structs: add omitempty support to Values()

structs.go

@@ -112,10 +112,16 @@ func (s *Struct) Map() map[string]interface{} {
 // A value with the option of "omitnested" stops iterating further if the type
 // is a struct. Example:
 //
-//   // Field is not processed further by this package.
+//   // Fields is not processed further by this package.
-//   Field time.Time     `structs:"myName,omitnested"`
+//   Field time.Time     `structs:",omitnested"`
 //   Field *http.Request `structs:",omitnested"`
 //
+// A tag value with the option of "omitempty" ignores that particular field and
+// is not added to the values if the field value is empty. Example:
+//
+//   // Field is skipped if empty
+//   Field string `structs:",omitempty"`
+//
 // Note that only exported fields of a struct can be accessed, non exported
 // fields  will be neglected.
 func (s *Struct) Values() []interface{} {
@@ -128,6 +134,17 @@ func (s *Struct) Values() []interface{} {
 
 		_, tagOpts := parseTag(field.Tag.Get(DefaultTagName))
 
+		// if the value is a zero value and the field is marked as omitempty do
+		// not include
+		if tagOpts.Has("omitempty") {
+			zero := reflect.Zero(val.Type()).Interface()
+			current := val.Interface()
+
+			if reflect.DeepEqual(current, zero) {
+				continue
+			}
+		}
+
 		if IsStruct(val.Interface()) && !tagOpts.Has("omitnested") {
 			// look out for embedded structs, and convert them to a
 			// []interface{} to be added to the final values slice
@@ -182,7 +199,7 @@ func getFields(v reflect.Value) []*Field {
 }
 
 // Field returns a new Field struct that provides several high level functions
-// around a single struct field entitiy. It panics if the field is not found.
+// around a single struct field entity. It panics if the field is not found.
 func (s *Struct) Field(name string) *Field {
 	f, ok := s.FieldOk(name)
 	if !ok {
@@ -193,7 +210,7 @@ func (s *Struct) Field(name string) *Field {
 }
 
 // Field returns a new Field struct that provides several high level functions
-// around a single struct field entitiy. The boolean returns true if the field
+// around a single struct field entity. The boolean returns true if the field
 // was found.
 func (s *Struct) FieldOk(name string) (*Field, bool) {
 	t := s.value.Type()

structs_test.go

@@ -301,6 +301,24 @@ func TestValues(t *testing.T) {
 	}
 }
 
+func TestValues_OmitEmpty(t *testing.T) {
+	type A struct {
+		Name  string
+		Value int `structs:",omitempty"`
+	}
+
+	a := A{Name: "example"}
+	s := Values(a)
+
+	if len(s) != 1 {
+		t.Errorf("Values of omitted empty fields should be not counted")
+	}
+
+	if s[0].(string) != "example" {
+		t.Errorf("Values of omitted empty fields should left the value example")
+	}
+}
+
 func TestValues_OmitNested(t *testing.T) {
 	type A struct {
 		Name  string