ASP.NET MVC 5属性路由：使用多个参数时，Url.Action返回null

Question

This kind of question has been asked before on SO ( post 1 , post 2 , post 3 ), but none of them was able to help me.

I have the following route (defined inside a LandingController class):

[HttpGet]
[Route("connections/{city:name}/map{page?}", Order = 2)]
public Task<ActionResult> Connections(string city, int page = 1)

for which I am trying to generate an URL in my Razor template like this:

@Url.Action("Connections", "Landing", new { city = "madrid", page = 1 })

or

@Url.Action("Connections", new { city = "madrid", page = 1 })

Both these calls return null . Anyone has an idea why?

However if I omit the page parameter in the route template (doing [Route("connections/{city:name}/map", Order = 2)] ), the following URL is generated: /connections/madrid/map/?page=1 , which is not what I want, but it shows that I am doing something wrong with my calls above.

Answer 1

[HttpGet]
[Route("connections/{city:name}/map{page?}", Order = 2)]
public Task<ActionResult> Connections(string city, int page = 1)

Pretty sure your routing is incorrect, {city:name} what is name? I don't recall any having a constraint type name.

Your attribute routing should be as simple as this:

[Route("connections/{city}/map/{page?}", Order = 2)]

If you want to add constraint to page as integer it would be:

[Route("connections/{city}/map/{page:int?}", Order = 2)]