Implementing $state.go(), for relative transitions & param inheritance.

Author: nateabele

src/common.js

@@ -35,6 +35,49 @@ function merge(dst) {
   return dst;
 }
 
+/**
+ * Finds the common ancestor path between two states.
+ *
+ * @param {Object} first The first state.
+ * @param {Object} second The second state.
+ * @return {Array} Returns an array of state names in descending order, not including the root.
+ */
+function ancestors(first, second) {
+  var path = [];
+
+  for (var n in first.path) {
+    if (first.path[n] === "") continue;
+    if (!second.path[n]) break;
+    path.push(first.path[n]);
+  }
+  return path;
+}
+
+/**
+ * Merges a set of parameters with all parameters inherited between the common parents of the
+ * current state and a given destination state.
+ *
+ * @param {Object} currentParams The value of the current state parameters ($stateParams).
+ * @param {Object} newParams The set of parameters which will be composited with inherited params.
+ * @param {Object} $current Internal definition of object representing the current state.
+ * @param {Object} $to Internal definition of object representing state to transition to.
+ */
+function inheritParams(currentParams, newParams, $current, $to) {
+  var parents = ancestors($current, $to), parentParams, inherited = {}, inheritList = [];
+
+  for (var i in parents) {
+    if (!parents[i].params || !parents[i].params.length) continue;
+    parentParams = parents[i].params;
+
+    for (var j in parentParams) {
+      if (inheritList.indexOf(parentParams[j]) >= 0) continue;
+      inheritList.push(parentParams[j]);
+      inherited[parentParams[j]] = currentParams[parentParams[j]];
+    }
+  }
+  return extend({}, inherited, newParams);
+}
+
 angular.module('ui.util', ['ng']);
 angular.module('ui.router', ['ui.util']);
 angular.module('ui.state', ['ui.router', 'ui.util']);

src/state.js

@@ -199,8 +199,11 @@ function $StateProvider(   $urlRouterProvider,   $urlMatcherFactory,           $
       transition: null
     };
 
-    // $state.go = function go(to, params) {
-    // };
+    $state.go = function go(to, params, options) {
+      var toState = findState(to, $state.$current);
+      params = inheritParams($stateParams, params || {}, $state.$current, toState);
+      return this.transitionTo(toState, params, options);
+    };
 
     $state.transitionTo = function transitionTo(to, toParams, updateLocation) {
       if (!isDefined(updateLocation)) updateLocation = true;

test/stateSpec.js

@@ -210,6 +210,30 @@ describe('state', function () {
     }));
   });
 
+  describe('.go()', function() {
+    it('transitions to a relative state', inject(function ($state, $q) {
+      $state.transitionTo('about.person.item', { id: 5 });
+      $q.flush();
+      $state.go('^.^.sidebar');
+      $q.flush();
+      expect($state.$current.name).toBe('about.sidebar');
+    }));
+
+    it('keeps parameters from common ancestor states', inject(function ($state, $stateParams, $q) {
+      $state.transitionTo('about.person', { person: 'bob' });
+      $q.flush();
+
+      $state.go('^item', { id: 5 });
+      $q.flush();
+
+      expect($state.$current.name).toBe('about.person.item');
+      expect($stateParams).toEqual({ person: 'bob', id: '5' });
+
+      $state.go('^.^.sidebar');
+      $q.flush();
+      expect($state.$current.name).toBe('about.sidebar');
+    }));
+  });
 
   describe('.current', function () {
     it('is always defined', inject(function ($state) {
@@ -345,7 +369,7 @@ describe('state', function () {
     }));
   });
 
-  describe('default properties', function () {
+  describe('default properties', function() {
     it('should always have a name', inject(function ($state, $q) {
       $state.transitionTo(A);
       $q.flush();
@@ -403,5 +427,11 @@ describe('state', function () {
     it('should always have a resolve object', inject(function ($state) {
       expect($state.$current.resolve).toEqual({});
     }));
+
+    it('should include itself and parent states', inject(function ($state, $q) {
+      $state.transitionTo(DD);
+      $q.flush();
+      expect($state.$current.includes).toEqual({ '': true, D: true, DD: true });
+    }));
   });
 });