81 lines
1.8 KiB
Go
81 lines
1.8 KiB
Go
package page
|
|
|
|
import (
|
|
"math"
|
|
"strconv"
|
|
|
|
"github.com/labstack/echo/v4"
|
|
)
|
|
|
|
const (
|
|
// DefaultItemsPerPage stores the default amount of items per page
|
|
DefaultItemsPerPage = 20
|
|
|
|
// PageQueryKey stores the query key used to indicate the current page
|
|
PageQueryKey = "page"
|
|
)
|
|
|
|
// Pager provides a mechanism to allow a user to page results via a query parameter
|
|
type Pager struct {
|
|
// Items stores the total amount of items in the result set
|
|
Items int
|
|
|
|
// Page stores the current page number
|
|
Page int
|
|
|
|
// ItemsPerPage stores the amount of items to display per page
|
|
ItemsPerPage int
|
|
|
|
// Pages stores the total amount of pages in the result set
|
|
Pages int
|
|
}
|
|
|
|
// NewPager creates a new Pager
|
|
func NewPager(ctx echo.Context, itemsPerPage int) Pager {
|
|
p := Pager{
|
|
ItemsPerPage: itemsPerPage,
|
|
Page: 1,
|
|
}
|
|
|
|
if page := ctx.QueryParam(PageQueryKey); page != "" {
|
|
if pageInt, err := strconv.Atoi(page); err == nil {
|
|
if pageInt > 0 {
|
|
p.Page = pageInt
|
|
}
|
|
}
|
|
}
|
|
|
|
return p
|
|
}
|
|
|
|
// SetItems sets the amount of items in total for the pager and calculate the amount
|
|
// of total pages based off on the item per page.
|
|
// This should be used rather than setting either items or pages directly.
|
|
func (p *Pager) SetItems(items int) {
|
|
p.Items = items
|
|
p.Pages = int(math.Ceil(float64(items) / float64(p.ItemsPerPage)))
|
|
|
|
if p.Page > p.Pages {
|
|
p.Page = p.Pages
|
|
}
|
|
}
|
|
|
|
// IsBeginning determines if the pager is at the beginning of the pages
|
|
func (p Pager) IsBeginning() bool {
|
|
return p.Page == 1
|
|
}
|
|
|
|
// IsEnd determines if the pager is at the end of the pages
|
|
func (p Pager) IsEnd() bool {
|
|
return p.Page >= p.Pages
|
|
}
|
|
|
|
// GetOffset determines the offset of the results in order to get the items for
|
|
// the current page
|
|
func (p Pager) GetOffset() int {
|
|
if p.Page == 0 {
|
|
p.Page = 1
|
|
}
|
|
return (p.Page - 1) * p.ItemsPerPage
|
|
}
|