Mapping a custom JSON into ClaimActions - oauth-2.0

Question

I am developing a Angular based website in which a user is required to login using a custom OAuth2 third party authentication provider. .Net core web API is the backend. The response received from the user end point is in JSON and it is having the following format:
{
"dataSources": {
"profile": {
"username": "xyz"
}
},
"profile": {
"id": "87dfkajdfd998df"
},
"errors": {}
}
The code I am currently using is as follows:
builder.AddOAuth(oauth2Configuration.Issuer,
options => {
options.ClientId = oauth2Configuration.ClientId;
options.ClientSecret = oauth2Configuration.ClientSecret;
options.Scope.Add(oauth2Configuration.Scope);
options.ClaimsIssuer = oauth2Configuration.Issuer;
options.CallbackPath = new PathString(oauth2Configuration.ResponseType);
options.AuthorizationEndpoint = oauth2Configuration.Authority;
options.TokenEndpoint = oauth2Configuration.EndSessionEndpoint;
options.UserInformationEndpoint = oauth2Configuration.UserInfoEndpoint;
options.SaveTokens = true;
// Below mapping does not seem to work
options.ClaimActions.MapJsonSubKey(ClaimTypes.Name, "dataSources", "profile.username");
options.ClaimActions.MapJsonKey(ClaimTypes.SerialNumber, "profile.id");
// Remaining code
})
After authenticating with the above code, the claims list is always empty.
Has anyone encountered a similar situation in which claim mapping was done for custom JSON data?

Answer 1

That seems the OAuth authentication handler itself won't help call the endpoint , you need to manually make a call to obtain use's profile from UserInfo endpoint in OnCreatingTicket event :
OnCreatingTicket = async context =>
{
var request = new HttpRequestMessage(HttpMethod.Get, context.Options.UserInformationEndpoint);
request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", context.AccessToken);
var response = await context.Backchannel.SendAsync(request, HttpCompletionOption.ResponseHeadersRead, context.HttpContext.RequestAborted);
response.EnsureSuccessStatusCode();
var user = JObject.Parse(await response.Content.ReadAsStringAsync());
context.RunClaimActions(user);
}
And make claim mapping manually based on your scenario - parse/read the json using JSON.NET and add to user's princple . Please refer to below articles for code samples :
https://www.jerriepelser.com/blog/authenticate-oauth-aspnet-core-2/
https://stackoverflow.com/a/46064936/5751404