为什么存在路由可以视为没有路由匹配（RoutingError）？

Question

The rails server says

Started POST "/user/1/follow" 

ActionController::RoutingError (No route matches [POST] "/user/1/follow"):

But using rake routes

         Prefix Verb   URI Pattern                     Controller#Action
 followers_user GET    /users/:id/followers(.:format)  users#followers
followings_user GET    /users/:id/followings(.:format) users#followings
    follow_user POST   /users/:id/follow(.:format)     users#follow

Based on the information above I have no idea why the route exist can be regarded as no route matches(RoutingError). It seems that the route does exist.

Below is other information maybe relevant to this issue. I'm using jquery to trigger the route by

  $.ajax({
            url: '/user/'+userId+'/follow',
            type: 'POST',

        });

And users#follow is defined as

    def follow
            if current_user?(@user)
                    flash[:error] = "You cannot follow yourself"
            elsif current_user.following?(@user)
                    flash[:error] = "You already follow #{@user.name}"
            end
            if request.xhr?
                    render status: current_user.follow(@user) ? 200 : 400, nothing: true
            end
    end

Answer 1

You've defined your route as

follow_user POST   /users/:id/follow(.:format)     users#follow

But in the jQuery snippet, you're using /user/... instead of /users/...

Answer 2

The path of your route is different in the jquery post, the correct route 'users/1/follow' , a super tip I use in my work, use the gem js-routes that provides the path of their routes to be accessed in JavaScripts.

Hope this helps :)