Jalpa's answer was not what I was looking for, nor was anything referenced in any of the links.
I'm going to put my answer here, because it is what I needed, and it might be useful to others.
First the overview
Google's QuickStart for .NET only shows the console based solution. As many have discovered, this does not work when you switch to an IIS based solution. It is almost as if the API deliberately defeats your attempts to do so. It simply will not allow you to use a token created for a local application using GoogleWebAuthorizationBroker.AuthorizeAsync -- it will error even if a browser isn't needed. (ie the token hasn't expired, so it won't need the browser to authenticate anything.)
Trying to run a refresh authorization gives you a token, but not a service. And even if the token is valid, you still can't use AuthorizeAsync to get your service from an IIS application (see above)
This is how I handle this:
- Do the quick start and run the authorization that pops up the local browser and allows you to login and authenticate.
- It creates a local folder(token.json), where it puts a token file (Google.Apis.Auth.OAuth2.Responses.TokenResponse-user) It's just a json file. Open it in notepad++ and you will find the fields:
- "access_token": "token_type": "expires_in": "refresh_token":
"scope": "Issued": "IssuedUtc":
You need the refresh_token. I simply combined that with the initial credentials file I downloaded from the Google API Console (i.e. "credentials.json") and named it "skeleton_key.json"
This file is all you will need to generate valid tokens forever.
I have 2 classes I use for this. First the class that creates the Drive Service:
public class GDriveClass
{
public String LastErrorMessage { get; set; }
static string[] Scopes = { DriveService.Scope.Drive }; // could pull this from skeleton_key
static string ApplicationName = "GDrive Access"; // this is functionally irrelevant
internal UserCredential usrCredentials;
internal Google.Apis.Drive.v3.DriveService CurrentGDriveService = null;
internal String basePath = "."; // this comes in from calling program
// which uses HttpContext.Current.Server.MapPath("~");
public GDriveClass(string logFileBasePath)
{
basePath = logFileBasePath;
LastErrorMessage = "";
}
#region Google Drive Authenticate Code
public bool AuthenticateUser(string FullTokenAccessFileName)
{
UserCredential credential;
String JsonCredentialsonFile = System.IO.File.ReadAllText(FullTokenAccessFileName);
string credPath = basePath + @"\Credentials\token.json";
// Force a Refresh of the Token
RefreshTokenClass RTC = new RefreshTokenClass();
// Set field values in RefreshTokenClass:
var jObject = Newtonsoft.Json.Linq.JObject.Parse(JsonCredentialsonFile);
var fieldStrings = jObject.GetValue("installed").ToString();
var fields = Newtonsoft.Json.Linq.JObject.Parse(fieldStrings);
RTC.client_id = fields.GetValue("client_id").ToString();
RTC.client_secret = fields.GetValue("client_secret").ToString();
RTC.refresh_token = fields.GetValue("refresh_token").ToString();
RTC.ExecuteRefresh(); // this gets us a valid token every time
try
{
GoogleCredential gCredentials = GoogleCredential.FromAccessToken(RTC.access_token);
CurrentGDriveService = new DriveService(new BaseClientService.Initializer()
{
HttpClientInitializer = gCredentials,
ApplicationName = ApplicationName,
});
return true;
}
catch (Exception ex)
{
LastErrorMessage = "Error: Authenticating - " + ex.Message;
return false;
}
}
Usage is pretty straight forward:
string TokenFile = @basePath + @"\skeleton_key.json";
GDRIVER.AuthenticateUser(TokenFile);
var rslt = GDRIVER.LastErrorMessage;
if (!String.IsNullOrEmpty(rslt))
{
WriteToLogFile("ERROR in Google AuthenticateUser() ");
AlertMessage("Unable To Connect to Google Drive - Authorization Failed");
return;
}
And this is the class that refreshes the token via REST API as needed:
public class RefreshTokenClass
{
public string application_name { get; set; }
public string token_source { get; set; }
public string client_id { get; set; }
public string client_secret { get; set; }
public string scope { get; set; }
public string access_token { get; set; }
public string refresh_token { get; set; }
public RefreshTokenClass()
{
}
public bool ExecuteRefresh()
{
try
{
RestClient restClient = new RestClient();
RestRequest request = new RestRequest();
request.AddQueryParameter("client_id", this.client_id);
request.AddQueryParameter("client_secret", this.client_secret);
request.AddQueryParameter("grant_type", "refresh_token");
request.AddQueryParameter("refresh_token", this.refresh_token);
restClient.BaseUrl = new System.Uri("https://oauth2.googleapis.com/token");
var restResponse = restClient.Post(request);
// Extracting output data from received response
string response = restResponse.Content.ToLower(); // make sure case isn't an issue
// Parsing JSON content into element-node JObject
var jObject = Newtonsoft.Json.Linq.JObject.Parse(restResponse.Content);
//Extracting Node element using Getvalue method
string _access_token = jObject.GetValue("access_token").ToString();
this.access_token = _access_token;
return true;
}
catch (Exception ex)
{
//Console.WriteLine("Error on Token Refresh" + ex.Message);
return false;
}
}
Note: This makes use of Newtonsoft.Json and RestSharp.
Thanks to user: "OL." who gave me the way of creating a service from a token (that somehow I missed in the docs!)
How to create Service from Access Token
And to user:"purshotam sah" for a clean REST API approach
Generate Access Token Using Refresh Token
