(DataFlex) 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 ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

Use ChilkatAx-win32.pkg

Procedure Test
    Handle hoHttp
    Boolean iSuccess
    String sAttachmentId
    String sMessageId
    String sUrl
    String sOutputFilePath
    Variant vSbJson
    Handle hoSbJson
    Handle hoJson
    Variant vBd
    Handle hoBd
    String sTemp1
    Integer iTemp1

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

    Get Create (RefClass(cComChilkatHttp)) To hoHttp
    If (Not(IsComObjectCreated(hoHttp))) Begin
        Send CreateComObject of hoHttp
    End

    Set ComAuthToken Of hoHttp To "ACCESS_TOKEN"
    Set ComAccept Of hoHttp To "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".
    Move "ANGjdJ-oy3aCuZISJKLAhUdaEksCEklbAPyMaWzFgqOMGbPCRkgwgeu_Kttd99C17OBTHROkDZGekibTKWXGfscB5ww7fw4E65_V1dQ-jHhb2TD1Cdm58-BbNw2iDxzptco8iILPiSnLLfFn5Ps7nsRcxHaGTt3r0yqFKCuIYNnPK1vM04BXI_cfzo-HnI4I3tD6oHNHOGVQrL01MdShFQjPELPUjXM8z1qs7Kom-QyvV1iOldUN-66UuhynsmDX-CMM5TIdB-8KD_lmdhf-0DqG8JnCA20XpXyfqwS8XFkPA-t-QSjb7SdkHQFtQ4lz2PcBREFzZ2eI5j0l0Y_dQHRPYTeMwkVl1yl4MfFT4C4iso3VSF-eqaIjiFCbXKCFNyeEIW5WFsv189dhlSqU" To sAttachmentId

    Move "1712bc1dc22da2a2" To sMessageId

    Get ComSetUrlVar Of hoHttp "messageId" sMessageId To iSuccess
    Get ComSetUrlVar Of hoHttp "attachmentId" sAttachmentId To iSuccess

    Move "https://www.googleapis.com/gmail/v1/users/userId/messages/{$messageId}/attachments/{$attachmentId}" To sUrl

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

    Move "qa_output/helloWorld.pdf" To sOutputFilePath

    // Download into a StringBuilder.
    Get Create (RefClass(cComChilkatStringBuilder)) To hoSbJson
    If (Not(IsComObjectCreated(hoSbJson))) Begin
        Send CreateComObject of hoSbJson
    End
    Get pvComObject of hoSbJson to vSbJson
    Get ComDownloadSb Of hoHttp sUrl "utf-8" vSbJson To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoHttp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComLastStatus Of hoHttp To iTemp1
    If (iTemp1 <> 200) Begin
        // Something failed.
        // the JSON contains an error message.
        Get ComGetAsString Of hoSbJson To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Load into a Chilkat JSON object.
    Get Create (RefClass(cComChilkatJsonObject)) To hoJson
    If (Not(IsComObjectCreated(hoJson))) Begin
        Send CreateComObject of hoJson
    End
    Get pvComObject of hoSbJson to vSbJson
    Get ComLoadSb Of hoJson vSbJson To iSuccess

    // Extract the base64url data into a BinData.
    Get Create (RefClass(cComChilkatBinData)) To hoBd
    If (Not(IsComObjectCreated(hoBd))) Begin
        Send CreateComObject of hoBd
    End
    Get pvComObject of hoBd to vBd
    Get ComBytesOf Of hoJson "data" "base64url" vBd To iSuccess

    // Save the data to a file.
    Get ComWriteFile Of hoBd "qa_output/helloWorld.pdf" To iSuccess

    Showln "Success."


End_Procedure