C#•3mo ago

ASP Core 8 - Custom 404 Handling

I have a few scenarios where I need to show a different kind of view and a bit of different logic depending on what type of authenticated user in my app experiences a "404" However, I don't understand how to capture the 404. I am using attribute routes and have the following middleware.

public class NotFoundMiddleware
{
    private readonly RequestDelegate RequestDelegate;

    public NotFoundMiddleware(RequestDelegate RequestDelegate)
    {
        this.RequestDelegate = RequestDelegate;
    }

    public async Task InvokeAsync(HttpContext context)
    {
        if (context.Response.StatusCode == StatusCodes.Status404NotFound)
        {
            context.Request.Path = "/client/errors/404";
        }

        await RequestDelegate(context);
    }
}

public class NotFoundMiddleware
{
    private readonly RequestDelegate RequestDelegate;

    public NotFoundMiddleware(RequestDelegate RequestDelegate)
    {
        this.RequestDelegate = RequestDelegate;
    }

    public async Task InvokeAsync(HttpContext context)
    {
        if (context.Response.StatusCode == StatusCodes.Status404NotFound)
        {
            context.Request.Path = "/client/errors/404";
        }

        await RequestDelegate(context);
    }
}

Setting a breakpoint with the debugger shows that providing a gibberish URL still is giving a status code of 200 - so my middleware doesn't handle it. How do I capture the a situation where there is no matching route or static file? I am trying to run code only when no route or static file was matched.

24 Replies

nox7•3mo ago

Upon further investigation, it looks like HttpContext has an Endpoint property that is null if no matching route occurred. If I put my middleware at the end of a chain, unless anyone else has any further information - it seems this is how to tell if the request has no matching route and I can use this to assume it will 404.

Unknown User•3mo ago

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nox7•3mo ago

Yeah, I've read through that - unfortunately it doesn't do what I need here. It forces me to use their internal error handling. Or in the case of a custom IExceptionHandler - only when an exception is thrown. I need it to go to custom paths based on specific HttpContext data.

Unknown User•3mo ago

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nox7•3mo ago

UseStatusCodePagesWithReExecute is almost there, but it doesn't give me much controller in directing it to completely different routes Ah, we thought the same thing

Unknown User•3mo ago

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nox7•3mo ago

I guess I could use it and just handle the logic I need within the Controller I redirect to (showing different views). So I'll go down that path

Unknown User•3mo ago

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nox7•3mo ago

MVC/Razor

Unknown User•3mo ago

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nox7•3mo ago

E.g., I am trying to show 3 different 404 views. One for authenticated clients, one for authenticated staff, and one for non-authenticated users

Unknown User•3mo ago

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nox7•3mo ago

There are other situations I need the 404 page to be shown. E.g., when an object is missing from a request Url that has an Id in the parameter. So I wanted to have it all (all 404 scenarios) propagate up to the top and then the top handles it based on the currently authenticated user

nox7•3mo ago

app.UseStatusCodePagesWithReExecute("/errors/{0}");

app.UseStatusCodePagesWithReExecute("/errors/{0}");

nox7•3mo ago

This works well and as I need it to, so thanks.

Unknown User•3mo ago

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nox7•3mo ago

Ah, I see what you mean. That's not a bad idea either.

Unknown User•3mo ago

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nox7•3mo ago

I don't use the normal identity system, but I get what you're saying.

Unknown User•3mo ago

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nox7•3mo ago

I don't use that system in my app

Unknown User•3mo ago

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nox7•3mo ago

Because two users can be logged in at one time I use a custom user system

Unknown User•3mo ago

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Gaming

Programming

ASP Core 8 - Custom 404 Handling