Go

Download Object from Google Cloud Storage

See more Google Cloud Storage Examples

Demonstrates how to download an object from Google Cloud Storage to a file. Go

    success := false

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // This example uses a previously obtained access token having permission for the 
    // scope "https://www.googleapis.com/auth/cloud-platform"

    // In this example, Get Google Cloud Storage OAuth2 Access Token, 
    // the service account access token was saved to a text file.  This example fetches the access token from the file..
    sbToken := chilkat.NewStringBuilder()
    sbToken.LoadFile("qa_data/tokens/googleCloudStorageAccessToken.txt","utf-8")

    // Send a GET equivalent to this curl command.

    // curl -X GET \
    //     -H "Authorization: Bearer [OAUTH2_TOKEN]" \
    //     -o "[SAVE_TO_LOCATION]" \
    //     "https://www.googleapis.com/storage/v1/b/[BUCKET_NAME]/o/[OBJECT_NAME]?alt=media"

    http := chilkat.NewHttp()

    http.SetAuthToken(sbToken.GetAsString())

    // Construct a URL to download an object named "starfish.jpg" from the "chilkat-ocean" bucket.
    http.SetUrlVar("bucket_name","chilkat-ocean")
    http.SetUrlVar("object_name","starfish.jpg")
    url := "https://www.googleapis.com/storage/v1/b/{$bucket_name}/o/{$object_name}?alt=media"

    // If there is an error response, then we didn't actually download the file data,
    // but instead we downloaded an error response..
    fileData := chilkat.NewBinData()
    success = http.DownloadBd(url,fileData)
    if success == false {
        fmt.Println(http.LastErrorText())
        sbToken.DisposeStringBuilder()
        http.DisposeHttp()
        fileData.DisposeBinData()
        return
    }

    sbErrorResponse := chilkat.NewStringBuilder()
    responseCode := http.LastStatus()
    if responseCode == 401 {
        fmt.Println("If invalid credentials, then it is likely the access token expired.")
        fmt.Println("Your app should automatically fetch a new access token and re-try.")
    }

    if responseCode != 200 {
        // Get the error response
        sbErrorResponse.AppendBd(fileData,"utf-8",0,0)
        fmt.Println("Error response code = ", responseCode)
        fmt.Println("Error:")
        fmt.Println(*sbErrorResponse.GetAsString())
        sbToken.DisposeStringBuilder()
        http.DisposeHttp()
        fileData.DisposeBinData()
        sbErrorResponse.DisposeStringBuilder()
        return
    }

    fmt.Println("Success.")

    // Save the downloaded data to a file.
    success = fileData.WriteFile("qa_output/starfish.jpg")

    sbToken.DisposeStringBuilder()
    http.DisposeHttp()
    fileData.DisposeBinData()
    sbErrorResponse.DisposeStringBuilder()