ASP.NET MVC2站点是否可以使用可选的枚举路由参数？如果是这样，如果没有提供，我们可以默认该值吗？

can I have a route like...

我可以有像...这样的路线吗？

routes.MapRoute(
    "Boundaries-Show",
    "Boundaries",
     new 
     {
         controller = "Boundaries", 
         action = "Show",
         locationType = UrlParameter.Optional
     });

Where the action method is...

行动方法是......

[HttpGet]
public ActionResult Show(int? aaa, int? bbb, LocationType locationType) { ... }

and if the person doesn't provide a value for locationType .. then it defaults to LocationType.Unknown.

如果此人没有为locationType提供值，则默认为LocationType.Unknown。

Is this possible?

这可能吗？

Update #1

I've stripped back the action method to contain ONE method (just until I get this working). It now looks like this ..

我已经剥离了动作方法以包含一个方法（直到我得到这个工作）。它现在看起来像..

[HttpGet]
public ActionResult Show(LocationType locationType = LocationType.Unknown) { .. }

.. and I get this error message...

..我收到此错误消息...

The parameters dictionary contains an invalid entry for parameter 'locationType' for method 'System.Web.Mvc.ActionResult Show(MyProject.Core.LocationType)' in 'MyProject.Controllers.GeoSpatialController'. The dictionary contains a value of type 'System.Int32', but the parameter requires a value of type 'MyProject.Core.LocationType'. Parameter name: parameters

参数字典包含参数'locationType'的无效条目，用于'MyProject.Controllers.GeoSpatialController'中方法'System.Web.Mvc.ActionResult Show（MyProject.Core.LocationType）'。字典包含“System.Int32”类型的值，但该参数需要“MyProject.Core.LocationType”类型的值。参数名称：参数

Is it thinking that the optional route parameter LocationType is an int32 and not a custom Enum ?

是否认为可选路由参数LocationType是int32而不是自定义Enum？

2 个解决方案

#1

You can supply a default value like so:

您可以提供如下默认值：

public ActionResult Show(int? aaa, int? bbb, LocationType locationType = LocationType.Unknown) { ... }

UPDATE:

更新：

Or if you are using .NET 3.5:

或者如果您使用的是.NET 3.5：

public ActionResult Show(int? aaa, int? bbb, [DefaultValue(LocationType.Unknown)] LocationType locationType) { ... }

UPDATE 2:

更新2：

public ActionResult Show(int? aaa, int? bbb, int locationType = 0) {
  var _locationType = (LocationType)locationType;
}

public enum LocationType {
    Unknown = 0,
    Something = 1
}

#2

You can add the DefaultValue attribute to your action method:

您可以将DefaultValue属性添加到您的操作方法：

[HttpGet]
public ActionResult Show(int? aaa, int? bbb, [DefaultValue(LocationType.Unknown)]LocationType locationType) { ... }

or use optional parameters depending on what language version your using:

或使用可选参数，具体取决于您使用的语言版本：

[HttpGet]
public ActionResult Show(int? aaa, int? bbb, LocationType locationType = LocationType.Default) { ... }

#1