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// A facebook graph api client in go.
// https://github.com/huandu/facebook/
//
// Copyright 2012 - 2015, Huan Du
// Licensed under the MIT license
// https://github.com/huandu/facebook/blob/master/LICENSE
package facebook
import (
"bytes"
"fmt"
"net/http"
)
type pagingData struct {
Data []Result `facebook:",required"`
Paging *pagingNavigator
}
type pagingNavigator struct {
Previous string
Next string
}
func newPagingResult(session *Session, res Result) (*PagingResult, error) {
// quick check whether Result is a paging response.
if _, ok := res["data"]; !ok {
return nil, fmt.Errorf("current Result is not a paging response.")
}
pr := &PagingResult{
session: session,
}
paging := &pr.paging
err := res.Decode(paging)
if err != nil {
return nil, err
}
if paging.Paging != nil {
pr.previous = paging.Paging.Previous
pr.next = paging.Paging.Next
}
return pr, nil
}
// Get current data.
func (pr *PagingResult) Data() []Result {
return pr.paging.Data
}
// Decodes the current full result to a struct. See Result#Decode.
func (pr *PagingResult) Decode(v interface{}) (err error) {
res := Result{
"data": pr.Data(),
}
return res.Decode(v)
}
// Read previous page.
func (pr *PagingResult) Previous() (noMore bool, err error) {
if !pr.HasPrevious() {
noMore = true
return
}
return pr.navigate(&pr.previous)
}
// Read next page.
func (pr *PagingResult) Next() (noMore bool, err error) {
if !pr.HasNext() {
noMore = true
return
}
return pr.navigate(&pr.next)
}
// Check whether there is previous page.
func (pr *PagingResult) HasPrevious() bool {
return pr.previous != ""
}
// Check whether there is next page.
func (pr *PagingResult) HasNext() bool {
return pr.next != ""
}
func (pr *PagingResult) navigate(url *string) (noMore bool, err error) {
var pagingUrl string
// add session information in paging url.
params := Params{}
pr.session.prepareParams(params)
if len(params) == 0 {
pagingUrl = *url
} else {
buf := &bytes.Buffer{}
buf.WriteString(*url)
buf.WriteRune('&')
params.Encode(buf)
pagingUrl = buf.String()
}
var request *http.Request
var res Result
request, err = http.NewRequest("GET", pagingUrl, nil)
if err != nil {
return
}
res, err = pr.session.Request(request)
if err != nil {
return
}
if pr.paging.Paging != nil {
pr.paging.Paging.Next = ""
pr.paging.Paging.Previous = ""
}
paging := &pr.paging
err = res.Decode(paging)
if err != nil {
return
}
if paging.Paging == nil || len(paging.Data) == 0 {
*url = ""
noMore = true
} else {
pr.previous = paging.Paging.Previous
pr.next = paging.Paging.Next
}
return
}
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