在actionfilterattribute中重复常见错误信息逻辑

public override void OnActionExecuting(ActionExecutingContext filterContext)
{
    // Notice that the controller action hasn't been called yet, so
    // don't expect ModelState.IsValid=false here if you have 
    // ModelState.AddModelError inside your controller action
    // (you shouldn't be doing validation in your controller action anyway)
    bool result = filterContext.Controller.ViewData.ModelState.IsValid;
    if (!result)
    {
        // the model that resulted from model binding is not valid 
        // => prepare a ViewResult using the model to return
        var result = new ViewResult();
        result.ViewData.Model = new GenericResultModel() { HasError = true };
        filterContext.Result = result;
    }
    else
    {
        // call the action method only if the model is valid after binding
        base.OnActionExecuting(filterContext);
    }
}