Resolves felt/geo#193

lib/geo/json/decoder.ex

@@ -197,7 +197,19 @@ defmodule Geo.JSON.Decoder do
   defp do_decode("Feature", nil, _properties, _id), do: nil
 
   defp do_decode("Feature", geometry, properties, _id) do
-    do_decode(Map.get(geometry, "type"), Map.get(geometry, "coordinates"), properties, nil)
+    cond do
+
+      Map.get(geometry, "type") == "GeometryCollection" ->
+        geometry_collection = decode!(geometry)
+
+        %GeometryCollection{
+          geometries: geometry_collection.geometries,
+          properties: properties
+        }
+
+      true ->
+        do_decode(Map.get(geometry, "type"), Map.get(geometry, "coordinates"), properties, nil)
+    end
   end
 
   defp do_decode(type, [x, y, _z], properties, crs) do

test/geo/json_test.exs

@@ -473,4 +473,57 @@ defmodule Geo.JSON.Test do
 
     assert(Geo.JSON.encode!(gc, feature: true) == expected)
   end
+
+  test "Decode Feature with GeometryCollection geometry" do
+    # Similar to response from https://api.weather.gov/zones/county/FLC017
+    json = """
+    {
+      "@context": {
+          "@version": "1.1"
+      },
+      "id": "https://api.weather.gov/zones/county/FLC017",
+      "type": "Feature",
+      "geometry": {
+          "type": "GeometryCollection",
+          "geometries": [
+              {
+                  "type": "MultiPolygon",
+                  "coordinates": [[[[102.0, 2.0], [103.0, 2.0], [103.0, 3.0], [102.0, 3.0], [102.0, 2.0]]],[[[100.0, 0.0], [101.0, 0.0], [101.0, 1.0], [100.0, 1.0], [100.0, 0.0]],[[100.2, 0.2], [100.8, 0.2], [100.8, 0.8], [100.2, 0.8], [100.2, 0.2]]]]
+              },
+              {
+                  "type": "MultiPolygon",
+                  "coordinates": [[[[102.0, 2.0], [103.0, 2.0], [103.0, 3.0], [102.0, 3.0], [102.0, 2.0]]],[[[100.0, 0.0], [101.0, 0.0], [101.0, 1.0], [100.0, 1.0], [100.0, 0.0]],[[100.2, 0.2], [100.8, 0.2], [100.8, 0.8], [100.2, 0.8], [100.2, 0.2]]]]
+              }
+          ]
+      },
+      "properties": {
+          "@id": "https://api.weather.gov/zones/county/FLC017",
+          "@type": "wx:Zone",
+          "id": "FLC017",
+          "type": "county",
+          "name": "Citrus",
+          "effectiveDate": "2023-09-19T18:00:00+00:00",
+          "expirationDate": "2200-01-01T00:00:00+00:00",
+          "state": "FL",
+          "cwa": [
+              "TBW"
+          ],
+          "forecastOffices": [
+              "https://api.weather.gov/offices/TBW"
+          ],
+          "timeZone": [
+              "America/New_York"
+          ],
+          "observationStations": [],
+          "radarStation": null
+      }
+    }
+    """
+
+    geom = Jason.decode!(json) |> Geo.JSON.decode!()
+
+    assert(Enum.count(geom.geometries) == 2)
+    assert(Enum.each(geom.geometries, fn (%Geo.MultiPolygon{} = g) -> true end))
+    assert geom.properties["id"] == "FLC017"
+  end
 end