geojson: null json into non-pointer Feature/FeatureCollection will set them to empty

Author: paulmach

Diff for: geojson/feature.go

@@ -1,6 +1,7 @@
 package geojson
 
 import (
+	"bytes"
 	"fmt"
 
 	"github.com/paulmach/orb"
@@ -79,6 +80,11 @@ func UnmarshalFeature(data []byte) (*Feature, error) {
 // UnmarshalJSON handles the correct unmarshalling of the data
 // into the orb.Geometry types.
 func (f *Feature) UnmarshalJSON(data []byte) error {
+	if bytes.Equal(data, []byte(`null`)) {
+		*f = Feature{}
+		return nil
+	}
+
 	doc := &featureDoc{}
 	err := unmarshalJSON(data, &doc)
 	if err != nil {

Diff for: geojson/feature_collection.go

@@ -7,6 +7,7 @@ json.Unmarshaler interfaces as well as helper functions such as
 package geojson
 
 import (
+	"bytes"
 	"fmt"
 
 	"go.mongodb.org/mongo-driver/bson"
@@ -85,6 +86,11 @@ func newFeatureCollectionDoc(fc FeatureCollection) map[string]interface{} {
 // UnmarshalJSON decodes the data into a GeoJSON feature collection.
 // Extra/foreign members will be put into the `ExtraMembers` attribute.
 func (fc *FeatureCollection) UnmarshalJSON(data []byte) error {
+	if bytes.Equal(data, []byte(`null`)) {
+		*fc = FeatureCollection{}
+		return nil
+	}
+
 	tmp := make(map[string]nocopyRawMessage, 4)
 
 	err := unmarshalJSON(data, &tmp)

Diff for: geojson/feature_collection_test.go

@@ -185,6 +185,40 @@ func TestFeatureCollectionMarshalJSON(t *testing.T) {
 	}
 }
 
+func TestFeatureCollectionMarshalJSON_null(t *testing.T) {
+	t.Run("pointer", func(t *testing.T) {
+		type S struct {
+			GeoJSON *FeatureCollection `json:"geojson"`
+		}
+
+		var s S
+		err := json.Unmarshal([]byte(`{"geojson": null}`), &s)
+		if err != nil {
+			t.Fatalf("unmarshal error: %v", err)
+		}
+
+		if s.GeoJSON != nil {
+			t.Errorf("should be nil, got: %v", s)
+		}
+	})
+
+	t.Run("non-pointer", func(t *testing.T) {
+		type S struct {
+			GeoJSON FeatureCollection `json:"geojson"`
+		}
+
+		var s S
+		err := json.Unmarshal([]byte(`{"geojson": null}`), &s)
+		if err != nil {
+			t.Fatalf("unmarshal error: %v", err)
+		}
+
+		if !reflect.DeepEqual(s.GeoJSON, FeatureCollection{}) {
+			t.Errorf("should be empty, got: %v", s)
+		}
+	})
+}
+
 func TestFeatureCollectionMarshal(t *testing.T) {
 	fc := NewFeatureCollection()
 	fc.Features = nil

Diff for: geojson/feature_test.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"encoding/json"
 	"io/ioutil"
+	"reflect"
 	"strings"
 	"testing"
 
@@ -201,6 +202,40 @@ func TestUnmarshalFeature_missingGeometry(t *testing.T) {
 	})
 }
 
+func TestFeatureMarshalJSON_null(t *testing.T) {
+	t.Run("pointer", func(t *testing.T) {
+		type S struct {
+			GeoJSON *Feature `json:"geojson"`
+		}
+
+		var s S
+		err := json.Unmarshal([]byte(`{"geojson": null}`), &s)
+		if err != nil {
+			t.Fatalf("unmarshal error: %v", err)
+		}
+
+		if s.GeoJSON != nil {
+			t.Errorf("should be nil, got: %v", s)
+		}
+	})
+
+	t.Run("non-pointer", func(t *testing.T) {
+		type S struct {
+			GeoJSON Feature `json:"geojson"`
+		}
+
+		var s S
+		err := json.Unmarshal([]byte(`{"geojson": null}`), &s)
+		if err != nil {
+			t.Fatalf("unmarshal error: %v", err)
+		}
+
+		if !reflect.DeepEqual(s.GeoJSON, Feature{}) {
+			t.Errorf("should be empty, got: %v", s)
+		}
+	})
+}
+
 func TestUnmarshalBSON_missingGeometry(t *testing.T) {
 	t.Run("missing geometry", func(t *testing.T) {
 		f := NewFeature(nil)

Diff for: geojson/geometry_test.go

@@ -237,6 +237,40 @@ func TestGeometryUnmarshal_errors(t *testing.T) {
 	}
 }
 
+func TestGeometryMarshalJSON_null(t *testing.T) {
+	t.Run("pointer", func(t *testing.T) {
+		type S struct {
+			GeoJSON *Geometry `json:"geojson"`
+		}
+
+		var s S
+		err := json.Unmarshal([]byte(`{"geojson": null}`), &s)
+		if err != nil {
+			t.Fatalf("unmarshal error: %v", err)
+		}
+
+		if s.GeoJSON != nil {
+			t.Errorf("should be nil, got: %v", s)
+		}
+	})
+
+	t.Run("feature with null geometry", func(t *testing.T) {
+		type S struct {
+			GeoJSON *Feature `json:"geojson"`
+		}
+
+		var s S
+		err := json.Unmarshal([]byte(`{"geojson": {"type":"Feature","geometry":null,"properties":null}}`), &s)
+		if err != nil {
+			t.Fatalf("unmarshal error: %v", err)
+		}
+
+		if s.GeoJSON.Geometry != nil {
+			t.Errorf("should be nil, got: %v", s)
+		}
+	})
+}
+
 func TestHelperTypes(t *testing.T) {
 	// This test makes sure the marshal-unmarshal loop does the same thing.
 	// The code and types here are complicated to avoid duplicate code.