forked it, and I have no clue how to test changes. :/

[marcus-at-localhost]

What if params can be also a string and the query gets build in the provider plugin for this special case?

export function getJSON(url, params, callback) {
 //...
   if (typeof params === 'object') {
        url += L.Util.getParamString(params);
    }else{
       url += params;
    }
  xmlHttp.open('GET', url, true);
 // ...
}

[simon04]

Since 2d06ebf, the following should work and yield the URL ...&osm_tag=!shop&osm_tag=!landuse:

geocodingQueryParams: {
	osm_tag: ['!shop', '!landuse']
}