c# - ASP.NET MVC 5 路由可选参数

Question

我的 ApiController 中有一个 Action，我想从特定链接调用它，所以我创建了这个简单的路由

[Route("Rest/GetName/{name}")]
public IHttpActionResult GetName(string name) {
    // cut - code here is trivial but long, I just fill in an object to return as Json code
    return Json(myObject);
}

它工作正常，但我想将参数设为可选。根据documentation在路由中的参数名末尾加一个问号点应该就可以了

[Route("Rest/GetName/{name?}")]

如果我不提供可选参数，这样我会得到一个错误，所以

.../Rest/GetName/AnyName --> ok
.../Rest/GetName/ --> error (see below)

{"Message":"No HTTP resource was found that matches the request URI 'https://localhost/miApp/Rest/GetName'.","MessageDetail":"No action was found on the controller 'Rest' that matches the request."}

Answer 1

Web API 需要显式设置可选值，即使对于可为 null 的类型和类也是如此。

对可选参数使用默认值:

[Route("Rest/GetName/{name?}")]
public IHttpActionResult GetName(string name = null) {
    // cut - code here is trivial but long, I just fill in an object to return as Json code
    return Json(myObject);
}

不要忘记路由注册:

httpConfig.MapHttpAttributeRoutes()