Option to have a custom sort function

README.md

@@ -163,9 +163,12 @@ angular.module('demoApp').controller('sampleController', ['$nutrition', '$scope'
 | `mdOnReorder`  | `mdHead`   | `function`     | A callback function for when the order changes. The callback will receive the new order. |
 | `mdOrder`      | `mdHead`   | `string`       | A variable to bind the sort order to. |
 | `mdOrderBy`    | `mdColumn` | `string`       | The value to bind to the sort order. |
+| `mdCustomSort`    | `mdColumn` | `string`       | The custom function which translates data into values which can be ordered |
 
 When the user clicks the `md-column` element, the value of the `md-order-by` attribute will be bound to the variable provided to the `md-order` attribute on the `md-head` element. If the column is already sorted by that value, a minus sign `-` will be prefixed to the value. For most query languages, this is the universal symbol to sort descending.
 
+If the `md-custom-sort` element is used, the value of the `md-order-by` attribute will be bound to the function provided to `md-custom-sort`which will translate raw values to orderable values
+
 The variable can be used to send a query to the server or as the `orderBy` property of an `ng-repeat` expression.
 
 **Example Using ngRepeat**

src/scripts/mdColumn.js

@@ -48,6 +48,10 @@ function mdColumn($compile, $mdUtil) {
     function isActive() {
       return scope.orderBy && (headCtrl.order === scope.orderBy || headCtrl.order === '-' + scope.orderBy);
     }
+
+    function hasCustomSortFunc() {
+      return scope.customSortFunc;
+    }
 
     function isNumeric() {
       return attrs.mdNumeric === '' || scope.numeric;
@@ -56,9 +60,17 @@ function mdColumn($compile, $mdUtil) {
     function setOrder() {
       scope.$applyAsync(function () {
         if(isActive()) {
+          if (hasCustomSortFunc()) {
+            headCtrl.order = scope.customSortFunc;
+          } else {
           headCtrl.order = scope.getDirection() === 'md-asc' ? '-' + scope.orderBy : scope.orderBy;
+          }
         } else {
+          if (hasCustomSortFunc()) {
+            headCtrl.order = scope.customSortFunc;
+          } else {
           headCtrl.order = scope.getDirection() === 'md-asc' ? scope.orderBy : '-' + scope.orderBy;
+          }
         }
 
         if(angular.isFunction(headCtrl.onReorder)) {
@@ -121,8 +133,9 @@ function mdColumn($compile, $mdUtil) {
     scope: {
       numeric: '=?mdNumeric',
       orderBy: '@?mdOrderBy'
+      customSortFunc: '=?mdCustomSort'
     }
   };
 }
 
-mdColumn.$inject = ['$compile', '$mdUtil'];
+mdColumn.$inject = ['$compile', '$mdUtil'];