refact(ngOptions): specialize readValue and writeValue based on multiple attribute

Author: petebacondarwin

src/ng/directive/ngOptions.js

@@ -367,67 +367,70 @@ var ngOptionsDirective = ['$compile', '$parse', function($compile, $parse) {
 
 
       selectCtrl.writeValue = function writeNgOptionsValue(value) {
-        if (multiple) {
+        var option = options.getOptionFromViewValue(value);
 
-          options.items.forEach(function(option) {
-            option.element.selected = false;
-          });
+        if (option) {
+          if (selectElement[0].value !== option.selectValue) {
+            removeUnknownOption();
+            removeEmptyOption();
 
-          if (value) {
-            value.forEach(function(item) {
-              var option = options.getOptionFromViewValue(item);
-              if (option) option.element.selected = true;
-            });
+            selectElement[0].value = option.selectValue;
+            option.element.selected = true;
+            option.element.setAttribute('selected', 'selected');
           }
-
         } else {
-          var option = options.getOptionFromViewValue(value);
-
-          if (option) {
-            if (selectElement[0].value !== option.selectValue) {
-              removeUnknownOption();
-              removeEmptyOption();
-
-              selectElement[0].value = option.selectValue;
-              option.element.selected = true;
-              option.element.setAttribute('selected', 'selected');
-            }
+          if (value === null || providedEmptyOption) {
+            removeUnknownOption();
+            renderEmptyOption();
           } else {
-            if (value === null || providedEmptyOption) {
-              removeUnknownOption();
-              renderEmptyOption();
-            } else {
-              removeEmptyOption();
-              renderUnknownOption();
-            }
+            removeEmptyOption();
+            renderUnknownOption();
           }
         }
       };
 
-
       selectCtrl.readValue = function readNgOptionsValue() {
 
-        if (multiple) {
-
-          return selectElement.val().map(function(selectedKey) {
-            var option = options.selectValueMap[selectedKey];
-            return option.viewValue;
-          });
-
-        } else {
+        var selectedOption = options.selectValueMap[selectElement.val()];
 
-          var option = options.selectValueMap[selectElement.val()];
+        if (selectedOption) {
           removeEmptyOption();
           removeUnknownOption();
-          return option ? option.viewValue : null;
+          return selectedOption.viewValue;
         }
+        return null;
       };
 
 
+      // Update the controller methods for multiple selectable options
       if (multiple) {
+
         ngModelCtrl.$isEmpty = function(value) {
           return !value || value.length === 0;
         };
+
+
+        selectCtrl.writeValue = function writeNgOptionsMultiple(value) {
+          options.items.forEach(function(option) {
+            option.element.selected = false;
+          });
+
+          if (value) {
+            value.forEach(function(item) {
+              var option = options.getOptionFromViewValue(item);
+              if (option) option.element.selected = true;
+            });
+          }
+        };
+
+
+        selectCtrl.readValue = function readNgOptionsMultiple() {
+          var selectedValues = selectElement.val() || [];
+          return selectedValues.map(function(selectedKey) {
+            var option = options.selectValueMap[selectedKey];
+            return option.viewValue;
+          });
+        };
       }
 
 
@@ -590,7 +593,7 @@ var ngOptionsDirective = ['$compile', '$parse', function($compile, $parse) {
         ngModelCtrl.$render();
 
         // Check to see if the value has changed due to the update to the options
-        if(!ngModelCtrl.$isEmpty(previousValue)) {
+        if (!ngModelCtrl.$isEmpty(previousValue)) {
           var nextValue = selectCtrl.readValue();
           if (!equals(previousValue, nextValue)) {
             ngModelCtrl.$setViewValue(nextValue);