通过ASP.NET MVC Action Filter修改表单值

Question

我正在尝试通过MVC操作过滤器修改添加到购物车的产品数量。这就是我所拥有的，但它不起作用：

public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        var settings = _settingService.LoadSetting<RRGamesBaseSettings>();
        var customer = _workContext.CurrentCustomer;         

        if (customer.IsInCustomerRole(settings.ResellerRoleSystemName))
        {
            var productId = Convert.ToInt32(filterContext.ActionParameters["productId"]);
            var formCollection = new FormCollection(filterContext.Controller.ControllerContext.HttpContext.Request.Fo‌​rm);
            var productService = EngineContext.Current.Resolve<IRRGamesProductService>();
            var product = productService.GetProductById(productId);
            int quantity = 0;
            string fieldName = string.Format("addtocart_{0}.EnteredQuantity", productId);

            int.TryParse(formCollection[fieldName], out quantity);

            if (product != null)
            {
                if (quantity < product.CaseQuantity)
                {
                    quantity = product.CaseQuantity;
                    formCollection[fieldName] = quantity.ToString();
                }
            }                
        }

        base.OnActionExecuting(filterContext);
    }

当我将formCollection [formKey]设置为新数量时，它不会在转到控制器操作时更新表单值。

Answer 1

我想通了，很简单

formCollection.Set(fieldName, quantity.ToString());

filterContext.ActionParameters["form"] = formCollection;