fix null err

dao/dao-exam-record.go

@@ -309,14 +309,15 @@ func AdminExamRecordDetail(id int) *result.Result {
 
 	// 题目答案, 用户答案
 	sqlStr := "select er.answer from exam_record er where er.id = ? and er.delete_at is null"
-	var answerStr string
+	// ! 20240305 这里修改answer为*string类型 数据库为null值会报错
+	var answerStr *string
 	err := config.DB.Get(&answerStr, sqlStr, id)
 	if err != nil {
 		return result.UNKNOW_ERROR.SetMsg(err.Error())
 	}
 
 	var avs []*vo.AnswerVo
-	err = json.Unmarshal([]byte(answerStr), &avs)
+	err = json.Unmarshal([]byte(*answerStr), &avs)
 	if err != nil {
 		return result.FORMATE_ERROR
 	}