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pager.go
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pager.go
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package recurly
import (
"context"
"encoding/xml"
"errors"
"fmt"
"net/url"
"strconv"
"time"
)
// Pager paginates records.
type Pager interface {
// Count returns a total count of the request. Calling this function
// more than once will return the value from the first call.
Count(ctx context.Context) (int, error)
// Next returns true if there is a next result expected, or false if
// there is no next result.
Next() bool
// Cursor returns the next cursor (if available).
Cursor() string
// Fetch fetches results of a single page and populates dst with the results.
// For use in a for loop with Next().
Fetch(ctx context.Context, dst interface{}) error
// FetchAll fetches all of the pages recurly has available for the result
// set and populates dst with the results.
FetchAll(ctx context.Context, dst interface{}) error
}
var _ Pager = &pager{}
// pager paginates API calls.
type pager struct {
client *Client
method string
path string
opts *PagerOptions
count *int
cursor string
expectResults bool
}
// returns a new pager and initializes params if nil. It ensures no cursor
// is set.
func (c *Client) newPager(method, path string, opts *PagerOptions) *pager {
if opts == nil {
opts = &PagerOptions{}
}
return &pager{
client: c,
method: method,
path: path,
opts: opts,
cursor: opts.Cursor,
expectResults: true,
}
}
func (p *pager) Count(ctx context.Context) (int, error) {
if p.count != nil {
return *p.count, nil
}
req, err := p.client.newPagerRequest("HEAD", p.path, p.opts, nil)
if err != nil {
return 0, err
}
resp, err := p.client.do(ctx, req, nil)
if err != nil {
return 0, err
}
if count := resp.Header.Get("X-Records"); count == "" {
return 0, nil
} else if i, err := strconv.Atoi(count); err != nil {
return 0, err
} else {
p.count = &i
return i, nil
}
}
func (p *pager) Next() bool { return p.expectResults }
// fetch retrieves the results and populates dst, setting the next
// cursor.
func (p *pager) Fetch(ctx context.Context, dst interface{}) error {
select {
default:
case <-ctx.Done():
return ctx.Err()
}
if !p.expectResults {
return errors.New("no more results")
}
p.opts.Cursor = p.cursor
req, err := p.client.newPagerRequest(p.method, p.path, p.opts, nil)
if err != nil {
return err
}
var unmarshaler struct {
XMLName xml.Name
Account []Account `xml:"account"`
Adjustment []Adjustment `xml:"adjustment"`
AddOn []AddOn `xml:"add_on"`
Coupon []Coupon `xml:"coupon"`
CreditPayment []CreditPayment `xml:"credit_payment"`
ExportDate []ExportDate `xml:"export_date"`
ExportFile []ExportFile `xml:"export_file"`
Invoice []Invoice `xml:"invoice"`
Note []Note `xml:"note"`
Plan []Plan `xml:"plan"`
Redemption []Redemption `xml:"redemption"`
ShippingAddress []ShippingAddress `xml:"shipping_address"`
ShippingMethod []ShippingMethod `xml:"shipping_method"`
Subscription []Subscription `xml:"subscription"`
Transaction []Transaction `xml:"transaction"`
Item []Item `xml:"item"`
}
resp, err := p.client.do(ctx, req, &unmarshaler)
if err != nil {
p.expectResults = false
return err
} else if p.cursor = resp.cursor; p.cursor == "" {
p.expectResults = false
}
// note: this may be a good candidate for a code generator.
switch v := dst.(type) {
case *[]Account:
*v = unmarshaler.Account
case *[]Adjustment:
*v = unmarshaler.Adjustment
case *[]AddOn:
*v = unmarshaler.AddOn
case *[]Coupon:
*v = unmarshaler.Coupon
case *[]CreditPayment:
*v = unmarshaler.CreditPayment
case *[]ExportDate:
*v = unmarshaler.ExportDate
case *[]ExportFile:
*v = unmarshaler.ExportFile
case *[]Invoice:
*v = unmarshaler.Invoice
case *[]Note:
*v = unmarshaler.Note
case *[]Plan:
*v = unmarshaler.Plan
case *[]Redemption:
*v = unmarshaler.Redemption
case *[]ShippingAddress:
*v = unmarshaler.ShippingAddress
case *[]ShippingMethod:
*v = unmarshaler.ShippingMethod
case *[]Subscription:
*v = unmarshaler.Subscription
case *[]Transaction:
*v = unmarshaler.Transaction
case *[]Item:
*v = unmarshaler.Item
default:
return fmt.Errorf("unknown type used for pagination: %T", dst)
}
return nil
}
func (p *pager) FetchAll(ctx context.Context, dst interface{}) error {
// Reduce HTTP calls needed by setting pagination to Recurly's max of 200.
p.opts.PerPage = 200
// note: this may be a good candidate for a code generator.
switch v := dst.(type) {
case *[]Account:
var all []Account
for p.Next() {
var dst []Account
if err := p.Fetch(ctx, &dst); err != nil {
return err
}
all = append(all, dst...)
