B4X

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. B4X

Dim success As Boolean = False

success = True

'  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.

Dim gAuth As ChilkatAuthGoogle
gAuth.Initialize("gAuth")
gAuth.AccessToken = "GOOGLE_DRIVE_ACCESS_TOKEN"

Dim rest As ChilkatRest
rest.Initialize("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.
Dim bAutoReconnect As Boolean = True
success = rest.Connect("www.googleapis.com", 443, True, bAutoReconnect)

'  Provide the authentication credentials (i.e. the access token)
rest.SetAuthGoogle(gAuth)

'  ------------------------------------------------------------------------------
'  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.
Dim gdCache As ChilkatCache
gdCache.Initialize
gdCache.Level = 0
gdCache.AddRoot("C:/ckCache/googleDrive")

Dim fileId As String = gdCache.FetchText("testFolder/abc/123/penguins.jpg")
If gdCache.LastMethodSuccess <> True Then
    Log("Filepath not found in cache.")
    Return
End If


'  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.
Dim sbPath As ChilkatStringBuilder
sbPath.Initialize
sbPath.Append("/drive/v3/files/")
sbPath.Append(fileId)
rest.AddQueryParam("alt", "media")

'  Create a stream object with a SinkFile set to the path where the downloaded file will go.
Dim fileStream As ChilkatStream
fileStream.Initialize("fileStream")
fileStream.SinkFile = "qa_output/penguins.jpg"
'  Indicate that the response body should stream directly to fileStream,
'  but only if the response status is 200.  
rest.SetResponseBodyStream(200, True, fileStream)

'  Download the file, streaming the content to the SinkFile.
Dim jsonResponse As String = rest.FullRequestNoBody("GET", sbPath.GetAsString)
If rest.LastMethodSuccess <> True Then
    Log(rest.LastErrorText)
    Return
End If


'  A successful response will have a status code equal to 200.
If rest.ResponseStatusCode <> 200 Then
    Log("response status code = " & rest.ResponseStatusCode)
    Log("response status text = " & rest.ResponseStatusText)
    Log("response header: " & rest.ResponseHeader)
    Return
End If


Log("File downloaded.")