Coerce undefined to default when binding. Fixes #1742.

Polymer · Jun 24, 2015 · bc71099 · bc71099
1 parent f62a80d
commit bc71099
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Showing 4 changed files with 42 additions and 14 deletions.
diff --git a/src/standard/configure.html b/src/standard/configure.html
@@ -91,18 +91,26 @@
 
     _configureProperties: function(properties, config) {
       for (var i in properties) {
-        var c = properties[i];
-        if (c.value !== undefined) {
-          var value = c.value;
-          if (typeof value == 'function') {
-            // pass existing config values (this._config) to value function
-            value = value.call(this, this._config);
-          }
+        var value = this._defaultValueFromInfo(properties[i]);
+        if (value !== undefined) {
           config[i] = value;
         }
       }
     },
 
+    _defaultValueFromInfo: function(info) {
+      var value = info && info.value;
+      if (typeof value == 'function') {
+        // pass existing config values (this._config) to value function
+        value = value.call(this, this._config);
+      }
+      return value;
+    },
+
+    _defaultValueForProp: function(prop) {
+      return this._defaultValueFromInfo(this.getPropertyInfo(prop));
+    },
+
     _mixinConfigure: function(a, b) {
       for (var prop in b) {
         if (!this.getPropertyInfo(prop).readOnly) {

diff --git a/src/standard/effectBuilder.html b/src/standard/effectBuilder.html
@@ -263,6 +263,10 @@
             (node.localName == 'input' && property == 'value')) {
           value = value == undefined ? '' : value;
         }
+        // coerce undefined back to default
+        if (value === undefined && node._defaultValueForProp) {
+          value = node._defaultValueForProp(property);
+        }
         // TODO(kschaaf): Ideally we'd use `fromAbove: true`, but this
         // breaks read-only properties
         // this._setProperty(property, value, true, node);

diff --git a/test/unit/notify-path-elements.html b/test/unit/notify-path-elements.html
@@ -5,6 +5,10 @@
       notifyingValue: {
         type: Number,
         notify: true
+      },
+      valueWithDefault: {
+        type: Number,
+        value: 99
       }
     }
   });
@@ -50,7 +54,7 @@
       },
       objValueChanged: function(value) {
         this.observerCounts.objValueChanged++;
-        assert.equal(this.obj.value, value);
+        assert.equal(this.obj && this.obj.value, value);
       },
     });
   </script>
@@ -95,15 +99,15 @@
       },
       objValueChanged: function(value) {
         this.observerCounts.objValueChanged++;
-        assert.equal(this.obj.value, value);
+        assert.equal(this.obj && this.obj.value, value);
       },
     });
   </script>
 </dom-module>
 
 <dom-module id="x-stuff">
   <template>
-    <x-basic id="basic" notifying-value="{{nested.obj.value}}" attrvalue$="{{nested.obj.value}}"></x-basic>
+    <x-basic id="basic" notifying-value="{{nested.obj.value}}" value-with-default="{{nested.obj.value}}" attrvalue$="{{nested.obj.value}}"></x-basic>
     <x-compose id="compose" obj="{{nested.obj}}"></x-compose>
     <x-forward id="forward" obj="{{nested.obj}}"></x-forward>
     <div id="boundChild" computed-from-paths="{{computeFromPaths(a, nested.b, nested.obj.c)}}" array-length="{{data.length}}"></div>
@@ -157,11 +161,11 @@
       },
       nestedObjChanged: function(value) {
         this.observerCounts.nestedObjChanged++;
-        assert.equal(this.nested.obj, value);
+        assert.equal(this.nested && this.nested.obj, value);
       },
       nestedObjSubpathChanged: function(change) {
         this.observerCounts.nestedObjSubpathChanged++;
-        assert.equal(change.base, this.nested.obj);
+        assert.equal(change.base, this.nested && this.nested.obj);
         if (this.expectedNestedObjSubpath) {
           assert.equal(change.path, this.expectedNestedObjSubpath);
           assert.equal(change.value, this.expectedNestedObjValue);
@@ -175,12 +179,11 @@
         this.observerCounts.multipleChanged++;
         assert.equal(a, 'a');
         assert.equal(b, 'b');
-        assert.equal(nestedObjChange.base, this.nested.obj);
+        assert.equal(nestedObjChange.base, this.nested && this.nested.obj);
         if (this.expectedNestedObjSubpath) {
           assert.equal(nestedObjChange.path, this.expectedNestedObjSubpath);
           assert.equal(nestedObjChange.value, this.expectedNestedObjValue);
         }
-        assert.equal(nestedObjChange.base, this.nested.obj);
       },
       computeFromPaths: function(a, b, c) {
         assert.equal(a, this.a, 'computeFromNested `a` arg incorrect');

diff --git a/test/unit/notify-path.html b/test/unit/notify-path.html
@@ -75,6 +75,19 @@
     assert.equal(el.$.forward.$.compose.$.basic2.getAttribute('attrvalue'), '42');
   });
 
+  test('reset to default on null', function() {
+    // Setup
+    var nested = {
+      obj: {
+        value: 42
+      }
+    };
+    el.nested = nested;
+    assert.equal(el.$.basic.valueWithDefault, 42);
+    el.nested = null;
+    assert.equal(el.$.basic.valueWithDefault, 99);
+  });
+
   test('notification from basic element property change', function() {
     // Setup
     var nested = {