feat: key接口完善及错误处理

internal/response/pagination.go

@@ -0,0 +1,74 @@
+package response
+
+import (
+	"math"
+	"strconv"
+
+	"github.com/gin-gonic/gin"
+	"gorm.io/gorm"
+)
+
+const (
+	DefaultPageSize = 15
+	MaxPageSize     = 1000
+)
+
+// Pagination represents the pagination details in a response.
+type Pagination struct {
+	Page       int   `json:"page"`
+	PageSize   int   `json:"page_size"`
+	TotalItems int64 `json:"total_items"`
+	TotalPages int   `json:"total_pages"`
+}
+
+// PaginatedResponse is the standard structure for all paginated API responses.
+type PaginatedResponse struct {
+	Items      interface{} `json:"items"`
+	Pagination Pagination  `json:"pagination"`
+}
+
+// Paginate performs pagination on a GORM query and returns a standardized response.
+// It takes a Gin context, a GORM query builder, and a destination slice for the results.
+func Paginate(c *gin.Context, query *gorm.DB, dest interface{}) (*PaginatedResponse, error) {
+	// 1. Get page and page size from query parameters
+	page, err := strconv.Atoi(c.DefaultQuery("page", "1"))
+	if err != nil || page < 1 {
+		page = 1
+	}
+
+	pageSize, err := strconv.Atoi(c.DefaultQuery("page_size", strconv.Itoa(DefaultPageSize)))
+	if err != nil || pageSize <= 0 {
+		pageSize = DefaultPageSize
+	}
+	if pageSize > MaxPageSize {
+		pageSize = MaxPageSize
+	}
+
+	// 2. Get total count of items
+	var totalItems int64
+	if err := query.Count(&totalItems).Error; err != nil {
+		return nil, err
+	}
+
+	// 3. Calculate offset and total pages
+	offset := (page - 1) * pageSize
+	totalPages := int(math.Ceil(float64(totalItems) / float64(pageSize)))
+
+	// 4. Retrieve the data for the current page
+	if err := query.Limit(pageSize).Offset(offset).Find(dest).Error; err != nil {
+		return nil, err
+	}
+
+	// 5. Construct the paginated response
+	paginatedData := &PaginatedResponse{
+		Items: dest,
+		Pagination: Pagination{
+			Page:       page,
+			PageSize:   pageSize,
+			TotalItems: totalItems,
+			TotalPages: totalPages,
+		},
+	}
+
+	return paginatedData, nil
+}