$state.go() in onEnter causes infinite redirect loop

We use the master/detail ui pattern in many of our states, and I commonly want to pre-populate the detail side with the first result from the server. The problem is that doing a state.go() in the onEnter hook results in an infinite loop. Is there a common way to do this?

example plunker: http://plnkr.co/edit/14pumrI7QoDhDD73kJQr?p=preview.

$stateProvider
  .state('posts', {
      url: "/posts",
      templateUrl: "posts-index.html",
      controller: "PostsIndexController",
      resolve: {
        posts: function(Post) {
          return Post.all()
        }
      },
      onEnter: function($state, posts) {
        if (posts.length > 1) {
          $state.go('posts.show', { postId: posts[0].id });
        }
      }
    })
    .state('posts.show', {
      url: "/:postId",
      templateUrl: "posts-show.html",
      controller: "PostsShowController",
      resolve: {
        post: function($stateParams, Post) {
          return Post.find($stateParams.postId)
        }
      }
    })

[christopherthielen]

I think this is a documentation issue.

Any $state.transitionTo (or $state.go) that occurs while another transition is pending effectively cancels the pending transition and replaces it with the new one (TransitionSuperceded). onEnter, onExit, and state controllers are all invoked while the current transition is pending, thus any $state.go from those functions will supercede the pending transition and replace it. The new transition is then attempted and the onEnter/Exit/ctrl is invoked as usual.

Users should be aware of this because it is not intuitively obvious (myself included; I was bit by a similar use case with $state.go in a controller).

@rockwood perhaps you should be checking not if posts.length > 1, but rather if $stateParams.postId is defined?

I’ve created a pull request which detects the infinite loop and terminates the transitionTo request. This doesn’t stop the loop from happening, but hopefully stops the dev from pulling their hair out.

[noblecraft]

@prisonier the call to $timeout returns immediately and allows the onEnter() function to terminate normally without calling $state.go().