[added] Router.AsyncState mixin

Helps with #57

Author: mjackson

modules/helpers/resolveAsyncState.js

@@ -0,0 +1,24 @@
+var Promise = require('es6-promise').Promise;
+
+/**
+ * Resolves all values in the given stateDescription object
+ * and calls the setState function with new state as they resolve.
+ */
+function resolveAsyncState(stateDescription, setState) {
+  if (stateDescription == null)
+    return Promise.resolve({});
+
+  var keys = Object.keys(stateDescription);
+  
+  return Promise.all(
+    keys.map(function (key) {
+      return Promise.resolve(stateDescription[key]).then(function (value) {
+        var newState = {};
+        newState[key] = value;
+        setState(newState);
+      });
+    })
+  );
+}
+
+module.exports = resolveAsyncState;

modules/main.js

@@ -7,6 +7,7 @@ exports.replaceWith = require('./helpers/replaceWith');
 exports.transitionTo = require('./helpers/transitionTo');
 
 exports.ActiveState = require('./mixins/ActiveState');
+exports.AsyncState = require('./mixins/AsyncState');
 
 // Backwards compat with 0.1. We should
 // remove this when we ship 1.0.

modules/mixins/AsyncState.js

@@ -0,0 +1,106 @@
+var React = require('react');
+var resolveAsyncState = require('../helpers/resolveAsyncState');
+
+/**
+ * A mixin for route handler component classes that fetch at least
+ * part of their state asynchronously. Classes that use it should
+ * declare a static `getInitialAsyncState` method that fetches state
+ * for a component after it mounts. This function is given three
+ * arguments: 1) the current route params, 2) the current query and
+ * 3) a function that can be used to set state as it is received.
+ *
+ * Example:
+ *
+ *   var User = React.createClass({
+ *   
+ *     statics: {
+ *   
+ *       getInitialAsyncState: function (params, query, setState) {
+ *         // If you don't need to do anything async, just update
+ *         // the state immediately and you're done.
+ *         setState({
+ *           user: UserStore.getUserByID(params.userID)
+ *         });
+ *   
+ *         // Or, ignore the setState argument entirely and return a
+ *         // hash with keys named after the state variables you want
+ *         // to set. The values may be immediate values or promises.
+ *         return {
+ *           user: getUserByID(params.userID) // may be a promise
+ *         };
+ *   
+ *         // Or, stream your data!
+ *         var buffer = '';
+ *   
+ *         return {
+ *
+ *           // Same as above, the stream state variable is set to the
+ *           // value returned by this promise when it resolves.
+ *           stream: getStreamingData(params.userID, function (chunk) {
+ *             buffer += chunk;
+ *   
+ *             // Notify of progress.
+ *             setState({
+ *               streamBuffer: buffer
+ *             });
+ *           })
+ *   
+ *         };
+ *       }
+ *   
+ *     },
+ *   
+ *     getInitialState: function () {
+ *       return {
+ *         user: null,        // Receives a value when getUserByID resolves.
+ *         stream: null,      // Receives a value when getStreamingData resolves.
+ *         streamBuffer: ''   // Used to track data as it loads.
+ *       };
+ *     },
+ *   
+ *     render: function () {
+ *       if (!this.state.user)
+ *         return <LoadingUser/>;
+ *   
+ *       return (
+ *         <div>
+ *           <p>Welcome {this.state.user.name}!</p>
+ *           <p>So far, you've received {this.state.streamBuffer.length} data!</p>
+ *         </div>
+ *       );
+ *     }
+ *   
+ *   });
+ *
+ * When testing, use the `initialAsyncState` prop to simulate asynchronous
+ * data fetching. When this prop is present, no attempt is made to retrieve
+ * additional state via `getInitialAsyncState`.
+ */
+var AsyncState = {
+
+  propTypes: {
+    initialAsyncState: React.PropTypes.object
+  },
+
+  getInitialState: function () {
+    return this.props.initialAsyncState || null;
+  },
+
+  updateAsyncState: function (state) {
+    if (this.isMounted())
+      this.setState(state);
+  },
+
+  componentDidMount: function () {
+    if (this.props.initialAsyncState || !this.constructor.getInitialAsyncState)
+      return;
+
+    resolveAsyncState(
+      this.constructor.getInitialAsyncState(this.props.params, this.props.query, this.updateAsyncState),
+      this.updateAsyncState
+    );
+  }
+
+};
+
+module.exports = AsyncState;

specs/AsyncState.spec.js

@@ -0,0 +1,47 @@
+require('./helper');
+var Promise = require('es6-promise').Promise;
+var AsyncState = require('../modules/mixins/AsyncState');
+
+describe('AsyncState', function () {
+
+
+  describe('a component that fetches part of its state asynchronously', function () {
+    it('resolves all state variables correctly', function (done) {
+      var User = React.createClass({
+        mixins: [ AsyncState ],
+        statics: {
+          getInitialAsyncState: function (params, query, setState) {
+            setState({
+              immediateValue: 'immediate'
+            });
+
+            setTimeout(function () {
+              setState({
+                delayedValue: 'delayed'
+              });
+            });
+
+            return {
+              promisedValue: Promise.resolve('promised')
+            };
+          }
+        },
+        render: function () {
+          return null;
+        }
+      });
+
+      var user = TestUtils.renderIntoDocument(
+        User()
+      );
+
+      setTimeout(function () {
+        expect(user.state.immediateValue).toEqual('immediate');
+        expect(user.state.delayedValue).toEqual('delayed');
+        expect(user.state.promisedValue).toEqual('promised');
+        done();
+      }, 20);
+    });
+  });
+
+});

specs/main.js

@@ -1,6 +1,7 @@
 // TODO: this is for webkpack-karma to only create one build instead of a build
 // for every spec file, there must be some sort of config but I can't find it ...
 require('./ActiveStore.spec.js');
+require('./AsyncState.spec.js');
 require('./Path.spec.js');
 require('./Route.spec.js');
 require('./RouteStore.spec.js');