Pagination and ordering

app/repository/method_list.go

@@ -1,12 +1,30 @@
 package repository
 
 import (
+	"fmt"
 	"repo-pattern/app/repository/smartfilter"
 
 	"gorm.io/gorm"
 	"gorm.io/gorm/schema"
 )
 
+type Pagination struct {
+	Offset int
+	Limit  int
+}
+
+type OrderDirection string
+
+const (
+	OrderASC  OrderDirection = "ASC"
+	OrderDESC OrderDirection = "DESC"
+)
+
+type Order struct {
+	Field     string
+	Direction OrderDirection
+}
+
 type ListMethod[T schema.Tabler] struct {
 	DbConn *gorm.DB
 }
@@ -15,7 +33,36 @@ func (m *ListMethod[T]) Init(dbConn *gorm.DB) {
 	m.DbConn = dbConn
 }
 
-func (m ListMethod[T]) List(filter interface{}) (*[]T, error) {
+func applyOrdering(query *gorm.DB, ordering *[]Order) *gorm.DB {
+	if ordering == nil || len(*ordering) == 0 {
+		return query
+	}
+
+	for _, order := range *ordering {
+		if order.Direction == OrderASC {
+			query = query.Order(order.Field)
+		} else {
+			query = query.Order(fmt.Sprintf("%s %s", order.Field, order.Direction))
+		}
+	}
+	return query
+}
+
+func applyPagination(query *gorm.DB, pagination *Pagination) *gorm.DB {
+	if pagination == nil {
+		return query
+	}
+
+	if pagination.Limit != 0 {
+		query = query.Limit(pagination.Limit)
+	}
+	if pagination.Offset != 0 {
+		query = query.Offset(pagination.Offset)
+	}
+	return query
+}
+
+func (m ListMethod[T]) List(filter interface{}, ordering *[]Order, pagination *Pagination) (*[]T, error) {
 	var (
 		model  T
 		models []T
@@ -26,6 +73,9 @@ func (m ListMethod[T]) List(filter interface{}) (*[]T, error) {
 		return nil, err
 	}
 
+	query = applyOrdering(query, ordering)
+	query = applyPagination(query, pagination)
+
 	query.Find(&models)
 	return &models, nil
 }