initial commit. Cloned timetracker repository

app/utils/pagination/pagination.go

@@ -0,0 +1,63 @@
+package pagination
+
+import (
+	"strconv"
+
+	"github.com/gofiber/fiber/v3"
+	"gorm.io/gorm"
+)
+
+type Paging struct {
+	Page     uint `json:"page_number" example:"5"`
+	Elements uint `json:"elements_per_page" example:"30"`
+}
+
+func (p Paging) Offset() int {
+	return int(p.Elements) * int(p.Page-1)
+}
+
+func (p Paging) Limit() int {
+	return int(p.Elements)
+}
+
+type Found[T any] struct {
+	Items []T  `json:"items,omitempty"`
+	Count uint `json:"items_count" example:"56"`
+}
+
+func Paginate[T any](paging Paging, stmt *gorm.DB) (Found[T], error) {
+	var items []T
+	var count int64
+
+	base := stmt.Session(&gorm.Session{})
+
+	countDB := stmt.Session(&gorm.Session{
+		NewDB: true, // critical: do NOT reuse statement
+	})
+
+	if err := countDB.
+		Table("(?) as sub", base).
+		Count(&count).Error; err != nil {
+		return Found[T]{}, err
+	}
+
+	err := base.
+		Offset(paging.Offset()).
+		Limit(paging.Limit()).
+		Find(&items).
+		Error
+	if err != nil {
+		return Found[T]{}, err
+	}
+
+	return Found[T]{
+		Items: items,
+		Count: uint(count),
+	}, err
+}
+
+func ParsePagination(c *fiber.Ctx) Paging {
+	pageNum, _ := strconv.ParseInt((*c).Query("p", "1"), 10, 64)
+	pageSize, _ := strconv.ParseInt((*c).Query("elems", "10"), 10, 64)
+	return Paging{Page: uint(pageNum), Elements: uint(pageSize)}
+}