From 5740d112407fdbe77c133a4d4f7f589888b3ed30 Mon Sep 17 00:00:00 2001
From: what <what-00@qq.com>
Date: Wed, 21 Jun 2023 13:12:09 +0800
Subject: [PATCH] =?UTF-8?q?[fix]=20=E4=BF=AE=E5=A4=8D=20converting=20NULL?=
 =?UTF-8?q?=20to=20string=20is=20unsupported=20=E9=94=99=E8=AF=AF?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 scan.go      | 47 ++++++++++++++++++++++++++---------------------
 scan_test.go |  2 +-
 2 files changed, 27 insertions(+), 22 deletions(-)

diff --git a/scan.go b/scan.go
index e963f8e..c78077b 100644
--- a/scan.go
+++ b/scan.go
@@ -4,7 +4,6 @@ import (
 	"database/sql"
 	"encoding/json"
 	"errors"
-	"fmt"
 	"reflect"
 )
 
@@ -115,6 +114,9 @@ func sStructSlice(rows *sql.Rows, dest any) (result RowScan) {
 				case reflect.Slice, reflect.Struct, reflect.Map:
 					scanArgs[i] = &[]uint8{}
 					jFields[i] = v.Field(f)
+				case reflect.String:
+					scanArgs[i] = &sql.NullString{}
+					jFields[i] = v.Field(f)
 				default:
 					scanArgs[i] = v.Field(f).Addr().Interface()
 				}
@@ -129,15 +131,16 @@ func sStructSlice(rows *sql.Rows, dest any) (result RowScan) {
 
 		// json 字符串 反序列化
 		for i, rv := range jFields {
-			v := rv.Addr().Interface()
-			data := *scanArgs[i].(*[]uint8)
-
-			if len(data) == 0 {
-				continue
-			}
-
-			if err := json.Unmarshal(data, &v); err != nil {
-				panic(err)
+			switch rv.Kind() {
+			case reflect.String:
+				rv.SetString(scanArgs[i].(*sql.NullString).String)
+			default:
+				if data := *scanArgs[i].(*[]uint8); len(data) > 0 {
+					v := rv.Addr().Interface()
+					if err := json.Unmarshal(data, &v); err != nil {
+						panic(err)
+					}
+				}
 			}
 		}
 
@@ -185,8 +188,9 @@ func sStruct(rows *sql.Rows, dest any) (result RowScan) {
 					case reflect.Slice, reflect.Struct, reflect.Map:
 						scanArgs[i] = &[]uint8{}
 						jFields[i] = v.Field(f)
-
-						fmt.Printf("123 %+#v \n", v.Field(f))
+					case reflect.String:
+						scanArgs[i] = &sql.NullString{}
+						jFields[i] = v.Field(f)
 					default:
 						scanArgs[i] = v.Field(f).Addr().Interface()
 					}
@@ -201,15 +205,16 @@ func sStruct(rows *sql.Rows, dest any) (result RowScan) {
 
 			// json 字符串 反序列化
 			for i, rv := range jFields {
-				v := rv.Addr().Interface()
-				data := *scanArgs[i].(*[]uint8)
-
-				if len(data) == 0 {
-					continue
-				}
-
-				if err := json.Unmarshal(data, &v); err != nil {
-					panic(err)
+				switch rv.Kind() {
+				case reflect.String:
+					rv.SetString(scanArgs[i].(*sql.NullString).String)
+				default:
+					if data := *scanArgs[i].(*[]uint8); len(data) > 0 {
+						v := rv.Addr().Interface()
+						if err := json.Unmarshal(data, &v); err != nil {
+							panic(err)
+						}
+					}
 				}
 			}
 
diff --git a/scan_test.go b/scan_test.go
index 1d0233b..50c9f2b 100644
--- a/scan_test.go
+++ b/scan_test.go
@@ -70,7 +70,7 @@ func TestScanJsonFieldStruct(t *testing.T) {
 		Arr  []int64        `db:"arr"`
 	}{}
 
-	myConn.Select(`select 0 as id, 'test' as code, '{"a":1}' as map, '[3, 4]' as arr`, []any{}, &dest)
+	myConn.Select(`select 0 as id, NULL as code, '{"a":1}' as map, '[3, 4]' as arr`, []any{}, &dest)
 
 	t.Log(dest)
 }