api

README

Google APIs Client Library for Go

Getting Started

$ go get google.golang.org/api/tasks/v1
$ go get google.golang.org/api/moderator/v1
$ go get google.golang.org/api/urlshortener/v1
... etc ...

and using:

package main

import (
        "context"
        "net/http"

        "google.golang.org/api/urlshortener/v1"
)

func main() {
        ctx := context.Background()
        svc, err := urlshortener.NewService(ctx)
        // ...
}

• For a longer tutorial, see the Getting Started guide.
• For examples, see the examples directory.
• For support, use the golang-nuts mailing list.

Status

These are auto-generated Go libraries from the Google Discovery Service's JSON description files.

Due to the auto-generated nature of this collection of libraries they may contain breaking changes from one release to the next. The generator itself and the code it produces are considered beta for this reason.

These client libraries are officially supported by Google. However, the libraries are considered complete and are in maintenance mode. This means that we will address critical bugs and security issues but will not add any new features.

If you're working with Google Cloud Platform APIs such as Datastore or Pub/Sub, please use the Cloud Client Libraries for Go instead. These are the new and idiomatic Go libraries targeted specifically at Google Cloud Platform Services.

Authorization

By default, each API will use Google Application Default Credentials for authorization credentials used in calling the API endpoints. This will allow your application to run in many environments without requiring explicit configuration.

// import "google.golang.org/api/sheets/v4"
client, err := sheets.NewService(ctx)

To authorize using a JSON key file, pass option.WithCredentialsFile to the NewService function of the desired package. For example:

client, err := sheets.NewService(ctx, option.WithCredentialsFile("path/to/keyfile.json"))

You can exert more control over authorization by using the golang.org/x/oauth2 package to create an oauth2.TokenSource. Then pass option.WithTokenSource to the NewService function:

tokenSource := ...
svc, err := sheets.NewService(ctx, option.WithTokenSource(tokenSource))

More information

For some more information related to all of the generated clients please read through our package documentation.

Documentation

Overview

Package api is the root of the packages used to access Google Cloud Services. See https://godoc.org/google.golang.org/api for a full list of sub-packages.

Within api there exist numerous clients which connect to Google APIs, and various utility packages.

Client Options

All clients in sub-packages are configurable via client options. These options are described here: https://godoc.org/google.golang.org/api/option.

Authentication and Authorization

All the clients in sub-packages support authentication via Google Application Default Credentials (see https://cloud.google.com/docs/authentication/production), or by providing a JSON key file for a Service Account. See the authentication examples in https://godoc.org/google.golang.org/api/transport for more details.

Versioning and Stability

Due to the auto-generated nature of this collection of libraries, complete APIs or specific versions can appear or go away without notice. As a result, you should always locally vendor any API(s) that your code relies upon.

Google APIs follow semver as specified by https://cloud.google.com/apis/design/versioning. The code generator and the code it produces - the libraries in the google.golang.org/api/... subpackages - are beta.

Note that versioning and stability is strictly not communicated through Go modules. Go modules are used only for dependency management.

Integers

Many parameters are specified using ints. However, underlying APIs might operate on a finer granularity, expecting int64, int32, uint64, or uint32, all of whom have different maximum values. Subsequently, specifying an int parameter in one of these clients may result in an error from the API because the value is too large.

To see the exact type of int that the API expects, you can inspect the API's discovery doc. A global catalogue pointing to the discovery doc of APIs can be found at https://www.googleapis.com/discovery/v1/apis.

ForceSendFields

This field can be found on all Request/Response structs in the generated clients. All of these types have the JSON `omitempty` field tag present on their fields. This means if a type is set to its default value it will not be marshalled. Sometimes you may actually want to send a default value, for instance sending an int of `0`. In this case you can override the `omitempty` feature by adding the field name to the `ForceSendFields` slice. See docs on any struct for more details.

Inspecting errors

An error returned by a client's Do method may be cast to a *googleapi.Error or unwrapped to an *apierror.APIError.

The https://pkg.go.dev/google.golang.org/api/googleapi#Error type is useful for getting the HTTP status code:

if _, err := svc.FooCall().Do(); err != nil {
	if gErr, ok := err.(*googleapi.Error); ok {
		fmt.Println("Status code: %v", gErr.Code)
	}
}

The https://pkg.go.dev/github.com/googleapis/gax-go/v2/apierror#APIError type is useful for inspecting structured details of the underlying API response, such as the reason for the error and the error domain, which is typically the registered service name of the tool or product that generated the error:

if _, err := svc.FooCall().Do(); err != nil {
	var aErr *apierror.APIError
	if ok := errors.As(err, &aErr); ok {
		fmt.Println("Reason: %s", aErr.Reason())
		fmt.Println("Domain: %s", aErr.Domain())
	}
}

Polling Operations

If an API call returns an Operation, that means it could take some time to complete the work initiated by the API call. Applications that are interested in the end result of the operation they initiated should wait until the Operation.Done field indicates it is finished. To do this, use the service's Operation client, and a loop, like so:

  import (
		gax "github.com/googleapis/gax-go/v2"
  )

  // existing application code...

  // API call that returns an Operation.
	 op, err := myApiClient.CalculateFoo().Do()
	 if err != nil {
		// handle err
	 }

	 operationsService = myapi.NewOperationsService(myApiClient)
  pollingBackoff := gax.Backoff{
	    Initial:    time.Second,
	    Max:        time.Minute, // Max time between polling attempts.
	    Multiplier: 2,
  }
	 for {
		if op.Done {
			break
		}
		// not done, sleep with backoff, then poll again
		if err := gax.Sleep(ctx, pollingBackoff.Pause()); err != nil {
			// handle error
		}
		op, err := operationsService.Get(op.Name).Do()
		if err != nil {
			// handle error
		}
	 }

	 if op.Error != nil {
		// handle operation err
	 }

	 // Do something with the response
	 fmt.Println(op.Response)