在ASP.NET MVC中发布后如何更改表单值？

Question

我想在将表单值传递给控制器​​的操作之前对其进行更改。 但是它抛出Collection is read-only.

public class PersonController : Controller
{
    public ActionResult Add()
    {
        return View();
    }

    [HttpPost]
    [PersianDateConvertor("birthday")]
    public ActionResult Add(FormCollection collection)
    {
        string firstName = collection["firstName"];
        string lastName = collection["lastName"];
        string birthday = collection["birthday"];

        return View();
    }
}
public class PersianDateConvertorAttribute : ActionFilterAttribute
{
    string[] fields;
    public PersianDateConvertorAttribute(params string[] persianDateFieldNames)
    {
        if (persianDateFieldNames == null)
            fields = new string[] { };
        else
            fields = persianDateFieldNames;
    }

    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        foreach (var field in fields)
        {
            string value = filterContext.HttpContext.Request.Form[field];
            filterContext.HttpContext.Request.Form.Remove(field); //throws Collection is read-only
            filterContext.HttpContext.Request.Form.Add(field, ConvertToGregorian(value));
            // or filterContext.HttpContext.Request.Form[field] = ConvertToGregorian(value);
        }

        base.OnActionExecuting(filterContext);
    }
}

Answer 1

如果我理解正确，则想在绑定过程中修改DateTime的行为。 代替使用属性，我将使用ModelBinder更改日期字符串的格式。

在转换来自多种区域性的十进制值时，我做了类似的事情：（代码取自博客文章，它不是我的，但我不记得源代码了。抱歉）

using System;
using System.Globalization;
using System.Web.Mvc;

public class DecimalModelBinder : IModelBinder
{
  public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
  {
    ValueProviderResult valueResult = bindingContext.ValueProvider.GetValue(bindingContext.ModelName);
    ModelState modelState = new ModelState { Value = valueResult };
    object actualValue = null;
    try
    {
      actualValue = Convert.ToDecimal(valueResult.AttemptedValue, CultureInfo.CurrentCulture);
    }
    catch (FormatException e)
    {
      modelState.Errors.Add(e);
    }
    bindingContext.ModelState.Add(bindingContext.ModelName, modelState);
    return actualValue;
  }
}

在global.asax中，您注册活页夹

protected void Application_Start()
{
  AreaRegistration.RegisterAllAreas();
  RegisterGlobalFilters(GlobalFilters.Filters);
  RegisterRoutes(RouteTable.Routes);

  ModelBinders.Binders.Add(typeof(decimal), new DecimalModelBinder());

}

即时通讯，这是一种更好的方法，您不必为每个操作都添加属性