Custom AuthorizeAttribute OnAuthorizationAsync Function

Question

I'm trying to make my own custom System.Web.Http.AuthorizeAttribute. Everything was working until I needed to run some async function inside of the overridden OnAuthorizationfunction.

I found the OnAuthorizationAsync method and I use that, however still having issues running an async method. I need to ensure that a header attached to the HttpActionContext is in the db.

    public override Task OnAuthorizationAsync(HttpActionContext actionContext, CancellationToken cancellationToken)
    {
        IEnumerable<string> values;
        if (actionContext.Request.Headers.TryGetValues("Authentication", out values))
        {
            var token = new Token() { TokenString = values.First() };
            if (await _tg.ValidateToken(token))
            {
                return base.OnAuthorizationAsync(actionContext, cancellationToken);
            }
        }

        base.HandleUnauthorizedRequest(actionContext);
    }

_tg.ValidateToken(token) is an async method that returns a bool. If I try to await it and make OnAuthorizationAsync an async method I then apparently cant return a Task:

Since OnAuthorizeAsync is an async method that returns 'Task', a return keyword must not be followed by an object expression.

Is there a way you can see out of this mess?

sellotape · Accepted Answer · 2016-12-03 07:45:25Z

4

Because you use await, you need to add the async modifier to the method's declaration. Then change the return you have there to await. The compiler will do the rest - i.e. returning the Task for you.

answered Dec 3, 2016 at 7:45

sellotape

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1 Comment

DanielV Over a year ago

@Nick H, should mark this answer as valid if it works for you

peterpie · Accepted Answer · 2023-04-18 08:46:00Z

2

Based on @sellotape's answer:

public async override Task OnAuthorizationAsync(HttpActionContext actionContext, CancellationToken cancellationToken)
{
    IEnumerable<string> values;
    if (actionContext.Request.Headers.TryGetValues("Authentication", out values))
    {
        var token = new Token() { TokenString = values.First() };
        if (await _tg.ValidateToken(token))
        {
            return await base.OnAuthorizationAsync(actionContext, cancellationToken);
        }
    }
    await base.HandleUnauthorizedRequest(actionContext);
}

edited Apr 18, 2023 at 8:46

peterpie

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answered Nov 13, 2018 at 13:20

DanielV

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1 Comment

JHBonarius Over a year ago

This is not complete. You need to await base.OnAuthorizationAsync, not return it. don't just pass the Task.

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