(Visual FoxPro) Download File (Stream to Local Filesystem)

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

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL lnSuccess
LOCAL loGAuth
LOCAL loRest
LOCAL lnBAutoReconnect
LOCAL loGdCache
LOCAL lcFileId
LOCAL loSbPath
LOCAL loFileStream
LOCAL lcJsonResponse

lnSuccess = 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.

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.AuthGoogle')
loGAuth = CreateObject('Chilkat.AuthGoogle')
loGAuth.AccessToken = "GOOGLE_DRIVE_ACCESS_TOKEN"

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Rest')
loRest = 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.
lnBAutoReconnect = 1
lnSuccess = loRest.Connect("www.googleapis.com",443,1,lnBAutoReconnect)

* Provide the authentication credentials (i.e. the access token)
loRest.SetAuthGoogle(loGAuth)

* ------------------------------------------------------------------------------
* 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.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Cache')
loGdCache = CreateObject('Chilkat.Cache')
loGdCache.Level = 0
loGdCache.AddRoot("C:/ckCache/googleDrive")

lcFileId = loGdCache.FetchText("testFolder/abc/123/penguins.jpg")
IF (loGdCache.LastMethodSuccess <> 1) THEN
    ? "Filepath not found in cache."
    RELEASE loGAuth
    RELEASE loRest
    RELEASE loGdCache
    CANCEL
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.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.StringBuilder')
loSbPath = CreateObject('Chilkat.StringBuilder')
loSbPath.Append("/drive/v3/files/")
loSbPath.Append(lcFileId)
loRest.AddQueryParam("alt","media")

* Create a stream object with a SinkFile set to the path where the downloaded file will go.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Stream')
loFileStream = CreateObject('Chilkat.Stream')
loFileStream.SinkFile = "qa_output/penguins.jpg"
* Indicate that the response body should stream directly to fileStream,
* but only if the response status is 200.  
loRest.SetResponseBodyStream(200,1,loFileStream)

* Download the file, streaming the content to the SinkFile.
lcJsonResponse = loRest.FullRequestNoBody("GET",loSbPath.GetAsString())
IF (loRest.LastMethodSuccess <> 1) THEN
    ? loRest.LastErrorText
    RELEASE loGAuth
    RELEASE loRest
    RELEASE loGdCache
    RELEASE loSbPath
    RELEASE loFileStream
    CANCEL
ENDIF

* A successful response will have a status code equal to 200.
IF (loRest.ResponseStatusCode <> 200) THEN
    ? "response status code = " + STR(loRest.ResponseStatusCode)
    ? "response status text = " + loRest.ResponseStatusText
    ? "response header: " + loRest.ResponseHeader
    RELEASE loGAuth
    RELEASE loRest
    RELEASE loGdCache
    RELEASE loSbPath
    RELEASE loFileStream
    CANCEL
ENDIF

? "File downloaded."

RELEASE loGAuth
RELEASE loRest
RELEASE loGdCache
RELEASE loSbPath
RELEASE loFileStream