New route to delete grades

works.go

@@ -192,6 +192,15 @@ func declareAPIAdminWorksRoutes(router *gin.RouterGroup) {
 
 		c.JSON(http.StatusOK, true)
 	})
+
+	gradesRoutes := worksRoutes.Group("/grades/:gid")
+	gradesRoutes.Use(gradeHandler)
+	gradesRoutes.DELETE("", func(c *gin.Context) {
+		g := c.MustGet("grade").(*WorkGrade)
+
+		g.Delete()
+		c.JSON(http.StatusOK, true)
+	})
 }
 
 func declareAPIAuthWorksRoutes(router *gin.RouterGroup) {
@@ -387,6 +396,16 @@ type WorkGrade struct {
 	Comment string    `json:"comment,omitempty"`
 }
 
+func (g WorkGrade) Delete() (int64, error) {
+	if res, err := DBExec("DELETE FROM user_work_grades WHERE id_gradation = ?", g.Id); err != nil {
+		return 0, err
+	} else if nb, err := res.RowsAffected(); err != nil {
+		return 0, err
+	} else {
+		return nb, err
+	}
+}
+
 func (w *Work) GetGrades(cnd string, param ...interface{}) (grades []WorkGrade, err error) {
 	param = append([]interface{}{w.Id}, param...)
 
@@ -410,6 +429,12 @@ func (w *Work) GetGrades(cnd string, param ...interface{}) (grades []WorkGrade,
 	}
 }
 
+func (w *Work) GetGrade(id int64) (g *WorkGrade, err error) {
+	g = new(WorkGrade)
+	err = DBQueryRow("SELECT G.id_gradation, G.id_user, U.login, G.id_work, G.date, G.grade, G.comment FROM user_work_grades G INNER JOIN users U ON U.id_user = G.id_user WHERE id_work = ? AND id_gradation = ?", w.Id, id).Scan(&g.Id, &g.IdUser, &g.Login, &g.IdWork, &g.Date, &g.Grade, &g.Comment)
+	return
+}
+
 func (u *User) GetMyWorkGrade(w *Work) (g WorkGrade, err error) {
 	err = DBQueryRow("SELECT id_gradation, id_user, id_work, date, grade, comment FROM user_work_grades WHERE id_work = ? AND id_user = ? ORDER BY date DESC LIMIT 1", w.Id, u.Id).Scan(&g.Id, &g.IdUser, &g.IdWork, &g.Date, &g.Grade, &g.Comment)
 	return