provider/postgis: no error thrown when geoFieldname is missing

provider/postgis/error.go

@@ -21,3 +21,12 @@ type ErrUnclosedToken string
 func (e ErrUnclosedToken) Error() string {
 	return fmt.Sprintf("postgis: unclosed token in (%v)", string(e))
 }
+
+type ErrGeomFieldNotFound struct {
+	GeomFieldName string
+	LayerName     string
+}
+
+func (e ErrGeomFieldNotFound) Error() string {
+	return fmt.Sprintf("postgis: geom fieldname (%v) not found for layer (%v)", e.GeomFieldName, e.LayerName)
+}

provider/postgis/postgis.go

@@ -539,6 +539,21 @@ func (p Provider) TileFeatures(ctx context.Context, layer string, tile provider.
 	// fetch rows FieldDescriptions. this gives us the OID for the data types returned to aid in decoding
 	fdescs := rows.FieldDescriptions()
 
+	// loop our field descriptions looking for the geometry field
+	var geomFieldFound bool
+	for i := range fdescs {
+		if fdescs[i].Name == plyr.GeomFieldName() {
+			geomFieldFound = true
+			break
+		}
+	}
+	if !geomFieldFound {
+		return ErrGeomFieldNotFound{
+			GeomFieldName: plyr.GeomFieldName(),
+			LayerName:     plyr.Name(),
+		}
+	}
+
 	for rows.Next() {
 		// context check
 		if err := ctx.Err(); err != nil {

provider/postgis/postgis_test.go

@@ -225,6 +225,7 @@ func TestTileFeatures(t *testing.T) {
 	type tcase struct {
 		layerConfig          map[string]interface{}
 		tile                 *slippy.Tile
+		expectedErr          error
 		expectedFeatureCount int
 		expectedTags         []string
 	}
@@ -268,8 +269,8 @@ func TestTileFeatures(t *testing.T) {
 
 			return nil
 		})
-		if err != nil {
-			t.Errorf("unexpected err: %v", err)
+		if err != tc.expectedErr {
+			t.Errorf("expected err (%v) got err (%v)", tc.expectedErr, err)
 			return
 		}
 
@@ -439,12 +440,24 @@ func TestTileFeatures(t *testing.T) {
 				postgis.ConfigKeyGeomIDField: "id",
 				postgis.ConfigKeyGeomField:   "geometry",
 				// this SQL is a workaround the normal !BBOX! WHERE clause. we're simulating a null geometry lookup in the table and don't want to filter by bounding box
-				postgis.ConfigKeySQL: "SELECT id, ST_AsBinary(geometry) AS geometry, !BBOX! as bbox FROM null_geom_test",
+				postgis.ConfigKeySQL: "SELECT id, ST_AsBinary(geometry) AS geometry, !BBOX! AS bbox FROM null_geom_test",
 			},
 			tile:                 slippy.NewTile(16, 11241, 26168, 64, tegola.WebMercator),
 			expectedFeatureCount: 1,
 			expectedTags:         []string{"bbox"},
 		},
+		"missing geom field name": {
+			layerConfig: map[string]interface{}{
+				postgis.ConfigKeyLayerName: "missing_geom_field_name",
+				postgis.ConfigKeyGeomField: "geom",
+				postgis.ConfigKeySQL:       "SELECT ST_AsBinary(geom) FROM three_d_test WHERE geom && !BBOX!",
+			},
+			tile: slippy.NewTile(16, 11241, 26168, 64, tegola.WebMercator),
+			expectedErr: postgis.ErrGeomFieldNotFound{
+				GeomFieldName: "geom",
+				LayerName:     "missing_geom_field_name",
+			},
+		},
 	}
 
 	for name, tc := range tests {

provider/postgis/util.go

@@ -189,8 +189,10 @@ func transformVal(valType pgtype.OID, val interface{}) (interface{}, error) {
 	}
 }
 
-func decipherFields(ctx context.Context, geoFieldname, idFieldname string, descriptions []pgx.FieldDescription, values []interface{}) (gid uint64, geom []byte, tags map[string]interface{}, err error) {
+// decipherFields is responsible for processing the SQL result set, decoding geometries, ids and feature tags.
+func decipherFields(ctx context.Context, geomFieldname, idFieldname string, descriptions []pgx.FieldDescription, values []interface{}) (gid uint64, geom []byte, tags map[string]interface{}, err error) {
 	var ok bool
+
 	tags = make(map[string]interface{})
 
 	for i := range values {
@@ -207,9 +209,9 @@ func decipherFields(ctx context.Context, geoFieldname, idFieldname string, descr
 		desc := descriptions[i]
 
 		switch desc.Name {
-		case geoFieldname:
+		case geomFieldname:
 			if geom, ok = values[i].([]byte); !ok {
-				return 0, nil, nil, fmt.Errorf("unable to convert geometry field (%v) into bytes.", geoFieldname)
+				return 0, nil, nil, fmt.Errorf("unable to convert geometry field (%v) into bytes.", geomFieldname)
 			}
 		case idFieldname:
 			gid, err = gId(values[i])
@@ -238,7 +240,7 @@ func decipherFields(ctx context.Context, geoFieldname, idFieldname string, descr
 		}
 	}
 
-	return gid, geom, tags, err
+	return gid, geom, tags, nil
 }
 
 func gId(v interface{}) (gid uint64, err error) {