blob: f6e15be35da9ade73f53a19de5fb03cbcb0ca0ae [file] [log] [blame]
// Copyright 2011 Google Inc. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package googleapi contains the common code shared by all Google API
// libraries.
package googleapi // import ""
import (
// ContentTyper is an interface for Readers which know (or would like
// to override) their Content-Type. If a media body doesn't implement
// ContentTyper, the type is sniffed from the content using
// http.DetectContentType.
type ContentTyper interface {
ContentType() string
// A SizeReaderAt is a ReaderAt with a Size method.
// An io.SectionReader implements SizeReaderAt.
type SizeReaderAt interface {
Size() int64
// ServerResponse is embedded in each Do response and
// provides the HTTP status code and header sent by the server.
type ServerResponse struct {
// HTTPStatusCode is the server's response status code.
// When using a resource method's Do call, this will always be in the 2xx range.
HTTPStatusCode int
// Header contains the response header fields from the server.
Header http.Header
const (
Version = "0.5"
// UserAgent is the header string used to identify this package.
UserAgent = "google-api-go-client/" + Version
// The default chunk size to use for resumable uploads if not specified by the user.
DefaultUploadChunkSize = 8 * 1024 * 1024
// The minimum chunk size that can be used for resumable uploads. All
// user-specified chunk sizes must be multiple of this value.
MinUploadChunkSize = 256 * 1024
// Error contains an error response from the server.
type Error struct {
// Code is the HTTP response status code and will always be populated.
Code int `json:"code"`
// Message is the server response message and is only populated when
// explicitly referenced by the JSON server response.
Message string `json:"message"`
// Body is the raw response returned by the server.
// It is often but not always JSON, depending on how the request fails.
Body string
// Header contains the response header fields from the server.
Header http.Header
Errors []ErrorItem
// ErrorItem is a detailed error code & message from the Google API frontend.
type ErrorItem struct {
// Reason is the typed error code. For example: "some_example".
Reason string `json:"reason"`
// Message is the human-readable description of the error.
Message string `json:"message"`
func (e *Error) Error() string {
if len(e.Errors) == 0 && e.Message == "" {
return fmt.Sprintf("googleapi: got HTTP response code %d with body: %v", e.Code, e.Body)
var buf bytes.Buffer
fmt.Fprintf(&buf, "googleapi: Error %d: ", e.Code)
if e.Message != "" {
fmt.Fprintf(&buf, "%s", e.Message)
if len(e.Errors) == 0 {
return strings.TrimSpace(buf.String())
if len(e.Errors) == 1 && e.Errors[0].Message == e.Message {
fmt.Fprintf(&buf, ", %s", e.Errors[0].Reason)
return buf.String()
fmt.Fprintln(&buf, "\nMore details:")
for _, v := range e.Errors {
fmt.Fprintf(&buf, "Reason: %s, Message: %s\n", v.Reason, v.Message)
return buf.String()
type errorReply struct {
Error *Error `json:"error"`
// CheckResponse returns an error (of type *Error) if the response
// status code is not 2xx.
func CheckResponse(res *http.Response) error {
if res.StatusCode >= 200 && res.StatusCode <= 299 {
return nil
slurp, err := ioutil.ReadAll(res.Body)
if err == nil {
jerr := new(errorReply)
err = json.Unmarshal(slurp, jerr)
if err == nil && jerr.Error != nil {
if jerr.Error.Code == 0 {
jerr.Error.Code = res.StatusCode
jerr.Error.Body = string(slurp)
return jerr.Error
return &Error{
Code: res.StatusCode,
Body: string(slurp),
Header: res.Header,
// IsNotModified reports whether err is the result of the
// server replying with http.StatusNotModified.
// Such error values are sometimes returned by "Do" methods
// on calls when If-None-Match is used.
func IsNotModified(err error) bool {
if err == nil {
return false
ae, ok := err.(*Error)
return ok && ae.Code == http.StatusNotModified
// CheckMediaResponse returns an error (of type *Error) if the response
// status code is not 2xx. Unlike CheckResponse it does not assume the
// body is a JSON error document.
// It is the caller's responsibility to close res.Body.
func CheckMediaResponse(res *http.Response) error {
if res.StatusCode >= 200 && res.StatusCode <= 299 {
return nil
slurp, _ := ioutil.ReadAll(io.LimitReader(res.Body, 1<<20))
return &Error{
Code: res.StatusCode,
Body: string(slurp),
type MarshalStyle bool
var WithDataWrapper = MarshalStyle(true)
var WithoutDataWrapper = MarshalStyle(false)
func (wrap MarshalStyle) JSONReader(v interface{}) (io.Reader, error) {
buf := new(bytes.Buffer)
if wrap {
buf.Write([]byte(`{"data": `))
err := json.NewEncoder(buf).Encode(v)
if err != nil {
return nil, err
if wrap {
return buf, nil
// endingWithErrorReader from r until it returns an error. If the
// final error from r is io.EOF and e is non-nil, e is used instead.
type endingWithErrorReader struct {
r io.Reader
e error
func (er endingWithErrorReader) Read(p []byte) (n int, err error) {
n, err = er.r.Read(p)
if err == io.EOF && er.e != nil {
err = er.e
// countingWriter counts the number of bytes it receives to write, but
// discards them.
type countingWriter struct {
n *int64
func (w countingWriter) Write(p []byte) (int, error) {
*w.n += int64(len(p))
return len(p), nil
// ProgressUpdater is a function that is called upon every progress update of a resumable upload.
// This is the only part of a resumable upload (from googleapi) that is usable by the developer.
