title: UI Grid: Get value of row before saving edits
body: <p>I need to get the original value of a row when someone starts to edit it.</p>
  
  <p>Guess the beginEditCell method of <a href="http://ui-grid.info/docs/#/api/ui.grid.edit.service:uiGridEditService" rel="nofollow">http://ui-grid.info/docs/#/api/ui.grid.edit.service:uiGridEditService</a> is doing exactly that. But I have no clue how to implement it.</p>
  
  <p>This is how I call a function when the row is being saved.</p>
  
  <pre><code>$scope.users.onRegisterApi = function(gridApi){
  
      // Set gridApi on scope
      $scope.gridApi = gridApi;
  
      // Call $scope.saveRow after finishing editing row
      gridApi.rowEdit.on.saveRow($scope, $scope.saveRow);
  };
  </code></pre>
  
  <p>So I assume .beginEditCell() needs to be called before .saveRow, but I don't get how.</p>