topojson/topojson-client

topojson.feature of a FeatureCollection of MultiPolygons returns a "Feature" object with null as geometry property

Closed this issue · 4 comments

MathiasVersichele commented

I have the topojson file in attachment:
topojson_issue.json.txt

which I made with the "pytopojson" library. I'm pretty confident it looks ok, library doesn't complain but I guess there isn't an online validator. Geojson-wise it's a feature collection of 20 multipolygons. I use the following snippet in javascript:

d3.json("https://75.119.131.164/data/hourly_homezones.json", function(error, topology) {
    console.log(topojson.feature(topology, topology.objects.my_geojson.geometries));
};

which returns:

image

I don't think this is an expected response. I expect a featurecollection of multipolygons.

Any foolish mistake I'm making ? Or is this a bug ?

mbostock commented

What happens if you do this?

topojson.feature(topology, topology.objects.my_geojson)
MathiasVersichele commented

Uncaught TypeError: Cannot read properties of undefined (reading 'objects') at Object.<anonymous> (coverage.html:69:53) at Object.t (d3.v3.min.js:1:1565) at XMLHttpRequest.i (d3.v3.min.js:1:10120)

thrown at the console.log line

mbostock commented

Cannot read properties of undefined (reading 'objects')

This means that topology is undefined, which means it’s not even calling topojson.feature, so there must be a bug elsewhere.

I can’t reproduce this.

https://observablehq.com/d/e78f899d7a22df38

MathiasVersichele commented

I kept trying and trying, finally works, don't really know why it didn't before. Not a bug indeed. Thx for investigating @mbostock !