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