Angular UI Router - Default Parameter

Question

Is there anyway to specify a default parameter for every route using the Angular UI Router?

My app is entered through the context of another application by selecting a user and then navigating to my application. The URL in my application will always have the user ID in the URL so that people can bookmark the URL, email it, etc. So, as you navigate around, the URL always follows a scheme of:

#/{userId}/view/...
#/{userId}/edit/...

etc.

This userId will always be the same for a user inside the app for any route they go to. If they happen to log out, go back to the main app, select a new user and come back to my app, this userId will change, but will be the same value for every route.

Is there anyway to read this value from say a service/factory and then plug it into every route?

EDIT:

I should mention I want to avoid having to explicitly set this parameter on every route when I navigate to a state. For example, I don't want to have to do ui-sref="new-state({userId : blah})" every time I navigate to a new state. That userId will never change in the context of my application.

EDIT AGAIN:

I actually went about this a different way concerning the requirement to not have to send 'userId' to every route manually. Instead of using a directive, I used a $provide.decorator to add this functionality to the 'go' method. I've added an answer below to what I did.

Answer 1

You can declare an abstract parent state from which child states inherit:

$stateProvider
  .state('user', {
     url: '/:userid',
     abstract: true,
     resolve: 
       // assuming some kind of User resource factory
       currentUser: function($stateParams, User) {
         return User.get($stateParams.userid);
       }
     }
   })
  .state('user.view', {
     url: '/view', // actual url /:userid/view
     controller: function($scope, currentUser) {
       // currentUser resource available
     }
   });
  .state('user.edit', {
     url: '/edit', // actual url /:userid/edit
     controller: function($scope, currentUser) {
       // currentUser resource available
     }
   });

In terms of navigating to a state, you need to pass in the desired user:

$state.go('user.view', {userid: 'myuserid'});

As a consequence it might make sense to create some kind of .go() wrapper method on your currentUser service, so that you needn't specify the user id each time.

UPDATE:

To counter the problem posted in your edit, you could introduce a directive like this:

angular.module('app')
  .directive('userSref', function($state) {               
     return function(scope, elem, attrs) {
       var state = 'user.' + attrs.userSref;

       elem.bind('click', function() {
         $state.go(state, {userid: $state.params.userid});
       });           

       scope.$on('$destroy', function() {
         elem.unbind('click');
       });
     };
  });

Then, any future links to user-based states can be done so with:

<a user-sref="view">View User</a>