From db4a0552774f844ded8e01dc0ab04c2092716fa1 Mon Sep 17 00:00:00 2001
From: Rafael Weinstein <rafaelw@chromium.org>
Date: Mon, 13 Jan 2014 16:24:30 -0800
Subject: [PATCH] protect against undefined context in Member.valueFn

R=arv
BUG=https://github.com/Polymer/polymer-expressions/issues/19

Review URL: https://codereview.appspot.com/51750043
---
 src/polymer-expressions.js |  4 ++--
 tests/tests.js             | 18 ++++++++++++++++++
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/src/polymer-expressions.js b/src/polymer-expressions.js
index 21ac3f6..d1772a1 100644
--- a/src/polymer-expressions.js
+++ b/src/polymer-expressions.js
@@ -146,13 +146,13 @@
           if (path) {
             if (observer)
               observer.addPath(context, path);
-            return context[property.name];
+            return path.getValueFrom(context);
           }
 
           var propName = property(model, observer);
           if (observer)
             observer.addPath(context, propName);
-          return context[propName];
+          return context ? context[propName] : undefined;
         };
       }
       return this.valueFn_;
diff --git a/tests/tests.js b/tests/tests.js
index dcdf170..5aa5859 100644
--- a/tests/tests.js
+++ b/tests/tests.js
@@ -1602,6 +1602,24 @@ suite('PolymerExpressions', function() {
     });
   });
 
+  // https://github.com/Polymer/polymer-expressions/issues/19
+  test('issue-19', function(done) {
+    var div = createTestHtml(
+        '<template id="t" bind="{{ foo.bar as b }}">' +
+          '<span>{{ b }}</span>' +
+        '</template>');
+
+    var model = {};
+
+    recursivelySetTemplateModel(div, model);
+
+    then(function() {
+      var target = div.childNodes[1];
+
+      done();
+    });
+  });
+
   test('Non-model path expressions', function() {
     assert.isFalse(getExpression_('a + b').nonModelPath);
     assert.isFalse(getExpression_('a + b > 3 + hello["kitty"]').nonModelPath);