structure: add omitnested support to Fields

structure.go

@@ -88,6 +88,37 @@ func Values(s interface{}) []interface{} {
 
 }
 
+// Fields returns a slice of field names. A struct tag with the content of "-"
+// ignores the checking of that particular field. Example:
+//
+//   // Field is ignored by this package.
+//   Field bool `structure:"-"`
+//
+// Note that only exported fields of a struct can be accessed, non exported
+// fields  will be neglected. It panics if s's kind is not struct.
+func Fields(s interface{}) []string {
+	v, fields := strctInfo(s)
+
+	keys := make([]string, 0)
+	for _, field := range fields {
+		val := v.FieldByName(field.Name)
+
+		_, tagOpts := parseTag(field.Tag.Get(DefaultTagName))
+
+		if IsStruct(val.Interface()) && !tagOpts.Has("omitnested") {
+			// look out for embedded structs, and convert them to a
+			// []string to be added to the final values slice
+			for _, embeddedVal := range Fields(val.Interface()) {
+				keys = append(keys, embeddedVal)
+			}
+		}
+
+		keys = append(keys, field.Name)
+	}
+
+	return keys
+}
+
 // IsZero returns true if all fields in a struct is a zero value (not
 // initialized) A struct tag with the content of "-" ignores the checking of
 // that particular field. Example:
@@ -163,34 +194,6 @@ func HasZero(s interface{}) bool {
 	return false
 }
 
-// Fields returns a slice of field names. A struct tag with the content of "-"
-// ignores the checking of that particular field. Example:
-//
-//   // Field is ignored by this package.
-//   Field bool `structure:"-"`
-//
-// Note that only exported fields of a struct can be accessed, non exported
-// fields  will be neglected. It panics if s's kind is not struct.
-func Fields(s interface{}) []string {
-	v, fields := strctInfo(s)
-
-	keys := make([]string, 0)
-	for _, field := range fields {
-		val := v.FieldByName(field.Name)
-		if IsStruct(val.Interface()) {
-			// look out for embedded structs, and convert them to a
-			// []string to be added to the final values slice
-			for _, embeddedVal := range Fields(val.Interface()) {
-				keys = append(keys, embeddedVal)
-			}
-		}
-
-		keys = append(keys, field.Name)
-	}
-
-	return keys
-}
-
 // IsStruct returns true if the given variable is a struct or a pointer to
 // struct.
 func IsStruct(s interface{}) bool {

structure_test.go

@@ -411,6 +411,43 @@ func TestFields(t *testing.T) {
 	}
 }
 
+func TestFields_OmitNested(t *testing.T) {
+	type A struct {
+		Name    string
+		Value   string
+		Number  int
+		Enabled bool
+	}
+	a := A{Name: "example"}
+
+	type B struct {
+		A A `structure:",omitnested"`
+		C int
+	}
+	b := &B{A: a, C: 123}
+
+	s := Fields(b)
+
+	if len(s) != 2 {
+		t.Errorf("Fields should omit nested struct. Expecting 2 got: %d", len(s))
+	}
+
+	inSlice := func(val interface{}) bool {
+		for _, v := range s {
+			if reflect.DeepEqual(v, val) {
+				return true
+			}
+		}
+		return false
+	}
+
+	for _, val := range []interface{}{"A", "C"} {
+		if !inSlice(val) {
+			t.Errorf("Fields should have the value %v", val)
+		}
+	}
+}
+
 func TestFields_Nested(t *testing.T) {
 	type A struct {
 		Name string