for empty slices no header is exported

Author: sauterp

flatstruct.go

@@ -58,27 +58,30 @@ func CompNRowsCols(s interface{}) (nrows, ncols int) {
 
 // FlattenSlice TODO
 func FlattenSlice(headerBase string, s interface{}) (headers []string, rows [][]string, err error) {
-	headers = append(headers, headerBase)
-
 	sValue := reflect.ValueOf(s)
-	var newHeaders []string
-	for i := 0; i < sValue.Len(); i++ {
-		var newRows [][]string
-		var err error
-		newHeaders, newRows, err = FlattenBegin(headerBase, sValue.Index(i).Interface())
-		if err != nil {
-			// TODO
-		}
-		iJSON, err := json.Marshal(i)
-		if err != nil {
-			// TODO
-		}
-		for r := 0; r < len(newRows); r++ {
-			newRows[r] = append([]string{string(iJSON)}, newRows[r]...)
+
+	if sValue.Len() > 0 {
+		headers = append(headers, headerBase)
+		var newHeaders []string
+		for i := 0; i < sValue.Len(); i++ {
+			var newRows [][]string
+			var err error
+			newHeaders, newRows, err = FlattenBegin(headerBase, sValue.Index(i).Interface())
+			if err != nil {
+				// TODO
+			}
+			iJSON, err := json.Marshal(i)
+			if err != nil {
+				// TODO
+			}
+			for r := 0; r < len(newRows); r++ {
+				newRows[r] = append([]string{string(iJSON)}, newRows[r]...)
+			}
+			rows = append(rows, newRows...)
 		}
-		rows = append(rows, newRows...)
+		headers = append(headers, newHeaders...)
 	}
-	headers = append(headers, newHeaders...)
+
 	return headers, rows, nil
 }
 

flatstruct_test.go

@@ -87,6 +87,23 @@ func TestFlatStruct(t *testing.T) {
 	flatUnflatTest(t, structured, flattened, headerBase, "Flatten flat stuct value", "Should be flattened flat struct value", "Flatten flat stuct value", "Should be unflattened flat struct value")
 }
 
+func TestStructWithEmptySlice(t *testing.T) {
+	type WithEmptySlice struct {
+		A          string `json:"a"`
+		EmptySlice []int  `json:"empty_slice"`
+	}
+	structured := WithEmptySlice{
+		A:          "aval",
+		EmptySlice: nil,
+	}
+	flattened := [][]string{
+		{"myBase.a"},
+		{`"aval"`},
+	}
+	headerBase := "myBase"
+	flatUnflatTest(t, structured, flattened, headerBase, "Flatten stuct value with emtpy slice", "Should be flattened struct value with emtpy slice", "Flatten stuct value with emtpy slice", "Should be unflattened struct value with emtpy slice")
+}
+
 func TestNestedStruct(t *testing.T) {
 	type ABCD struct {
 		AB AB     `json:"ab"`