mirror of
https://github.com/rclone/rclone.git
synced 2024-12-12 10:12:41 +01:00
131 lines
4.1 KiB
Markdown
131 lines
4.1 KiB
Markdown
|
# Getting Started with the Google APIs for Go
|
||
|
|
||
|
## Getting Started
|
||
|
|
||
|
This is a quick walk-through of how to get started with the Google APIs for Go.
|
||
|
|
||
|
## Background
|
||
|
|
||
|
The first thing to understand is that the Google API libraries are auto-generated for
|
||
|
each language, including Go, so they may not feel like 100% natural for any language.
|
||
|
The Go versions are pretty natural, but please forgive any small non-idiomatic things.
|
||
|
(Suggestions welcome, though!)
|
||
|
|
||
|
## Installing
|
||
|
|
||
|
Pick an API and a version of that API to install.
|
||
|
You can find the complete list by looking at the
|
||
|
[directories here](https://github.com/google/google-api-go-client/tree/master/).
|
||
|
|
||
|
For example, let's install the
|
||
|
[urlshortener's version 1 API](https://godoc.org/google.golang.org/api/urlshortener/v1):
|
||
|
|
||
|
```
|
||
|
$ go get -u google.golang.org/api/urlshortener/v1
|
||
|
```
|
||
|
|
||
|
Now it's ready for use in your code.
|
||
|
|
||
|
## Using
|
||
|
|
||
|
Once you've installed a library, you import it like this:
|
||
|
|
||
|
```go
|
||
|
package main
|
||
|
|
||
|
import (
|
||
|
"golang.org/x/net/context"
|
||
|
"golang.org/x/oauth2"
|
||
|
"golang.org/x/oauth2/google"
|
||
|
"google.golang.org/api/urlshortener/v1"
|
||
|
)
|
||
|
```
|
||
|
|
||
|
The package name, if you don't override it on your import line, is the name of the
|
||
|
API without the version number. In the case above, just `urlshortener`.
|
||
|
|
||
|
## Instantiating
|
||
|
|
||
|
Each API has a `New` function taking an `*http.Client` and returning an API-specific `*Service`.
|
||
|
|
||
|
You create the service like:
|
||
|
|
||
|
```go
|
||
|
svc, err := urlshortener.New(httpClient)
|
||
|
```
|
||
|
|
||
|
## OAuth HTTP Client
|
||
|
|
||
|
The HTTP client you pass in to the service must be one that automatically adds
|
||
|
Google-supported Authorization information to the requests.
|
||
|
|
||
|
There are several ways to do authentication. They will all involve the package
|
||
|
[golang.org/x/oauth2](https://godoc.org/golang.org/x/oauth2) in some way.
|
||
|
|
||
|
### 3-legged OAuth
|
||
|
|
||
|
For 3-legged OAuth (your application redirecting a user through a website to get a
|
||
|
token giving your application access to that user's resources), you will need to
|
||
|
create an oauth2.Config,
|
||
|
|
||
|
|
||
|
```go
|
||
|
var config = &oauth2.Config{
|
||
|
ClientID: "", // from https://console.developers.google.com/project/<your-project-id>/apiui/credential
|
||
|
ClientSecret: "", // from https://console.developers.google.com/project/<your-project-id>/apiui/credential
|
||
|
Endpoint: google.Endpoint,
|
||
|
Scopes: []string{urlshortener.UrlshortenerScope},
|
||
|
}
|
||
|
```
|
||
|
|
||
|
... and then use the AuthCodeURL, Exchange, and Client methods on it.
|
||
|
For an example, see: https://godoc.org/golang.org/x/oauth2#example-Config
|
||
|
|
||
|
For the redirect URL, see
|
||
|
https://developers.google.com/identity/protocols/OAuth2InstalledApp#choosingredirecturi
|
||
|
|
||
|
### Service Accounts
|
||
|
|
||
|
To use a Google service account, or the GCE metadata service, see
|
||
|
the [golang.org/x/oauth2/google](https://godoc.org/golang.org/x/oauth2/google) package.
|
||
|
In particular, see [google.DefaultClient](https://godoc.org/golang.org/x/oauth2/google#DefaultClient).
|
||
|
|
||
|
### Using API Keys
|
||
|
|
||
|
Some APIs require passing API keys from your application.
|
||
|
To do this, you can use
|
||
|
[transport.APIKey](https://godoc.org/google.golang.org/api/googleapi/transport#APIKey):
|
||
|
|
||
|
```go
|
||
|
ctx := context.WithValue(context.Background(), oauth2.HTTPClient, &http.Client{
|
||
|
Transport: &transport.APIKey{Key: developerKey},
|
||
|
})
|
||
|
oauthConfig := &oauth2.Config{ .... }
|
||
|
var token *oauth2.Token = .... // via cache, or oauthConfig.Exchange
|
||
|
httpClient := oauthConfig.Client(ctx, token)
|
||
|
svc, err := urlshortener.New(httpClient)
|
||
|
...
|
||
|
```
|
||
|
|
||
|
## Using the Service
|
||
|
|
||
|
Each service contains zero or more methods and zero or more sub-services.
|
||
|
The sub-services related to a specific type of "Resource".
|
||
|
|
||
|
Those sub-services then contain their own methods.
|
||
|
|
||
|
For instance, the urlshortener API has just the "Url" sub-service:
|
||
|
|
||
|
```go
|
||
|
url, err := svc.Url.Get(shortURL).Do()
|
||
|
if err != nil {
|
||
|
...
|
||
|
}
|
||
|
fmt.Printf("The URL %s goes to %s\n", shortURL, url.LongUrl)
|
||
|
```
|
||
|
|
||
|
For a more complete example, see
|
||
|
[urlshortener.go](https://github.com/google/google-api-go-client/tree/master/examples/urlshortener.go)
|
||
|
in the [examples directory](https://github.com/google/google-api-go-client/tree/master/examples/).
|
||
|
(the examples use some functions in `main.go` in the same directory)
|