C# WebAPI 路由模板中的通配符
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Wildcard in WebAPI Route template
提问by ValidfroM
I have set up a route template:
我已经设置了一个路由模板：
config.Routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{controller}/{id}/{*wildcard}",
defaults: new { id = RouteParameter.Optional }
);
controller's action signature:
控制器的动作签名：
public IEnumerable<object> Get(Int64 id,string abc)
I tried to match it with URL http://mymachine.com/api/Individuals/1?abc=4, but it gives me an exception
我试图将它与 URL http://mymachine.com/api/Individuals/1?abc=4匹配，但它给了我一个例外
{"$id":"1","Message":"An error has occurred.","ExceptionMessage":"Object reference not set to an instance of an object.","ExceptionType":"System.NullReferenceException","StackTrace":" at System.Web.Http.ValueProviders.Providers.RouteDataValueProvider.d__4.MoveNext()\r\n
{"$id":"1","Message":"发生错误。","ExceptionMessage":"未将对象引用设置为对象的实例。","ExceptionType":"System.NullReferenceException", "StackTrace":" 在 System.Web.Http.ValueProviders.Providers.RouteDataValueProvider.d__4.MoveNext()\r\n
Strangely, http://mymachine.com/api/Individuals?id=1&abc=4does match with the controller,action and parameters.
奇怪的是，http://mymachine.com/api/Individuals?id=1& abc=4确实与控制器、动作和参数匹配。
I thought "{id}" of "api/{controller}/{id}/{*wildcard}" will work.
我想： “ （编号）的” “API / {控制器} / {ID}/ {*}通配符”将起作用。
Why?
为什么？
采纳答案by gooid
The wildcard will tell the routing engine to match the rest of the URI to a route parameter (for an example, see "Get Books By Publication Date" section in this article).
通配符将告诉路由引擎到URI的其他部分相匹配的路由参数（例如，请参阅“获取书籍出版日期”一节本文中）。
It does not mean match any arbitrary named variable to any parameter - this is something WebApi does by default with items on the querystring regardless of your route configuration (hence why you second URI worked - it didn't match any route).
这并不意味着将任何任意命名变量与任何参数匹配 - 这是 WebApi 默认情况下对查询字符串上的项目所做的事情，而不管您的路由配置（因此您的第二个 URI 工作 - 它不匹配任何路由）。
It did not match {id}in your route because it was expecting a parameter called {wildcard}that was not marked as optional.
它{id}在您的路由中不匹配，因为它期望调用{wildcard}一个未标记为可选的参数。
To illustrate, if you simply changed 'wildcard' to 'abc':
为了说明，如果您只是将 'wildcard' 更改为 'abc'：
config.Routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{controller}/{id}/{*abc}",
defaults: new {id = RouteParameter.Optional});
Then it would successfully match the following URI:
然后它将成功匹配以下 URI：
http://mymachine.com/api/Individual/1/a/b/c
http://mymachine.com/api/Individual/1/a/b/c
With the values id=1, abc=a/b/c
随着价值观 id=1, abc=a/b/c
To fix, simply remove the wildcard from your route, so that it looks like this:
要修复，只需从您的路线中删除通配符，使其看起来像这样：
config.Routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{controller}/{id}",
defaults: new {id = RouteParameter.Optional});
回答by Nam Hoang
The answer from gooid is correct. I just want to answer the 2nd part of the question:
gooid的回答是正确的。我只想回答问题的第二部分：
Strangely, http://mymachine.com/api/Individuals?id=1&abc=4does match with the controller,action and parameters.
奇怪的是，http://mymachine.com/api/Individuals?id=1& abc=4确实与控制器、动作和参数匹配。
Since you have id = RouteParameter.Optional, if the route doesn't provide id, it still matchesthe route template. The placeholder {*wildcard} looks for the rest of the route and put it into the Route Dictionary under the key "wildcard". In this case, it is empty string (or null).
因为你有 id = RouteParameter.Optional，如果路由没有提供 id，它仍然匹配路由模板。占位符 {*wildcard} 查找路线的其余部分，并将其放入“通配符”键下的路线词典中。在这种情况下，它是空字符串（或 null）。
Remember that the query parameters also go into the Route Dictionary. Therefore, your Route Dictionary will be: { "id": "1", "abc": "4", "wildcard": ""}
请记住，查询参数也会进入路由字典。因此，您的路由字典将是：{ "id": "1", "abc": "4", "wildcard": ""}
For more info, you can look into http://www.asp.net/web-api/overview/web-api-routing-and-actions/routing-in-aspnet-web-api
有关更多信息，您可以查看http://www.asp.net/web-api/overview/web-api-routing-and-actions/routing-in-aspnet-web-api
