From 6cb27c68f607ac54702ca4069d0722fe264cb849 Mon Sep 17 00:00:00 2001
From: viatoriche / Maxim Panfilov <Maxim.Panfilov@acronis.com>
Date: Mon, 9 Sep 2019 18:04:34 +0300
Subject: [PATCH] add support for pointers fields

---
 decode.go      | 10 ++++++++++
 decode_test.go | 13 ++++++++++++-
 encode.go      | 24 ++++++++++++++++++------
 encode_test.go | 12 +++++++++++-
 4 files changed, 51 insertions(+), 8 deletions(-)

diff --git a/decode.go b/decode.go
index f4f9130..ae04ff2 100644
--- a/decode.go
+++ b/decode.go
@@ -109,6 +109,16 @@ func (d *decoder) coerce(query string, target reflect.Kind, field reflect.Value)
 	var err error
 	var c interface{}
 
+	if target == reflect.Ptr {
+		elemType := field.Type().Elem()
+		k := elemType.Kind()
+		if field.IsNil() {
+			field.Set(reflect.New(elemType))
+		}
+		elem := field.Elem()
+		return d.coerce(query, k, elem)
+	}
+
 	switch target {
 	case reflect.String:
 		field.SetString(query)
diff --git a/decode_test.go b/decode_test.go
index 1c8b04e..920fb96 100644
--- a/decode_test.go
+++ b/decode_test.go
@@ -49,7 +49,9 @@ type TestStruct struct {
 	Float32s []float32
 	Float64s []float64
 	hidden   int
-	Hidden   int `qstring:"-"`
+	Hidden   int       `qstring:"-"`
+	PtrInt   *int      `qstring:"ptrInt"`
+	PtrNil   *struct{} `qstring:"ptrNil"`
 }
 
 func TestUnmarshall(t *testing.T) {
@@ -83,6 +85,7 @@ func TestUnmarshall(t *testing.T) {
 		"ubigs":    []string{"12", "13", "14"},
 		"float32s": []string{"6000", "6001", "6002"},
 		"float64s": []string{"7000", "7001", "7002"},
+		"ptrInt":   []string{"10"},
 	}
 
 	err := Unmarshal(query, &ts)
@@ -97,6 +100,14 @@ func TestUnmarshall(t *testing.T) {
 	if len(ts.Fields) != 2 {
 		t.Errorf("Expected 2 fields, got %d", len(ts.Fields))
 	}
+
+	if *ts.PtrInt != 10 {
+		t.Errorf("Wrong PtrInt value: %v", ts.PtrInt)
+	}
+
+	if ts.PtrNil != nil {
+		t.Errorf("Wrong PtrNil value: %v", ts.PtrNil)
+	}
 }
 
 func TestUnmarshalNested(t *testing.T) {
diff --git a/encode.go b/encode.go
index 9bc437a..d151239 100644
--- a/encode.go
+++ b/encode.go
@@ -73,14 +73,14 @@ func (e *encoder) marshal() (url.Values, error) {
 
 func (e *encoder) value(val reflect.Value) (url.Values, error) {
 	elem := val.Elem()
-	typ := elem.Type()
+	elemType := elem.Type()
 
 	var err error
 	var output = make(url.Values)
 	for i := 0; i < elem.NumField(); i++ {
 		// pull out the qstring struct tag
 		elemField := elem.Field(i)
-		typField := typ.Field(i)
+		typField := elemType.Field(i)
 		qstring, omit := parseTag(typField.Tag.Get(Tag))
 		if qstring == "" {
 			// resolvable fields must have at least the `flag` struct tag
@@ -93,16 +93,28 @@ func (e *encoder) value(val reflect.Value) (url.Values, error) {
 			continue
 		}
 
+		var typFieldCheck reflect.Type
+
+		if typField.Type.Kind() == reflect.Ptr {
+			typFieldCheck = typField.Type.Elem()
+			if elemField.IsNil() {
+				continue
+			}
+			elemField = elemField.Elem()
+		} else {
+			typFieldCheck = typField.Type
+		}
+
 		// only do work if the current fields query string parameter was provided
-		switch k := typField.Type.Kind(); k {
+		switch k := typFieldCheck.Kind(); k {
 		default:
 			output.Set(qstring, marshalValue(elemField, k))
 		case reflect.Slice:
 			output[qstring] = marshalSlice(elemField)
-		case reflect.Ptr:
-			marshalStruct(output, qstring, reflect.Indirect(elemField), k)
 		case reflect.Struct:
-			marshalStruct(output, qstring, elemField, k)
+			if err := marshalStruct(output, qstring, elemField, k); err != nil {
+				return nil, err
+			}
 		}
 	}
 	return output, err
diff --git a/encode_test.go b/encode_test.go
index cd12cd5..16b8e10 100644
--- a/encode_test.go
+++ b/encode_test.go
@@ -8,6 +8,7 @@ import (
 )
 
 func TestMarshallString(t *testing.T) {
+	i := 10
 	ts := TestStruct{
 		Name:     "SomeName",
 		Do:       true,
@@ -37,6 +38,8 @@ func TestMarshallString(t *testing.T) {
 		UBigs:    []uint64{12, 13},
 		Float32s: []float32{6000, 6001},
 		Float64s: []float64{7000, 7001},
+		PtrInt:   &i,
+		PtrNil:   nil,
 	}
 
 	expected := []string{"name=SomeName", "do=true", "page=1", "id=12", "small=13",
@@ -46,7 +49,7 @@ func TestMarshallString(t *testing.T) {
 		"smalls=7", "meds=9", "meds=10", "bigs=12", "bigs=13", "upages=2",
 		"upages=3", "uids=5", "uids=6", "usmalls=8", "usmalls=9", "umeds=9",
 		"umeds=10", "ubigs=12", "ubigs=13", "float32s=6000", "float32s=6001",
-		"float64s=7000", "float64s=7001"}
+		"float64s=7000", "float64s=7001", "ptrInt=10"}
 	query, err := MarshalString(&ts)
 	if err != nil {
 		t.Fatal(err.Error())
@@ -60,6 +63,7 @@ func TestMarshallString(t *testing.T) {
 }
 
 func TestMarshallValues(t *testing.T) {
+	i := 10
 	ts := TestStruct{
 		Name:     "SomeName",
 		Do:       true,
@@ -89,6 +93,8 @@ func TestMarshallValues(t *testing.T) {
 		UBigs:    []uint64{12, 13},
 		Float32s: []float32{6000, 6001},
 		Float64s: []float64{7000, 7001},
+		PtrInt:   &i,
+		PtrNil:   nil,
 	}
 
 	expected := url.Values{
@@ -120,6 +126,7 @@ func TestMarshallValues(t *testing.T) {
 		"ubigs":    []string{"12", "13", "14"},
 		"float32s": []string{"6000", "6001", "6002"},
 		"float64s": []string{"7000", "7001", "7002"},
+		"ptrInt":   []string{"10"},
 	}
 	values, err := Marshal(&ts)
 	if err != nil {
@@ -130,6 +137,9 @@ func TestMarshallValues(t *testing.T) {
 		t.Errorf("Expected %d fields, got %d. Hidden is %q",
 			len(expected), len(values), values["hidden"])
 	}
+	if values["ptrInt"][0] != expected["ptrInt"][0] {
+		t.Errorf("Wrong ptrInt value: %v", values["ptrInt"][0])
+	}
 }
 
 func TestInvalidMarshalString(t *testing.T) {