[BUGFIX beta] {{get}} helper subscribes to values and can be updated

packages/ember-htmlbars/lib/keywords/get.js

@@ -1,72 +1,125 @@
 import Ember from 'ember-metal/core';
 import isEnabled from 'ember-metal/features';
 import Stream from 'ember-metal/streams/stream';
-import { labelFor } from 'ember-metal/streams/utils';
-import { read, isStream } from 'ember-metal/streams/utils';
+import KeyStream from 'ember-metal/streams/key-stream';
+import { isStream } from 'ember-metal/streams/utils';
 import merge from 'ember-metal/merge';
+import subscribe from 'ember-htmlbars/utils/subscribe';
+import { get } from 'ember-metal/property_get';
+import { set } from 'ember-metal/property_set';
+import {
+  addObserver,
+  removeObserver
+} from 'ember-metal/observer';
+
+function labelFor(source, key) {
+  const sourceLabel = source.label ? source.label : '';
+  const keyLabel = key.label ? key.label : '';
+  return `(get ${sourceLabel} ${keyLabel})`;
+}
 
 if (isEnabled('ember-htmlbars-get-helper')) {
-  var getKeyword = function getKeyword(morph, env, scope, params, hash, template, inverse, visitor) {
-    var objParam = params[0];
-    var pathParam = params[1];
+  const buildStream = function buildStream(params) {
+    const [objRef, pathRef] = params;
 
-    Ember.assert('The first argument to {{get}} must be a stream', isStream(objParam));
+    Ember.assert('The first argument to {{get}} must be a stream', isStream(objRef));
     Ember.assert('{{get}} requires at least two arguments', params.length > 1);
 
-    var getStream = new GetStream(objParam, pathParam);
+    const stream = new DynamicKeyStream(objRef, pathRef);
+
+    return stream;
+  };
 
-    if (morph === null) {
-      return getStream;
+  var getKeyword = function getKeyword(morph, env, scope, params, hash, template, inverse, visitor) {
+    if (!morph) {
+      return buildStream(params);
     } else {
-      env.hooks.inline(morph, env, scope, '-get', [getStream], hash, visitor);
+      let stream;
+      if (morph.linkedResult) {
+        stream = morph.linkedResult;
+      } else {
+        stream = buildStream(params);
+
+        subscribe(morph, env, scope, stream);
+        env.hooks.linkRenderNode(morph, env, scope, null, params, hash);
+
+        morph.linkedResult = stream;
+      }
+      env.hooks.range(morph, env, scope, null, stream, visitor);
     }
 
     return true;
   };
 
-  var GetStream = function GetStream(obj, path) {
-    this.init(`(get ${labelFor(obj)} ${labelFor(path)})`);
-
-    this.objectParam = obj;
-    this.pathParam = path;
-    this.lastPathValue = undefined;
-    this.valueDep = this.addMutableDependency();
+  var DynamicKeyStream = function DynamicKeyStream(source, keySource) {
+    if (!isStream(keySource)) {
+      return new KeyStream(source, keySource);
+    }
+    Ember.assert('DynamicKeyStream error: source must be a stream', isStream(source)); // TODO: This isn't necessary.
 
-    this.addDependency(path);
+    // used to get the original path for debugging and legacy purposes
+    var label = labelFor(source, keySource);
 
-    // This next line is currently only required when the keyword
-    // is executed in a subexpression. More investigation required
-    // to remove the additional dependency
-    this.addDependency(obj);
+    this.init(label);
+    this.path = label;
+    this.sourceDep = this.addMutableDependency(source);
+    this.keyDep = this.addMutableDependency(keySource);
+    this.observedObject = null;
+    this.observedKey = null;
   };
 
-  GetStream.prototype = Object.create(Stream.prototype);
-
-  merge(GetStream.prototype, {
-    updateValueDependency() {
-      var pathValue = read(this.pathParam);
-
-      if (this.lastPathValue !== pathValue) {
-        if (typeof pathValue === 'string') {
-          this.valueDep.replace(this.objectParam.get(pathValue));
-        } else {
-          this.valueDep.replace();
-        }
+  DynamicKeyStream.prototype = Object.create(KeyStream.prototype);
 
-        this.lastPathValue = pathValue;
+  merge(DynamicKeyStream.prototype, {
+    key() {
+      const key = this.keyDep.getValue();
+      if (typeof key === 'string') {
+        Ember.assert('DynamicKeyStream error: key must not have a \'.\'', key.indexOf('.') === -1);
+        return key;
       }
     },
 
     compute() {
-      this.updateValueDependency();
-      return this.valueDep.getValue();
+      var object = this.sourceDep.getValue();
+      var key = this.key();
+      if (object && key) {
+        return get(object, key);
+      }
     },
 
     setValue(value) {
-      this.updateValueDependency();
-      this.valueDep.setValue(value);
-    }
+      var object = this.sourceDep.getValue();
+      var key = this.key();
+      if (object) {
+        set(object, key, value);
+      }
+    },
+
+    _super$revalidate: Stream.prototype.revalidate,
+
+    revalidate(value) {
+      this._super$revalidate(value);
+
+      var object = this.sourceDep.getValue();
+      var key = this.key();
+      if (object !== this.observedObject || key !== this.observedKey) {
+        this._clearObservedObject();
 
+        if (object && typeof object === 'object' && key) {
+          addObserver(object, key, this, this.notify);
+          this.observedObject = object;
+          this.observedKey = key;
+        }
+      }
+    },
+
+    _clearObservedObject() {
+      if (this.observedObject) {
+        removeObserver(this.observedObject, this.observedKey, this, this.notify);
+        this.observedObject = null;
+        this.observedKey = null;
+      }
+    }
   });
 }
 

packages/ember-htmlbars/lib/main.js

@@ -52,7 +52,6 @@ import concatHelper from 'ember-htmlbars/helpers/-concat';
 import joinClassesHelper from 'ember-htmlbars/helpers/-join-classes';
 import legacyEachWithControllerHelper from 'ember-htmlbars/helpers/-legacy-each-with-controller';
 import legacyEachWithKeywordHelper from 'ember-htmlbars/helpers/-legacy-each-with-keyword';
-import getHelper from 'ember-htmlbars/helpers/-get';
 import htmlSafeHelper from 'ember-htmlbars/helpers/-html-safe';
 import DOMHelper from 'ember-htmlbars/system/dom-helper';
 import Helper, { helper as makeHelper } from 'ember-htmlbars/helper';
@@ -79,9 +78,6 @@ registerHelper('concat', concatHelper);
 registerHelper('-join-classes', joinClassesHelper);
 registerHelper('-legacy-each-with-controller', legacyEachWithControllerHelper);
 registerHelper('-legacy-each-with-keyword', legacyEachWithKeywordHelper);
-if (isEnabled('ember-htmlbars-get-helper')) {
-  registerHelper('-get', getHelper);
-}
 registerHelper('-html-safe', htmlSafeHelper);
 
 Ember.HTMLBars = {