(Excel) OneDrive -- Streaming REST Download to File

Downloads the contents of a DriveItem directly to a file in the local filesystem using the Chilkat REST class.

Note: This example requires Chilkat v9.5.0.69 or greater.

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' This example requires the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.

Dim rest As Chilkat.Rest
Set rest = Chilkat.NewRest

' Use your previously obtained access token here:
' See the following examples for getting an access token:
'    Get Microsoft Graph OAuth2 Access Token (Azure AD v2.0 Endpoint).
'    Get Microsoft Graph OAuth2 Access Token (Azure AD Endpoint).
'    Refresh Access Token (Azure AD v2.0 Endpoint).
'    Refresh Access Token (Azure AD Endpoint).

' First connect to graph.microsoft.com.  If there's a connectivity problem, we'll find out here.

success = rest.Connect("graph.microsoft.com",443,True,True)
If (success <> True) Then
    Debug.Print rest.LastErrorText
    Exit Sub
End If

' (Make sure your token was obtained with the FilesRead or Files.ReadWrite scope.)
Dim oauth2 As Chilkat.OAuth2
Set oauth2 = Chilkat.NewOAuth2
oauth2.AccessToken = "MICROSOFT_GRAPH_ACCESS_TOKEN"
Dim success As Boolean
success = rest.SetAuthOAuth2(oauth2)

' Send the GET request to download the file.

uriPath = "/v1.0/me/drive/root:/Misc/wildlife/penguins.jpg:/content"
success = rest.SendReqNoBody("GET",uriPath)
If (rest.LastMethodSuccess <> True) Then
    Debug.Print rest.LastErrorText
    Exit Sub
End If

' NOTE: This way of doing the HTTP GET (i.e. download) may be more cumbersome, but it 
' allows for finer control of handling errors.  The connection establishment, the sending of the
' request, the reading of the response header, and the reading of the response body (i.e. the file data)
' are handled by separate method calls.  If the response header indicates an error, we can read
' the response body and treat it differently than if reading the file data.

' Read the response header.

statusCode = rest.ReadResponseHeader()
Debug.Print "Response Status Code = "; statusCode
If (statusCode = 302) Then
    ' This is a redirect.  Read the response body, if any, and then follow the redirect.
    ' Usually the response body will be empty for a redirect, but we need to be sure to read
    ' the response body just in case it exists.
    Dim discard As Chilkat.BinData
    Set discard = Chilkat.NewBinData
    success = rest.ReadRespBd(discard)
    success = rest.Disconnect(10)

    ' For OneDrive, the redirect URL does not need authorization because the only way
    ' to have obtained the direct download URL is from an authenticated request.
    ' In fact, if we leave the authentication present, the GET request to the redirect URL will fail.

    ' Note: The ClearAuth method is introduced in v9.5.0.69.
    success = rest.ClearAuth()

    ' Follow the redirect URL...

    Set redirectUrl = rest.RedirectUrl()
    Debug.Print "Redirect Host: "; redirectUrl.Host
    Debug.Print "Redirect URI Path: "; redirectUrl.PathWithQueryParams

    success = rest.Connect(redirectUrl.Host,redirectUrl.Port,redirectUrl.Ssl,True)
    If (success <> True) Then
        Debug.Print rest.LastErrorText
        Exit Sub
    End If

    ' Send the request..
    success = rest.SendReqNoBody("GET",redirectUrl.Path)

    If (rest.LastMethodSuccess <> True) Then
        Debug.Print rest.LastErrorText
        Exit Sub
    End If

    statusCode = rest.ReadResponseHeader()
    Debug.Print rest.LastErrorText
    Debug.Print "Redirect Response Status Code = "; statusCode

End If

If (statusCode >= 300) Then

    ' Read the error response body.
    Dim sbJson As Chilkat.StringBuilder
    Set sbJson = Chilkat.NewStringBuilder
    success = rest.ReadRespSb(sbJson)
    If (success <> True) Then
        Debug.Print rest.LastErrorText
        Exit Sub
    End If

    Dim jsonErr As Chilkat.JsonObject
    Set jsonErr = Chilkat.NewJsonObject
    jsonErr.EmitCompact = False
    success = jsonErr.LoadSb(sbJson)
    Debug.Print jsonErr.Emit()

    Exit Sub
End If

' Stream the response body directly to a local file.

localPath = "qa_output/penguins.jpg"

Dim stream As Chilkat.Stream
Set stream = Chilkat.NewStream
stream.SinkFile = localPath

success = rest.ReadRespBodyStream(stream,True)
If (success <> True) Then
    Debug.Print rest.LastErrorText
    Exit Sub
End If

Debug.Print "Successfully streamed a OneDrive file to the local filesystem."