Middleware to set response ContentType

Question

In our ASP.NET Core based web application, we want the following: certain requested file types should get custom ContentType\'s in response. E.g. .map should map to

Answer 1

Try to use HttpContext.Response.OnStarting callback. This is the last event that is fired before the headers are sent.

public async Task Invoke(HttpContext context)
{
    context.Response.OnStarting((state) =>
    {
        if (context.Response.StatusCode == (int)HttpStatusCode.OK)
        {
           if (context.Request.Path.Value.EndsWith(".map"))
           {
             context.Response.ContentType = "application/json";
           }
        }          
        return Task.FromResult(0);
    }, null);

    await nextMiddleware.Invoke(context);
}

Answer 2

Using an overload of OnStarting method:

public async Task Invoke(HttpContext context)
{
    context.Response.OnStarting(() =>
    {
        if (context.Response.StatusCode == (int) HttpStatusCode.OK &&
            context.Request.Path.Value.EndsWith(".map"))
        {
            context.Response.ContentType = "application/json";
        }

        return Task.CompletedTask;
    });

    await nextMiddleware.Invoke(context);
}