fix(ngRequired): set invalid to false if select value is required (value is not in options)

Author: m-amr

src/ng/directive/ngOptions.js

@@ -728,6 +728,39 @@ var ngOptionsDirective = ['$compile', '$parse', function($compile, $parse) {
         });
         removeExcessElements(currentElement);
 
+        ngModelCtrl.$validators.required = function(modelValue, viewValue) {
+
+          if (!attr.required) {
+            return true;
+          } else if (ngModelCtrl.$isEmpty(viewValue)) {
+            return false;
+          }
+
+          var isValidOption = true;
+          var viewOptions = [];
+          // Get all option and add them to viewOptions array
+          angular.forEach(options.items, function(item) {
+            viewOptions.push(options.getViewValueFromOption(item));
+          });
+
+          // In case of multiple view model is an array so validate all view values
+          // if one of them doesn't match set isValidOption to false
+          if (multiple && viewValue) {
+            for (var i = 0, length = viewValue.length; i < length; i++) {
+              if (viewOptions.indexOf(viewValue[i]) === -1) {
+                isValidOption = false;
+                 break;
+              }
+            }
+          } else {
+            if (viewOptions.indexOf(viewValue) === -1) {
+              isValidOption = false;
+            }
+          }
+
+          return isValidOption;
+        };
+
         ngModelCtrl.$render();
 
         // Check to see if the value has changed due to the update to the options