✨ improve the functions related to commenting on images

utils/paginator.go

@@ -0,0 +1,52 @@
+package utils
+
+import (
+	"gorm.io/gorm"
+)
+
+// 标准分页结构体，接收最原始的DO
+// 建议在外部再建一个字段一样的结构体，用以将DO转换成DTO或VO
+type Page[T any] struct {
+	CurrentPage int64 `json:"currentPage"`
+	PageSize    int64 `json:"pageSize"`
+	Total       int64 `json:"total"`
+	Pages       int64 `json:"pages"`
+	Data        []T   `json:"data"`
+}
+
+// 各种查询条件先在query设置好后再放进来
+func (page *Page[T]) SelectPages(query *gorm.DB) (e error) {
+	var model T
+	query.Model(&model).Count(&page.Total)
+	if page.Total == 0 {
+		page.Data = []T{}
+		return
+	}
+	e = query.Model(&model).Scopes(Paginate(page)).Find(&page.Data).Error
+	return
+}
+
+func Paginate[T any](page *Page[T]) func(db *gorm.DB) *gorm.DB {
+	return func(db *gorm.DB) *gorm.DB {
+		if page.CurrentPage <= 0 {
+			page.CurrentPage = 1
+		}
+		switch {
+		case page.PageSize > 10000:
+			page.PageSize = 10000 // 限制一下分页大小
+		case page.PageSize <= 0:
+			page.PageSize = 10
+		}
+		page.Pages = page.Total / page.PageSize
+		if page.Total%page.PageSize != 0 {
+			page.Pages++
+		}
+		p := page.CurrentPage
+		if page.CurrentPage > page.Pages {
+			p = page.Pages
+		}
+		size := page.PageSize
+		offset := int((p - 1) * size)
+		return db.Offset(offset).Limit(int(size))
+	}
+}