Use interface argument for IAP response instead of the library defined struct

README.md

@@ -43,7 +43,8 @@ func main() {
 	req := appstore.IAPRequest{
 		ReceiptData: "your receipt data encoded by base64",
 	}
-	resp, err := client.Verify(req)
+	resp := &IAPResponse{}
+	err := client.Verify(req, resp)
 }
 ```
 

appstore/model.go

@@ -73,6 +73,10 @@ type (
 	}
 
 	// The IAPResponse type has the response properties
+	// We defined each field by the current IAP response, but some fields are not mentioned
+	// in the following Apple's document;
+	// https://developer.apple.com/library/ios/releasenotes/General/ValidateAppStoreReceipt/Chapters/ReceiptFields.html
+	// If you get other types or fileds from the IAP response, you should use the struct you defined.
 	IAPResponse struct {
 		Status            int     `json:"status"`
 		Environment       string  `json:"environment"`

appstore/validator.go

@@ -98,8 +98,7 @@ func NewWithConfig(config Config) Client {
 }
 
 // Verify sends receipts and gets validation result
-func (c *Client) Verify(req IAPRequest) (IAPResponse, error) {
+func (c *Client) Verify(req IAPRequest, result interface{}) error {
-	result := IAPResponse{}
 	_, body, errs := gorequest.New().
 		Post(c.URL).
 		Send(req).
@@ -107,10 +106,10 @@ func (c *Client) Verify(req IAPRequest) (IAPResponse, error) {
 		End()
 
 	if errs != nil {
-		return result, fmt.Errorf("%v", errs)
+		return fmt.Errorf("%v", errs)
 	}
 
-	err := json.NewDecoder(strings.NewReader(body)).Decode(&result)
+	err := json.NewDecoder(strings.NewReader(body)).Decode(result)
 
-	return result, err
+	return err
 }

appstore/validator_test.go

@@ -134,15 +134,16 @@ func TestNewWithConfigTimeout(t *testing.T) {
 func TestVerify(t *testing.T) {
 	client := New()
 
-	expected := IAPResponse{
+	expected := &IAPResponse{
 		Status: 21002,
 	}
 	req := IAPRequest{
 		ReceiptData: "dummy data",
 	}
-	actual, _ := client.Verify(req)
+	result := &IAPResponse{}
-	if !reflect.DeepEqual(actual, expected) {
+	client.Verify(req, result)
-		t.Errorf("got %v\nwant %v", actual, expected)
+	if !reflect.DeepEqual(result, expected) {
+		t.Errorf("got %v\nwant %v", result, expected)
 	}
 }
 
@@ -156,7 +157,8 @@ func TestVerifyTimeout(t *testing.T) {
 	}
 
 	expected := errors.New("")
-	_, actual := client.Verify(req)
+	result := &IAPResponse{}
+	actual := client.Verify(req, result)
 	if !reflect.DeepEqual(reflect.TypeOf(actual), reflect.TypeOf(expected)) {
 		t.Errorf("got %v\nwant %v", actual, expected)
 	}