properties with null values get dropped

[stvno]

I've got a large GeoJSON with 1014963 features with several properties which contain NULL values together with actual numeric values. These properties get (silently) dropped from the resulting mbtiles.

Feature with a gloei-value:

{ "type": "Feature",
   "properties": 
      { "id": 10596379, "gloei": 1 }, 
  "geometry": 
     { "type": "MultiPolygon", "coordinates": [ [ [ [ <geom> ] ] ] ] }
},

and without

{ "type": "Feature",
   "properties": 
      { "id": 10615538,  "gloei": null },
   "geometry": 
      { "type": "MultiPolygon", "coordinates": [ [ [ [<geom> ] ] ] ] } 
}

I specifically told tippecanoe to include 'gloei':
./tippecanoe -o licht2.mbtiles out.json -y gloei

However the resulting mbtiles doesn't include the gloei property
This is its tilejson, courtesy of tessera:

{"scheme":"tms","basename":"licht2.mbtiles","id":"licht2","filesize":218353664,"name":"licht2.mbtiles","description":"licht2.mbtiles","version":"1","minzoom":0,"maxzoom":14,"center":[5.174561,52.221069,14],"bounds":[3.358925,50.750881,7.225992,53.534755],"type":"overlay","format":"pbf",
"vector_layers":[
    {"id":"out",
      "description":"",
      "minzoom":0,
       "maxzoom":14,
       "fields":{}
     }],
"tiles":["http://10.10.0.12:9001/{z}/{x}/{y}.pbf"],"tilejson":"2.0.0"}

[e-n-f]

As far as I know there's no way to represent a null value in the vector tile format, so that's why it doesn't include the null property for the features that have "gloei": null.

I am surprised, though, that you are not seeing it as a Number in the tilejson for the features that do have no-null values. I just tried

{ "type": "Feature", "properties": { "gloei": 3 }, "geometry": { "type": "Point", "coordinates": [ -122, 37 ]} }
{ "type": "Feature", "properties": { "gloei": null }, "geometry": { "type": "Point", "coordinates": [ -121, 37 ]} }

with

tippecanoe -f -o nullprop.mbtiles nullprop.json

and got the expected metadata:

$ sqlite3 nullprop.mbtiles
SQLite version 3.8.5 2014-08-15 22:37:57
Enter ".help" for usage hints.
sqlite> select * from metadata;
name|nullprop.mbtiles
description|nullprop.mbtiles
version|1
minzoom|0
maxzoom|14
center|-122.000000,37.000000,14
bounds|-122.000000,37.000000,-121.000000,37.000000
type|overlay
format|pbf
json|{"vector_layers": [ { "id": "nullprop", "description": "", "minzoom": 0, "maxzoom": 14, "fields": {"gloei": "Number"} } ] }

with gloei declared as a Number in the json. Do you have a sample of your GeoJSON input that demonstrates the problem?

[stvno]

The whole GeoJSON file is 2.8GB which is a bit big to attach here, but I created a new GeoJSON from the first few features and annoyingly that one works fine; it does show all the properties. I'll try some more to see if I can create a small but failing geojson.

[stvno]

After working my way through the large geojson I realised something went wrong with the export and all gloei values where null. I redid the export and now the gloei properties show up, so it was a mistake on my side and this issue can be closed.

[e-n-f]

Great! Glad it is working for you now.

[clouddie]

@ericfischer Hi, just got caught by this as well, null properties are dropped (silently), non-null properties are kept. I understand this is the accepted behaviour.

For information, the library geojson-vt has a different behaviour : the null properties are kept and transformed to string "null"

[e-n-f]

Oh, thanks for pointing that out, @clouddie! I think Tippecanoe is following Mapnik's behavior with null properties, but it's good to know that geojson-vt is doing something different, so we can figure out what the right thing is to do and make everything behave the same.

[springmeyer]

Correct, the spec does not currently keep null values, by design. This is being discussed at mapbox/vector-tile-spec#62.