ASP.Net MVC HttpRequestValidationException - Catch Error and Capture Input?

I've seen several posts about turning off HttpRequestValidation for controllers/actions to get around this error, but I really want it to be enabled for the most part. There are few enough instances where I want to bypass the validation that I am willing to wrap a try/catch block around it:

string searchTerm = string.Empty;
try {
    searchTerm = Request.QueryString["q"];
} catch (HttpRequestValidationException ex) {
    // What can I do here to captu开发者_高级运维re the value? Is parsing the error message the only way?
    // Seems like ex.Data property would be a good place for Microsoft to stick values if
    // people wanted to do something with them, but ex.Data is empty.
}

Again, this is only for certain fields within forms, so I DO NOT want to disable validation for an entire controller or action. I want the added protection there for fields I have not specifically handled.

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Did you check out the AllowHTML attribute? It might be exactly what you need.

public class MyModel
{
    public string ValidatedField {get; set;} // no HTML allowed here!

    [AllowHtml]
    public string NonValidatedField {get; set;} // user can enter HTML
}