}
*v = all
case *[]Adjustment:
var all []Adjustment
for p.Next() {
var dst []Adjustment
if err := p.Fetch(ctx, &dst); err != nil {
return err
}
all = append(all, dst...)
}
*v = all
case *[]AddOn:
var all []AddOn
for p.Next() {
var dst []AddOn
if err := p.Fetch(ctx, &dst); err != nil {
return err
}
all = append(all, dst...)
}
*v = all
case *[]Coupon:
var all []Coupon
for p.Next() {
var dst []Coupon
if err := p.Fetch(ctx, &dst); err != nil {
return err
}
all = append(all, dst...)
}
*v = all
case *[]CreditPayment:
var all []CreditPayment
for p.Next() {
var dst []CreditPayment
if err := p.Fetch(ctx, &dst); err != nil {
return err
}
all = append(all, dst...)
}
*v = all
case *[]Invoice:
var all []Invoice
for p.Next() {
var dst []Invoice
if err := p.Fetch(ctx, &dst); err != nil {
return err
}
all = append(all, dst...)
}
*v = all
case *[]Note:
var all []Note
for p.Next() {
var dst []Note
if err := p.Fetch(ctx, &dst); err != nil {
return err
}
all = append(all, dst...)
}
*v = all
case *[]Plan:
var all []Plan
for p.Next() {
var dst []Plan
if err := p.Fetch(ctx, &dst); err != nil {
return err
}
all = append(all, dst...)
}
*v = all
case *[]Redemption:
var all []Redemption
for p.Next() {
var dst []Redemption
if err := p.Fetch(ctx, &dst); err != nil {
return err
}
all = append(all, dst...)
}
*v = all
case *[]ShippingAddress:
var all []ShippingAddress
for p.Next() {
var dst []ShippingAddress
if err := p.Fetch(ctx, &dst); err != nil {
return err
}
all = append(all, dst...)
}
*v = all
case *[]ShippingMethod:
var all []ShippingMethod
for p.Next() {
var dst []ShippingMethod
if err := p.Fetch(ctx, &dst); err != nil {
return err
}
all = append(all, dst...)
}
*v = all
case *[]Subscription:
var all []Subscription
for p.Next() {
var dst []Subscription
if err := p.Fetch(ctx, &dst); err != nil {
return err
}
all = append(all, dst...)
}
*v = all
case *[]Transaction:
var all []Transaction
for p.Next() {
var dst []Transaction
if err := p.Fetch(ctx, &dst); err != nil {
return err
}
all = append(all, dst...)
}
*v = all
default:
return fmt.Errorf("unknown type used for pagination: %T", dst)
}
return nil
}
func (p *pager) Cursor() string { return p.cursor }
// PagerOptions are used to send pagination parameters with paginated requests.
type PagerOptions struct {
// Results per page. If not provided, Recurly defaults to 50.
PerPage int
// The field to sort by (e.g. created_at). See Recurly's documentation.
Sort string
// asc or desc
Order string
// Returns records greater than or equal to BeginTime.
BeginTime NullTime
// Returns records less than or equal to EndTime.
EndTime NullTime
State string // supported by some endpoints. Check Recurly's documenation.
Type string // supported by some endpoints. Check Recurly's documentation.
// query is for any one-off URL params used by a specific endpoint.
// Values sent as time.Time or recurly.NullTime will be automatically
// converted to a valid datetime format for Recurly.
query query
// Cursor is set internally by the library. If you are paginating
// records non-consecutively and obtained the next cursor, you can set it
// as the starting cursor here to continue where you left off.
//
// Use Pager.Cursor() to obtain the next cursor.
Cursor string
}
type query map[string]interface{}
func (q query) append(u *url.URL) {
if len(q) == 0 {
return
}
vals := u.Query()
for key, val := range q {
switch v := val.(type) {
case string:
if v != "" {
vals.Add(key, v)
}
case time.Time:
if !v.IsZero() {
vals.Add(key, v.UTC().Format(DateTimeFormat))
}
case NullTime:
if _, ok := v.Value(); ok {
vals.Add(key, v.String())
}
case bool:
vals.Add(key, fmt.Sprintf("%t", v))
case int, int64, uint, uint64:
vals.Add(key, fmt.Sprintf("%d", v))
default:
vals.Add(key, fmt.Sprintf("%v", val))
}
}
u.RawQuery = vals.Encode()
}
// append appends params to a URL.
func (p PagerOptions) append(u *url.URL) {
if p.query == nil {
p.query = map[string]interface{}{}
}
if p.PerPage > 0 {
p.query["per_page"] = p.PerPage
}
p.query["begin_time"] = p.BeginTime.String()
p.query["end_time"] = p.EndTime.String()
p.query["sort"] = p.Sort
p.query["order"] = p.Order
p.query["state"] = p.State
p.query["type"] = p.Type
p.query["cursor"] = p.Cursor
p.query.append(u)
}