ASP.NET MVC歧义操作方法

我有两种冲突的操作方法。基本上，我希望能够使用两条不同的路线（通过项的ID或项的名称及其父项（在不同的父项中，项可以具有相同的名称））进入同一视图。搜索词可用于过滤列表。

例如...

Items/{action}/ParentName/ItemName
Items/{action}/1234-4321-1234-4321

这是我的动作方法（也有Remove动作方法）...

// Method #1
public ActionResult Assign(string parentName, string itemName) { 
    // Logic to retrieve item's ID here...
    string itemId = ...;
    return RedirectToAction("Assign", "Items", new { itemId });
}

// Method #2
public ActionResult Assign(string itemId, string searchTerm, int? page) { ... }

这是路线...

routes.MapRoute("AssignRemove",
                "Items/{action}/{itemId}",
                new { controller = "Items" }
                );

routes.MapRoute("AssignRemovePretty",
                "Items/{action}/{parentName}/{itemName}",
                new { controller = "Items" }
                );

我理解为什么会发生错误，因为page参数可以为null，但是我无法找出解决该错误的最佳方法。一开始我的设计不好吗？我曾考虑过将Method #1的签名扩展为包括搜索参数，然后将逻辑Method #2移到它们都将调用的私有方法中，但是我认为这不会真正解决歧义。

任何帮助将不胜感激。

实际解决方案（基于李维斯的答案）

我添加了以下课程...

public class RequireRouteValuesAttribute : ActionMethodSelectorAttribute {
    public RequireRouteValuesAttribute(string[] valueNames) {
        ValueNames = valueNames;
    }

    public override bool IsValidForRequest(ControllerContext controllerContext, MethodInfo methodInfo) {
        bool contains = false;
        foreach (var value in ValueNames) {
            contains = controllerContext.RequestContext.RouteData.Values.ContainsKey(value);
            if (!contains) break;
        }
        return contains;
    }

    public string[] ValueNames { get; private set; }
}

然后修饰动作方法...

[RequireRouteValues(new[] { "parentName", "itemName" })]
public ActionResult Assign(string parentName, string itemName) { ... }

[RequireRouteValues(new[] { "itemId" })]
public ActionResult Assign(string itemId) { ... }

MVC不支持仅基于签名的方法重载，因此将失败：

public ActionResult MyMethod(int someInt) { /* ... */ }
public ActionResult MyMethod(string someString) { /* ... */ }

但是，它确实支持基于属性的方法重载：

[RequireRequestValue("someInt")]
public ActionResult MyMethod(int someInt) { /* ... */ }

[RequireRequestValue("someString")]
public ActionResult MyMethod(string someString) { /* ... */ }

public class RequireRequestValueAttribute : ActionMethodSelectorAttribute {
    public RequireRequestValueAttribute(string valueName) {
        ValueName = valueName;
    }
    public override bool IsValidForRequest(ControllerContext controllerContext, MethodInfo methodInfo) {
        return (controllerContext.HttpContext.Request[ValueName] != null);
    }
    public string ValueName { get; private set; }
}

在上面的示例中，该属性只说“如果请求中存在键xxx，则此方法匹配”。如果更适合您的目的，您还可以按路由（controllerContext.RequestContext）中包含的信息进行筛选。

路线中的参数{roleId}，{applicationName}并且{roleName}与操作方法中的参数名称不匹配。我不知道这是否重要，但是要弄清楚您的意图是很难的。

您的itemId是否符合可以通过正则表达式匹配的模式？如果是这样，则可以在路由中添加约束，以便仅将与模式匹配的url标识为包含itemId。

如果您的itemId仅包含数字，则可以使用：

routes.MapRoute("AssignRemove",
                "Items/{action}/{itemId}",
                new { controller = "Items" },
                new { itemId = "\d+" }
                );

编辑：您还可以向AssignRemovePretty路径添加约束，以便{parentName}和{itemName}都是必需的。

编辑2：另外，由于您的第一个动作只是重定向到第二个动作，因此可以通过重命名第一个动作来消除一些歧义。

// Method #1
public ActionResult AssignRemovePretty(string parentName, string itemName) { 
    // Logic to retrieve item's ID here...
    string itemId = ...;
    return RedirectToAction("Assign", itemId);
}

// Method #2
public ActionResult Assign(string itemId, string searchTerm, int? page) { ... }

