(Go) Download GMail Message Attachment by ID

Demonstrates how to download a GMail email attachment by the attachment ID.

For more information, see https://developers.google.com/gmail/api/v1/reference/users/messages/attachments/get

Chilkat Go Downloads Go Package for Windows, MacOS, Linux, Alpine Linux, Solaris

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

    http := chilkat.NewHttp()
    var success bool

    http.SetAuthToken("ACCESS_TOKEN")
    http.SetAccept("application/json")

    // See the following example:  Get GMail Message (format=full)
    // It shows how to download an email by message ID, and it shows how to parse the JSON
    // response which includes attachment names, ids, and other information.

    // This example will assume we already have the attachment id and filename.

    // This is the attachment ID for a file named "helloWorld.pdf".
    attachmentId := "ANGjdJ-oy3aCuZISJKLAhUdaEksCEklbAPyMaWzFgqOMGbPCRkgwgeu_Kttd99C17OBTHROkDZGekibTKWXGfscB5ww7fw4E65_V1dQ-jHhb2TD1Cdm58-BbNw2iDxzptco8iILPiSnLLfFn5Ps7nsRcxHaGTt3r0yqFKCuIYNnPK1vM04BXI_cfzo-HnI4I3tD6oHNHOGVQrL01MdShFQjPELPUjXM8z1qs7Kom-QyvV1iOldUN-66UuhynsmDX-CMM5TIdB-8KD_lmdhf-0DqG8JnCA20XpXyfqwS8XFkPA-t-QSjb7SdkHQFtQ4lz2PcBREFzZ2eI5j0l0Y_dQHRPYTeMwkVl1yl4MfFT4C4iso3VSF-eqaIjiFCbXKCFNyeEIW5WFsv189dhlSqU"

    messageId := "1712bc1dc22da2a2"

    http.SetUrlVar("messageId",messageId)
    http.SetUrlVar("attachmentId",attachmentId)

    url := "https://www.googleapis.com/gmail/v1/users/userId/messages/{$messageId}/attachments/{$attachmentId}"

    // When we download, the response is JSON that contains the attachment data base64url encoded, like this:
    // {
    //  "size": 934,
    //  "data": "JVBERi0xLjM ... CiUlRU9GCg=="
    // }

    outputFilePath := "qa_output/helloWorld.pdf"

    // Download into a StringBuilder.
    sbJson := chilkat.NewStringBuilder()
    success = http.DownloadSb(url,"utf-8",sbJson)
    if success == false {
        fmt.Println(http.LastErrorText())
        http.DisposeHttp()
        sbJson.DisposeStringBuilder()
        return
    }

    if http.LastStatus() != 200 {
        // Something failed.
        // the JSON contains an error message.
        fmt.Println(*sbJson.GetAsString())
        http.DisposeHttp()
        sbJson.DisposeStringBuilder()
        return
    }

    // Load into a Chilkat JSON object.
    json := chilkat.NewJsonObject()
    success = json.LoadSb(sbJson)

    // Extract the base64url data into a BinData.
    bd := chilkat.NewBinData()
    success = json.BytesOf("data","base64url",bd)

    // Save the data to a file.
    success = bd.WriteFile("qa_output/helloWorld.pdf")

    fmt.Println("Success.")

    http.DisposeHttp()
    sbJson.DisposeStringBuilder()
    json.DisposeJsonObject()
    bd.DisposeBinData()