[fix] 修复 converting NULL to string is unsupported 错误

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()
 				}
@@ -129,17 +131,18 @@ func sStructSlice(rows *sql.Rows, dest any) (result RowScan) {
 
 		// json 字符串 反序列化
 		for i, rv := range jFields {
+			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()
-			data := *scanArgs[i].(*[]uint8)
-
-			if len(data) == 0 {
-				continue
-			}
-
 					if err := json.Unmarshal(data, &v); err != nil {
 						panic(err)
 					}
 				}
+			}
+		}
 
 		if itemIsPtr {
 			realDest.Set(reflect.Append(realDest, vp))
@@ -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()
 					}
@@ -201,17 +205,18 @@ func sStruct(rows *sql.Rows, dest any) (result RowScan) {
 
 			// json 字符串 反序列化
 			for i, rv := range jFields {
+				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()
-				data := *scanArgs[i].(*[]uint8)
-
-				if len(data) == 0 {
-					continue
-				}
-
 						if err := json.Unmarshal(data, &v); err != nil {
 							panic(err)
 						}
 					}
+				}
+			}
 
 			if realDest.Kind() == reflect.Ptr {
 				realDest.Set(vp)

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)
 }