Add option to encode value keys with '.' separators

encoder.go

@@ -11,8 +11,9 @@ type encoderFunc func(reflect.Value) string
 
 // Encoder encodes values from a struct into url.Values.
 type Encoder struct {
-	cache  *cache
-	regenc map[reflect.Type]encoderFunc
+	cache           *cache
+	regenc          map[reflect.Type]encoderFunc
+	keyOriginalPath bool
 }
 
 // NewEncoder returns a new Encoder with defaults.
@@ -26,7 +27,7 @@ func NewEncoder() *Encoder {
 func (e *Encoder) Encode(src interface{}, dst map[string][]string) error {
 	v := reflect.ValueOf(src)
 
-	return e.encode(v, dst)
+	return e.encode(v, dst, "")
 }
 
 // RegisterEncoder registers a converter for encoding a custom type.
@@ -40,6 +41,14 @@ func (e *Encoder) SetAliasTag(tag string) {
 	e.cache.tag = tag
 }
 
+// KeyOriginalPath causes the keys of nested struct fields to keep their full original
+// name consisting of each field name in its path separated with a period.
+//
+// Allows from nested struct encoded values to be decoded again using schema.Decode.
+func (e *Encoder) KeyOriginalPath(keyOriginalPath bool) {
+	e.keyOriginalPath = keyOriginalPath
+}
+
 // isValidStructPointer test if input value is a valid struct pointer.
 func isValidStructPointer(v reflect.Value) bool {
 	return v.Type().Kind() == reflect.Ptr && v.Elem().IsValid() && v.Elem().Type().Kind() == reflect.Struct
@@ -75,7 +84,7 @@ func isZero(v reflect.Value) bool {
 	return v.Interface() == z.Interface()
 }
 
-func (e *Encoder) encode(v reflect.Value, dst map[string][]string) error {
+func (e *Encoder) encode(v reflect.Value, dst map[string][]string, prefix string) error {
 	if v.Kind() == reflect.Ptr {
 		v = v.Elem()
 	}
@@ -91,10 +100,13 @@ func (e *Encoder) encode(v reflect.Value, dst map[string][]string) error {
 		if name == "-" {
 			continue
 		}
+		if prefix != "" && e.keyOriginalPath {
+			name = prefix + "." + name
+		}
 
 		// Encode struct pointer types if the field is a valid pointer and a struct.
 		if isValidStructPointer(v.Field(i)) && !e.hasCustomEncoder(v.Field(i).Type()) {
-			err := e.encode(v.Field(i).Elem(), dst)
+			err := e.encode(v.Field(i).Elem(), dst, name)
 			if err != nil {
 				errors[v.Field(i).Elem().Type().String()] = err
 			}
@@ -115,7 +127,7 @@ func (e *Encoder) encode(v reflect.Value, dst map[string][]string) error {
 		}
 
 		if v.Field(i).Type().Kind() == reflect.Struct {
-			err := e.encode(v.Field(i), dst)
+			err := e.encode(v.Field(i), dst, name)
 			if err != nil {
 				errors[v.Field(i).Type().String()] = err
 			}

encoder_test.go

@@ -523,3 +523,37 @@ func TestRegisterEncoderWithPtrType(t *testing.T) {
 	valExists(t, "DateStart", ss.DateStart.time.String(), vals)
 	valExists(t, "DateEnd", "", vals)
 }
+
+func TestEncoderKeyOriginalPath(t *testing.T) {
+	type outter struct {
+		Inner    inner
+		InnerPtr *inner
+	}
+	type nested struct {
+		Outter outter
+	}
+
+	nest := nested{
+		Outter: outter{
+			Inner: inner{
+				F12: 12,
+			},
+			InnerPtr: &inner{
+				F12: 12,
+			},
+		},
+	}
+
+	encoder := NewEncoder()
+	encoder.KeyOriginalPath(true)
+
+	vals := map[string][]string{}
+	err := encoder.Encode(nest, vals)
+
+	t.Log(vals)
+
+	noError(t, err)
+	valsLength(t, 2, vals)
+	valExists(t, "Outter.Inner.F12", "12", vals)
+	valExists(t, "Outter.InnerPtr.F12", "12", vals)
+}