added support in column order

Author: LironT

README.md

@@ -53,6 +53,7 @@ ngCsv attributes
   <button type="button" ng-csv="getArray()" csv-header="['Field A', 'Field B', 'Field C']" filename="test.csv">Export</button>
   ```
 
+* csv-column-order: Defines the column order to be set when creating the body of the CSV (may be according to the csv-headers) - use it when you have an array of objects.
 * field-separator: Defines the field separator character (default is ,)
 * decimal-separator: Defines the decimal separator character (default is .). If set to "locale", it uses the [language sensitive representation of the number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/toLocaleString).
 * text-delimiter: If provided, will use this characters to "escape" fields, otherwise will use double quotes as deafult

src/ng-csv/directives/ng-csv.js

@@ -12,6 +12,7 @@ angular.module('ngCsv.directives').
         data: '&ngCsv',
         filename: '@filename',
         header: '&csvHeader',
+        columnOrder: '&csvColumnOrder',
         txtDelim: '@textDelimiter',
         decimalSep: '@decimalSeparator',
         quoteStrings: '@quoteStrings',
@@ -49,7 +50,7 @@ angular.module('ngCsv.directives').
               addByteOrderMarker: $scope.addByteOrderMarker
             };
             if (angular.isDefined($attrs.csvHeader)) options.header = $scope.$eval($scope.header);
-
+            if (angular.isDefined($attrs.csvColumnOrder)) options.columnOrder = $scope.$eval($scope.columnOrder);
 
             options.fieldSep = $scope.fieldSep ? $scope.fieldSep : ",";
 

src/ng-csv/services/csv-service.js

@@ -102,8 +102,10 @@ angular.module('ngCsv.services').
 
           infoArray = [];
 
-          angular.forEach(row, function (field, key) {
-            this.push(that.stringifyField(field, options));
+          var iterator = !!options.columnOrder ? options.columnOrder : row;
+          angular.forEach(iterator, function (field, key) {
+            var val = !!options.columnOrder ? row[field] : field;
+            this.push(that.stringifyField(val, options));
           }, infoArray);
 
           dataString = infoArray.join(options.fieldSep ? options.fieldSep : ",");