(Ruby) 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 Ruby Downloads install from rubygems.org gem install chilkat or download... Ruby Library for Windows, MacOS, Linux, Alpine Linux

require 'chilkat'

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

http = Chilkat::CkHttp.new()

http.put_AuthToken("ACCESS_TOKEN")
http.put_Accept("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::CkStringBuilder.new()
success = http.DownloadSb(url,"utf-8",sbJson)
if (success == false)
    print http.lastErrorText() + "\n";
    exit
end

if (http.get_LastStatus() != 200)
    # Something failed.
    # the JSON contains an error message.
    print sbJson.getAsString() + "\n";
    exit
end

# Load into a Chilkat JSON object.
json = Chilkat::CkJsonObject.new()
success = json.LoadSb(sbJson)

# Extract the base64url data into a BinData.
bd = Chilkat::CkBinData.new()
success = json.BytesOf("data","base64url",bd)

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

print "Success." + "\n";