然后在路由中指定动作名称，以强制调用正确的方法：

routes.MapRoute("AssignRemove",
                "Items/Assign/{itemId}",
                new { controller = "Items", action = "Assign" },
                new { itemId = "\d+" }
                );

routes.MapRoute("AssignRemovePretty",
                "Items/Assign/{parentName}/{itemName}",
                new { controller = "Items", action = "AssignRemovePretty" },
                new { parentName = "\w+", itemName = "\w+" }
                );

另一种方法是重命名其中一种方法，因此不会发生冲突。例如

// GET: /Movies/Delete/5
public ActionResult Delete(int id = 0)

// POST: /Movies/Delete/5
[HttpPost, ActionName("Delete")]
public ActionResult DeleteConfirmed(int id = 0)

参见http://www.asp.net/mvc/tutorials/getting-started-with-mvc3-part9-cs

最近，我借此机会改进了@Levi的答案，以支持我必须处理的更广泛的场景，例如：多参数支持，匹配其中任何一个（而不是全部），甚至都不匹配。

这是我现在使用的属性：

/// <summary>
/// Flags an Action Method valid for any incoming request only if all, any or none of the given HTTP parameter(s) are set,
/// enabling the use of multiple Action Methods with the same name (and different signatures) within the same MVC Controller.
/// </summary>
public class RequireParameterAttribute : ActionMethodSelectorAttribute
{
    public RequireParameterAttribute(string parameterName) : this(new[] { parameterName })
    {
    }

    public RequireParameterAttribute(params string[] parameterNames)
    {
        IncludeGET = true;
        IncludePOST = true;
        IncludeCookies = false;
        Mode = MatchMode.All;
    }

    public override bool IsValidForRequest(ControllerContext controllerContext, MethodInfo methodInfo)
    {
        switch (Mode)
        {
            case MatchMode.All:
            default:
                return (
                    (IncludeGET && ParameterNames.All(p => controllerContext.HttpContext.Request.QueryString.AllKeys.Contains(p)))
                    || (IncludePOST && ParameterNames.All(p => controllerContext.HttpContext.Request.Form.AllKeys.Contains(p)))
                    || (IncludeCookies && ParameterNames.All(p => controllerContext.HttpContext.Request.Cookies.AllKeys.Contains(p)))
                    );
            case MatchMode.Any:
                return (
                    (IncludeGET && ParameterNames.Any(p => controllerContext.HttpContext.Request.QueryString.AllKeys.Contains(p)))
                    || (IncludePOST && ParameterNames.Any(p => controllerContext.HttpContext.Request.Form.AllKeys.Contains(p)))
                    || (IncludeCookies && ParameterNames.Any(p => controllerContext.HttpContext.Request.Cookies.AllKeys.Contains(p)))
                    );
            case MatchMode.None:
                return (
                    (!IncludeGET || !ParameterNames.Any(p => controllerContext.HttpContext.Request.QueryString.AllKeys.Contains(p)))
                    && (!IncludePOST || !ParameterNames.Any(p => controllerContext.HttpContext.Request.Form.AllKeys.Contains(p)))
                    && (!IncludeCookies || !ParameterNames.Any(p => controllerContext.HttpContext.Request.Cookies.AllKeys.Contains(p)))
                    );
        }
    }

    public string[] ParameterNames { get; private set; }

    /// <summary>
    /// Set it to TRUE to include GET (QueryStirng) parameters, FALSE to exclude them:
    /// default is TRUE.
    /// </summary>
    public bool IncludeGET { get; set; }

    /// <summary>
    /// Set it to TRUE to include POST (Form) parameters, FALSE to exclude them:
    /// default is TRUE.
    /// </summary>
    public bool IncludePOST { get; set; }

    /// <summary>
    /// Set it to TRUE to include parameters from Cookies, FALSE to exclude them:
    /// default is FALSE.
    /// </summary>
    public bool IncludeCookies { get; set; }

    /// <summary>
    /// Use MatchMode.All to invalidate the method unless all the given parameters are set (default).
    /// Use MatchMode.Any to invalidate the method unless any of the given parameters is set.
    /// Use MatchMode.None to invalidate the method unless none of the given parameters is set.
    /// </summary>
    public MatchMode Mode { get; set; }

    public enum MatchMode : int
    {
        All,
        Any,
        None
    }
}

有关更多信息和操作方法示例，请查看我撰写的有关此主题的博客文章。

routes.MapRoute("AssignRemove",
                "Items/{parentName}/{itemName}",
                new { controller = "Items", action = "Assign" }
                );

考虑使用MVC Contribs测试路由库来测试您的路由

"Items/parentName/itemName".Route().ShouldMapTo<Items>(x => x.Assign("parentName", itemName));