B4X

Download Binary File to In-Memory Bytes

See more Google Drive Examples

This example demonstrates how to download the binary content of a file from Google Drive directly into local memory. 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")

'  To download to memory, we'll send the request in one call, then receive
'  the response header, and then the response body.
'  If the response header indicates failure or an unexpected response, then the
'  body is not the data we desire.

'  First send the HTTP request.
success = rest.SendReqNoBody("GET", sbPath.GetAsString)
If success <> True Then
    Log(rest.LastErrorText)
    Return
End If


'  Get the response header.
Dim statusCode As Int = rest.ReadResponseHeader
If statusCode <> 200 Then
    Log("response status code = " & rest.ResponseStatusCode)
    Log("response status text = " & rest.ResponseStatusText)
    Log("response header: " & rest.ResponseHeader)

    '  Read the response body (which should be error text or HTML)
    Dim errResponseBody As String = rest.ReadRespBodyString
    If rest.LastMethodSuccess = True Then
        Log("response body: " & errResponseBody)
    End If

    Return
End If


'  Read the response body, which should contain the file data.

jpgBytes = rest.ReadRespBodyBinary
If rest.LastMethodSuccess <> True Then
    Log(rest.LastErrorText)
    Return
End If


'  Save jpgBytes to a file so we can examine the file to verify that it worked.
Dim fac As ChilkatFileAccess
fac.Initialize
fac.WriteEntireFile("qa_output/penguins_out.jpg", jpgBytes)

Log("File downloaded.")