(C# UWP/WinRT) 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.

Chilkat Universal Windows Platform (UWP) / WinRT Downloads Chilkat for the Universal Windows Platform (UWP)

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

Chilkat.Rest rest = new Chilkat.Rest();

// 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.
bool success = await rest.ConnectAsync("graph.microsoft.com",443,true,true);
if (success != true) {
    Debug.WriteLine(rest.LastErrorText);
    return;
}

// (Make sure your token was obtained with the FilesRead or Files.ReadWrite scope.)
Chilkat.OAuth2 oauth2 = new Chilkat.OAuth2();
oauth2.AccessToken = "MICROSOFT_GRAPH_ACCESS_TOKEN";
rest.SetAuthOAuth2(oauth2);

// Send the GET request to download the file.
string uriPath = "/v1.0/me/drive/root:/Misc/wildlife/penguins.jpg:/content";
success = await rest.SendReqNoBodyAsync("GET",uriPath);
if (rest.LastMethodSuccess != true) {
    Debug.WriteLine(rest.LastErrorText);
    return;
}

// 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.
int statusCode = await rest.ReadResponseHeaderAsync();
Debug.WriteLine("Response Status Code = " + Convert.ToString(statusCode));
if (statusCode == 302) {
    // 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.
    Chilkat.BinData discard = new Chilkat.BinData();
    await rest.ReadRespBdAsync(discard);
    await rest.DisconnectAsync(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.
    rest.ClearAuth();

    // Follow the redirect URL...
    Chilkat.Url redirectUrl = rest.RedirectUrl();
    Debug.WriteLine("Redirect Host: " + redirectUrl.Host);
    Debug.WriteLine("Redirect URI Path: " + redirectUrl.PathWithQueryParams);

    success = await rest.ConnectAsync(redirectUrl.Host,redirectUrl.Port,redirectUrl.Ssl,true);
    if (success != true) {
        Debug.WriteLine(rest.LastErrorText);
        return;
    }

    // Send the request..
    success = await rest.SendReqNoBodyAsync("GET",redirectUrl.Path);

    if (rest.LastMethodSuccess != true) {
        Debug.WriteLine(rest.LastErrorText);
        return;
    }

    statusCode = await rest.ReadResponseHeaderAsync();
    Debug.WriteLine(rest.LastErrorText);
    Debug.WriteLine("Redirect Response Status Code = " + Convert.ToString(statusCode));

}

if (statusCode >= 300) {

    // Read the error response body.
    Chilkat.StringBuilder sbJson = new Chilkat.StringBuilder();
    success = await rest.ReadRespSbAsync(sbJson);
    if (success != true) {
        Debug.WriteLine(rest.LastErrorText);
        return;
    }

    Chilkat.JsonObject jsonErr = new Chilkat.JsonObject();
    jsonErr.EmitCompact = false;
    jsonErr.LoadSb(sbJson);
    Debug.WriteLine(jsonErr.Emit());

    return;
}

// Stream the response body directly to a local file.
string localPath = "qa_output/penguins.jpg";

Chilkat.Stream stream = new Chilkat.Stream();
stream.SinkFile = localPath;

success = await rest.ReadRespBodyStreamAsync(stream,true);
if (success != true) {
    Debug.WriteLine(rest.LastErrorText);
    return;
}

Debug.WriteLine("Successfully streamed a OneDrive file to the local filesystem.");