// The remaining usable pieces of resumable uploads is exposed in each auto-generated API.
type ProgressUpdater func(current, total int64)
type MediaOption interface {
setOptions(o *MediaOptions)
type contentTypeOption string
func (ct contentTypeOption) setOptions(o *MediaOptions) {
o.ContentType = string(ct)
if o.ContentType == "" {
o.ForceEmptyContentType = true
// ContentType returns a MediaOption which sets the Content-Type header for media uploads.
// If ctype is empty, the Content-Type header will be omitted.
func ContentType(ctype string) MediaOption {
return contentTypeOption(ctype)
type chunkSizeOption int
func (cs chunkSizeOption) setOptions(o *MediaOptions) {
size := int(cs)
if size%MinUploadChunkSize != 0 {
size += MinUploadChunkSize - (size % MinUploadChunkSize)
o.ChunkSize = size
// ChunkSize returns a MediaOption which sets the chunk size for media uploads.
// size will be rounded up to the nearest multiple of 256K.
// Media which contains fewer than size bytes will be uploaded in a single request.
// Media which contains size bytes or more will be uploaded in separate chunks.
// If size is zero, media will be uploaded in a single request.
func ChunkSize(size int) MediaOption {
return chunkSizeOption(size)
// MediaOptions stores options for customizing media upload. It is not used by developers directly.
type MediaOptions struct {
ContentType string
ForceEmptyContentType bool
ChunkSize int
// ProcessMediaOptions stores options from opts in a MediaOptions.
// It is not used by developers directly.
func ProcessMediaOptions(opts []MediaOption) *MediaOptions {
mo := &MediaOptions{ChunkSize: DefaultUploadChunkSize}
for _, o := range opts {
return mo
func ResolveRelative(basestr, relstr string) string {
u, _ := url.Parse(basestr)
rel, _ := url.Parse(relstr)
u = u.ResolveReference(rel)
us := u.String()
us = strings.Replace(us, "%7B", "{", -1)
us = strings.Replace(us, "%7D", "}", -1)
return us
// Expand subsitutes any {encoded} strings in the URL passed in using
// the map supplied.
// This calls SetOpaque to avoid encoding of the parameters in the URL path.
func Expand(u *url.URL, expansions map[string]string) {
escaped, unescaped, err := uritemplates.Expand(u.Path, expansions)
if err == nil {
u.Path = unescaped
u.RawPath = escaped
// CloseBody is used to close res.Body.
// Prior to calling Close, it also tries to Read a small amount to see an EOF.
// Not seeing an EOF can prevent HTTP Transports from reusing connections.
func CloseBody(res *http.Response) {
if res == nil || res.Body == nil {
// Justification for 3 byte reads: two for up to "\r\n" after
// a JSON/XML document, and then 1 to see EOF if we haven't yet.
// TODO(bradfitz): detect Go 1.3+ and skip these reads.
// See
// and
buf := make([]byte, 1)
for i := 0; i < 3; i++ {
_, err := res.Body.Read(buf)
if err != nil {
// VariantType returns the type name of the given variant.
// If the map doesn't contain the named key or the value is not a []interface{}, "" is returned.
// This is used to support "variant" APIs that can return one of a number of different types.
func VariantType(t map[string]interface{}) string {
s, _ := t["type"].(string)
return s
// ConvertVariant uses the JSON encoder/decoder to fill in the struct 'dst' with the fields found in variant 'v'.
// This is used to support "variant" APIs that can return one of a number of different types.
// It reports whether the conversion was successful.
func ConvertVariant(v map[string]interface{}, dst interface{}) bool {
var buf bytes.Buffer
err := json.NewEncoder(&buf).Encode(v)
if err != nil {
return false
return json.Unmarshal(buf.Bytes(), dst) == nil
// A Field names a field to be retrieved with a partial response.
// See
// Partial responses can dramatically reduce the amount of data that must be sent to your application.
// In order to request partial responses, you can specify the full list of fields
// that your application needs by adding the Fields option to your request.
// Field strings use camelCase with leading lower-case characters to identify fields within the response.
// For example, if your response has a "NextPageToken" and a slice of "Items" with "Id" fields,
// you could request just those fields like this:
// svc.Events.List().Fields("nextPageToken", "items/id").Do()
// or if you were also interested in each Item's "Updated" field, you can combine them like this:
// svc.Events.List().Fields("nextPageToken", "items(id,updated)").Do()
// More information about field formatting can be found here:
// Another way to find field names is through the Google API explorer:
type Field string
// CombineFields combines fields into a single string.
func CombineFields(s []Field) string {
r := make([]string, len(s))
for i, v := range s {
r[i] = string(v)
return strings.Join(r, ",")
// A CallOption is an optional argument to an API call.
// It should be treated as an opaque value by users of Google APIs.
// A CallOption is something that configures an API call in a way that is
// not specific to that API; for instance, controlling the quota user for
// an API call is common across many APIs, and is thus a CallOption.
type CallOption interface {
Get() (key, value string)
// QuotaUser returns a CallOption that will set the quota user for a call.
// The quota user can be used by server-side applications to control accounting.
// It can be an arbitrary string up to 40 characters, and will override UserIP
// if both are provided.
func QuotaUser(u string) CallOption { return quotaUser(u) }
type quotaUser string
func (q quotaUser) Get() (string, string) { return "quotaUser", string(q) }
// UserIP returns a CallOption that will set the "userIp" parameter of a call.
// This should be the IP address of the originating request.
func UserIP(ip string) CallOption { return userIP(ip) }
type userIP string
func (i userIP) Get() (string, string) { return "userIp", string(i) }
// Trace returns a CallOption that enables diagnostic tracing for a call.
// traceToken is an ID supplied by Google support.
func Trace(traceToken string) CallOption { return traceTok(traceToken) }
type traceTok string
func (t traceTok) Get() (string, string) { return "trace", "token:" + string(t) }
// TODO: Fields too