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pager.go
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pager.go
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package common
import (
"fmt"
"net/url"
"strconv"
"github.com/gin-gonic/gin"
)
type Pager struct {
TotalItems int
ItemsInResultSet int
ItemFirst int
ItemLast int
Page int
PerPage int
QueryOffset int
PreviousLink string
NextLink string
URL *url.URL
}
func NewPager(c *gin.Context, baseURL string, defaultPerPage int) (*Pager, error) {
_baseURL, err := url.Parse(baseURL)
if err != nil {
return nil, err
}
pager := &Pager{
URL: _baseURL,
}
page := c.DefaultQuery("page", "1")
perPage := c.DefaultQuery("per_page", strconv.Itoa(defaultPerPage))
pager.Page, _ = strconv.Atoi(page)
pager.PerPage, _ = strconv.Atoi(perPage)
if pager.Page > 1 {
pager.QueryOffset = (pager.Page - 1) * pager.PerPage
}
// Do not let users request hundreds of thousands of items at once.
if pager.PerPage > 1000 {
pager.PerPage = 1000
}
pager.ItemFirst = pager.QueryOffset + 1
return pager, nil
}
func (pager *Pager) SetCounts(totalItems, itemsInResultSet int) {
pager.TotalItems = totalItems
pager.ItemsInResultSet = itemsInResultSet
pager.ItemLast = pager.QueryOffset + itemsInResultSet
queryValues := pager.URL.Query()
queryValues["per_page"] = []string{strconv.Itoa(pager.PerPage)}
if pager.Page > 1 {
queryValues["page"] = []string{strconv.Itoa(pager.Page - 1)}
pager.PreviousLink = fmt.Sprintf("%s?%s", pager.URL.Path, queryValues.Encode())
}
if totalItems > pager.ItemLast {
queryValues["page"] = []string{strconv.Itoa(pager.Page + 1)}
pager.NextLink = fmt.Sprintf("%s?%s", pager.URL.Path, queryValues.Encode())
}
}