Use a generic tree directive

You use Feather sfTree directive when you create a custom designer for your widgets. This directive enables you to display items hierarchically and provides you with the functionality to retrieve the selected item.

The sfTree is a directive with an isolated scope that is defined in a module with the same name: sfTree.

To enable AngularJs to link the sfTree directive in your custom designer view, you must load the script of the directive and add a dependency to the module.

Add generic tree directive

1. In your DesignerView.YourView.json file, add a scripts array. As a result, the file content should be similar to the following:

   {
      "priority": 1,
      "scripts": [
        "client-components/collections/sf-tree.js"
        ]
   }

2. In your designerview-yourview.js file, right before the definition of your custom view controller, place the following code snippet:

   var designerModule = angular.module('designer');
   angular.module('designer').requires.push('sfTree');

3. In your DesignerView.YourView.cshtml file, place the following tag where you want to render the sfTree directive:

  <sf-tree 
      sf-model="selectedItemId" 
      sf-request-children="requestChildrenCallback(parent)" 
      sf-identifier="Key" 
      sf-has-children-field="IsParent" 
      sf-expand-on-select/>

The **sfTree** directive exposes the following attributes:

* **sf-request-children**  
Accepts a callback function that must provide a promise with the array of items that are going to be displayed. The callback must return the root items or the child items of the currently selected node. The callback function is invoked during the initial load of the **sfTree** directive. The callback function is also invoked for each subsequent expansion if the child nodes of the selected item have not been retrieved yet.
* **sf-model**  
Accepts a scope variable that references the identifier field of the selected item. If there is no selected item, the value of this variable is **null**. 
* **sf-identifier**  
Specifies the property name of the selected item. If this attribute value is not explicitly specified, the **sfTree** uses the **Id** property by default.
* **sf-expand-on-select**  
Specifies whether the tree should be expanded when an item is selected.
* **sf-deselectable**  
Specifies whether the tree allows selected items to be deselected when they are clicked again. If an item is deselected, the value of the **sf-model** is set to **null**.
* **sf-template-url**  
Allows you to override the template of the tree.
* **sf-template-assembly**  
Specifies the assembly where the template of the tree is located.
* **sf-item-template-url**  
Allows you to override the item template of the tree.
* **sf-item-template-assembly**  
Specifies the assembly where the item template of the tree is located.
* **sf-has-children-field**  
Accepts the name of the scope variable that determines whether a node has children. If this attribute value is not explicitly specified, the **sfTree**  assumes that a node has children. When requesting the children of a node that has no children, an empty array is recieved as a response.

4. In your designer's controller, add the following code:

designerModule.controller('SettingsCtrl', ['$scope', '$q', function ($scope, $q) { $scope.requestChildrenCallback = function (parentObj) { parentObj = parentObj || {}; var parent = parentObj.IsParent; var result = $q.defer();

		if (!parent) {
			result.resolve([{ Key: '1', Title: 'Title Root 1', IsParent: true },
							{ Key: '2', Title: 'Root 2', IsParent: false }]);
		}
		else {
			result.resolve([{ Key: parentObj.Key + '#1', Title: '1st child of ' + parentObj.Key, IsParent: true },
							{ Key: parentObj.Key + '#2', Title: '2nd child of ' + parentObj.Key, IsParent: false }]);
		}

		return result.promise;
	};

}]); ``` The code above is invoked during the initial load of the sfTree directive and two root elements are added to the tree. If you select an item which is a parent, the tree expands and invokes the function. As a result, two more elements are added under the currently selected node. If the sf-has-children-field attribute is present, its scope variable is evaluated. If the attribute is not present, all elements of the tree visually appear as if they have children. If you try to expand such an element, the response is an empty array and the item no longer appears as a parent.

Subscribe to selection event

To provide notification when an item is selected the sfTree directive emits a custom selection event. To subscribe to the selection event, use the following code in your desinger's controller:

$scope.$on('sf-tree-item-selected', function (event, item) { });