(Visual Basic 6.0) Download Binary File to In-Memory Bytes

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

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

Dim success As Long
success = 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.

Dim gAuth As New ChilkatAuthGoogle
gAuth.AccessToken = "GOOGLE-DRIVE-ACCESS-TOKEN"

Dim rest As New ChilkatRest

' 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 Long
bAutoReconnect = 1
success = rest.Connect("www.googleapis.com",443,1,bAutoReconnect)

' Provide the authentication credentials (i.e. the access token)
success = 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 New ChilkatCache
gdCache.Level = 0
gdCache.AddRoot "C:/ckCache/googleDrive"

Dim fileId As String
fileId = gdCache.FetchText("testFolder/abc/123/penguins.jpg")
If (gdCache.LastMethodSuccess <> 1) Then
    Debug.Print "Filepath not found in cache."
    Exit Sub
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 New ChilkatStringBuilder
success = sbPath.Append("/drive/v3/files/")
success = sbPath.Append(fileId)
success = 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 <> 1) Then
    Debug.Print rest.LastErrorText
    Exit Sub
End If

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

    ' Read the response body (which should be error text or HTML)
    Dim errResponseBody As String
    errResponseBody = rest.ReadRespBodyString()
    If (rest.LastMethodSuccess = 1) Then
        Debug.Print "response body: " & errResponseBody
    End If

    Exit Sub
End If

' Read the response body, which should contain the file data.
Dim jpgBytes() As Byte
jpgBytes = rest.ReadRespBodyBinary()
If (rest.LastMethodSuccess <> 1) Then
    Debug.Print rest.LastErrorText
    Exit Sub
End If

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

Debug.Print "File downloaded."