Xbase++

Download File (Stream to Local Filesystem)

See more Google Drive Examples

This example demonstrates how to download the content of a file from Google Drive. The file is streamed to the local filesystem. Xbase++

LOCAL nSuccess
LOCAL oGAuth
LOCAL oRest
LOCAL nBAutoReconnect
LOCAL oGdCache
LOCAL cFileId
LOCAL oSbPath
LOCAL oFileStream
LOCAL cJsonResponse

nSuccess := 0

nSuccess := 1

//  It 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 
//  Google Drive scope.

oGAuth := CreateObject("Chilkat.AuthGoogle")
oGAuth:AccessToken := "GOOGLE_DRIVE_ACCESS_TOKEN"

oRest := CreateObject("Chilkat.Rest")

//  Connect using TLS.
//  A single REST object, once connected, can be used for many Google Drive REST API calls.
//  The auto-reconnect indicates that if the already-established HTTPS connection is closed,
//  then it will be automatically re-established as needed.
nBAutoReconnect := 1
nSuccess := oRest:Connect("www.googleapis.com", 443, 1, nBAutoReconnect)

//  Provide the authentication credentials (i.e. the access token)
oRest:SetAuthGoogle(oGAuth)

//  ------------------------------------------------------------------------------
//  To download a file, we must know the file ID.
//  In a previous example (see Build Local Metadata Cache
//  we built a local cache to make it easy to lookup file IDs given a file path.
//  Let's say we want to download "testFolder/abc/123/penguins.jpg".
//  First we lookup the fileId in the cache.  With the fileId, we can download the file.
oGdCache := CreateObject("Chilkat.Cache")
oGdCache:Level := 0
oGdCache:AddRoot("C:/ckCache/googleDrive")

cFileId := oGdCache:FetchText("testFolder/abc/123/penguins.jpg")
IF (oGdCache:LastMethodSuccess != 1)
    ? "Filepath not found in cache."
    oGAuth:destroy()
    oRest:destroy()
    oGdCache:destroy()
    RETURN
ENDIF

//  We need to send a GET request like this:
//  GET https://www.googleapis.com/drive/v3/files/fileId?alt=media
//  The fileId is part of the path.
oSbPath := CreateObject("Chilkat.StringBuilder")
oSbPath:Append("/drive/v3/files/")
oSbPath:Append(cFileId)
oRest:AddQueryParam("alt", "media")

//  Create a stream object with a SinkFile set to the path where the downloaded file will go.
oFileStream := CreateObject("Chilkat.Stream")
oFileStream:SinkFile := "qa_output/penguins.jpg"
//  Indicate that the response body should stream directly to fileStream,
//  but only if the response status is 200.  
oRest:SetResponseBodyStream(200, 1, oFileStream)

//  Download the file, streaming the content to the SinkFile.
cJsonResponse := oRest:FullRequestNoBody("GET", oSbPath:GetAsString())
IF (oRest:LastMethodSuccess != 1)
    ? oRest:LastErrorText
    oGAuth:destroy()
    oRest:destroy()
    oGdCache:destroy()
    oSbPath:destroy()
    oFileStream:destroy()
    RETURN
ENDIF

//  A successful response will have a status code equal to 200.
IF (oRest:ResponseStatusCode != 200)
    ? "response status code = " + Str(oRest:ResponseStatusCode)
    ? "response status text = " + oRest:ResponseStatusText
    ? "response header: " + oRest:ResponseHeader
    oGAuth:destroy()
    oRest:destroy()
    oGdCache:destroy()
    oSbPath:destroy()
    oFileStream:destroy()
    RETURN
ENDIF

? "File downloaded."

oGAuth:destroy()
oRest:destroy()
oGdCache:destroy()
oSbPath:destroy()
oFileStream:destroy()