[Question] How to get OBO token from an event handler

How can I get an OBO access token in an event handler like:

[HttpPost]
public IActionResult ProcessData(string data)
{
    var processor = new Processor();

    processor.Finished += async (s, e) =>
    {
        var accessToken = await this
            ._tokenAcquisition
            .GetAccessTokenForUserAsync(new[] { "Files.ReadWrite" }, user: this.User);

        await WriteToOneDrive(accessToken, e.Data);
    };

    processor.processAsync(data); // Run async without awaiting

    return NoContent();
}

In this case the this.User is already disposed, and even without it, GetAccessTokenForUserAsync crashes with NullObjectException.

My process takes a very long time (hours).

How can I get the token inside a callback when I need it?

[jmprieur]

I think that the problem is that the HttpContext is null, or HttpContext.Items is null:

https://github.com/AzureAD/microsoft-identity-web/blob/41195539af65836b464b063c186842896ab15e0e/src/Microsoft.Identity.Web/HttpContextExtensions.cs#L30

We should probably guard against these cases:

 return httpContext?.Items?[Constants.JwtSecurityTokenUsedToCallWebApi] as JwtSecurityToken;

as if the token is returned null, the AcquireTokenSilent will be tried, which should work for this scenario.

@jennyf19 @pmaytak @henrik-me I’m tempted to take this in 0.3.0-preview if you don’t mind, as this would unblock our partner.

[hrazmsft]

Hi @jennyf19 I still can’t get a token inside a callback with the latest master (error below).

I’ve open a repo with sample code with repro of the problem here