// NextPageURL extracts the pagination structure from a JSON response and returns the "next" link, if one is present.
// It assumes that the links are available in a "links" element of the top-level response object.
// If this is not the case, override NextPageURL on your result type.
func (current LinkedPageBase) NextPageURL() (string, error) {
var path []string
var key string
if current.LinkPath == nil {
path = []string{"links", "next"}
} else {
path = current.LinkPath
}
submap, ok := current.Body.(map[string]interface{})
if !ok {
err := gophercloud.ErrUnexpectedType{}
err.Expected = "map[string]interface{}"
err.Actual = fmt.Sprintf("%v", reflect.TypeOf(current.Body))
return "", err
}
for {
key, path = path[0], path[1:len(path)]
value, ok := submap[key]
if !ok {
return "", nil
}
if len(path) > 0 {
submap, ok = value.(map[string]interface{})
if !ok {
err := gophercloud.ErrUnexpectedType{}
err.Expected = "map[string]interface{}"
err.Actual = fmt.Sprintf("%v", reflect.TypeOf(value))
return "", err
}
} else {
if value == nil {
// Actual null element.
return "", nil
}
url, ok := value.(string)
if !ok {
err := gophercloud.ErrUnexpectedType{}
err.Expected = "string"
err.Actual = fmt.Sprintf("%v", reflect.TypeOf(value))
return "", err
}
return url, nil
}
}
}
// IsEmpty satisifies the IsEmpty method of the Page interface
func (current SinglePageBase) IsEmpty() (bool, error) {
if b, ok := current.Body.([]interface{}); ok {
return len(b) == 0, nil
}
err := gophercloud.ErrUnexpectedType{}
err.Expected = "[]interface{}"
err.Actual = fmt.Sprintf("%v", reflect.TypeOf(current.Body))
return true, err
}
// AllPages returns all the pages from a `List` operation in a single page,
// allowing the user to retrieve all the pages at once.
func (p Pager) AllPages() (Page, error) {
// pagesSlice holds all the pages until they get converted into as Page Body.
var pagesSlice []interface{}
// body will contain the final concatenated Page body.
var body reflect.Value
// Grab a test page to ascertain the page body type.
testPage, err := p.fetchNextPage(p.initialURL)
if err != nil {
return nil, err
}
// Store the page type so we can use reflection to create a new mega-page of
// that type.
pageType := reflect.TypeOf(testPage)
// if it's a single page, just return the testPage (first page)
if _, found := pageType.FieldByName("SinglePageBase"); found {
return testPage, nil
}
// Switch on the page body type. Recognized types are `map[string]interface{}`,
// `[]byte`, and `[]interface{}`.
switch testPage.GetBody().(type) {
case map[string]interface{}:
// key is the map key for the page body if the body type is `map[string]interface{}`.
var key string
// Iterate over the pages to concatenate the bodies.
err = p.EachPage(func(page Page) (bool, error) {
b := page.GetBody().(map[string]interface{})
for k := range b {
// If it's a linked page, we don't want the `links`, we want the other one.
if !strings.HasSuffix(k, "links") {
key = k
}
}
switch keyType := b[key].(type) {
case map[string]interface{}:
pagesSlice = append(pagesSlice, keyType)
case []interface{}:
pagesSlice = append(pagesSlice, b[key].([]interface{})...)
default:
return false, fmt.Errorf("Unsupported page body type: %+v", keyType)
}
return true, nil
})
if err != nil {
return nil, err
}
// Set body to value of type `map[string]interface{}`
body = reflect.MakeMap(reflect.MapOf(reflect.TypeOf(key), reflect.TypeOf(pagesSlice)))
body.SetMapIndex(reflect.ValueOf(key), reflect.ValueOf(pagesSlice))
case []byte:
// Iterate over the pages to concatenate the bodies.
err = p.EachPage(func(page Page) (bool, error) {
b := page.GetBody().([]byte)
pagesSlice = append(pagesSlice, b)
// seperate pages with a comma
pagesSlice = append(pagesSlice, []byte{10})
return true, nil
})
if err != nil {
return nil, err
}
if len(pagesSlice) > 0 {
// Remove the trailing comma.
pagesSlice = pagesSlice[:len(pagesSlice)-1]
}
var b []byte
// Combine the slice of slices in to a single slice.
for _, slice := range pagesSlice {
b = append(b, slice.([]byte)...)
}
// Set body to value of type `bytes`.
body = reflect.New(reflect.TypeOf(b)).Elem()
body.SetBytes(b)
case []interface{}:
// Iterate over the pages to concatenate the bodies.
err = p.EachPage(func(page Page) (bool, error) {
b := page.GetBody().([]interface{})
pagesSlice = append(pagesSlice, b...)
return true, nil
})
if err != nil {
return nil, err
}
// Set body to value of type `[]interface{}`
body = reflect.MakeSlice(reflect.TypeOf(pagesSlice), len(pagesSlice), len(pagesSlice))
for i, s := range pagesSlice {
body.Index(i).Set(reflect.ValueOf(s))
}
default:
err := gophercloud.ErrUnexpectedType{}
err.Expected = "map[string]interface{}/[]byte/[]interface{}"
err.Actual = fmt.Sprintf("%v", reflect.TypeOf(testPage.GetBody()))
return nil, err
}
// Each `Extract*` function is expecting a specific type of page coming back,
// otherwise the type assertion in those functions will fail. pageType is needed
// to create a type in this method that has the same type that the `Extract*`
// function is expecting and set the Body of that object to the concatenated
// pages.
page := reflect.New(pageType)
// Set the page body to be the concatenated pages.
page.Elem().FieldByName("Body").Set(body)
// Set any additional headers that were pass along. The `objectstorage` pacakge,
// for example, passes a Content-Type header.
h := make(http.Header)
for k, v := range p.Headers {
h.Add(k, v)
}
page.Elem().FieldByName("Header").Set(reflect.ValueOf(h))
// Type assert the page to a Page interface so that the type assertion in the
// `Extract*` methods will work.
return page.Elem().Interface().(Page), err
}