Getting Started with EJ 1 ASP.NET MVC TreeView

23 Sep 2020 / 8 minutes to read

This section explains briefly about how to create a TreeView in ASP.NET MVC platform.

Create your first TreeView in MVC

Create a MVC Project and add necessary assemblies, CSS and scripts with the help of the given MVC-Getting Started documentation. After creating this project, you can create a TreeView in following ways.

TreeView using Helper element

You can create a tree using “Items” API of TreeView control. Here there is no necessary to use a data source for rendering TreeView.

In the view page, add TreeView helper as shown below. It will render the TreeView with specified items.

  • razor
  • @Html.EJ().TreeView("tree").Items(items =>
                    {
                        items.Add().Text("Item 1").Children(child =>
                        {
                            child.Add().Text("Item 1.1").Children(child1 =>
                            {
                                child1.Add().Text("Item 1.1.1");
                            });
                        });
                        items.Add().Text("Item 2").Children(child =>
                        {
                            child.Add().Text("Item 2.1");
                            child.Add().Text("Item 2.2");
                        });
                        items.Add().Text("Item 3").Children(child =>
                        {
                            child.Add().Text("Item 3.1");
                        });
                    })

    TreeView using Data Binding

    Another way of creating TreeView is binding with the data source, you can bind local data source to create a TreeView.

    The beforeLoad event will be triggered before loading nodes into TreeView.

    Render TreeView with local data source.

    In the model page, specify the TreeView node properties as shown below.

  • c#
  • public class LoadData
        {
            public int Id { get; set; }
            public int Parent { get; set; }
            public string Text { get; set; }
        }

    In the controller page, create a data list which contains the details about tree nodes.

  • c#
  • public partial class TreeViewController : Controller
        {
            List<LoadData> load = new List<LoadData>();
            public ActionResult TreeViewFeatures()
            {
                load.Add(new LoadData { Id = 1, Parent = 0, Text = "Item 1" });
                load.Add(new LoadData { Id = 2, Parent = 0, Text = "Item 2" });
                load.Add(new LoadData { Id = 3, Parent = 0, Text = "Item 3" });
                load.Add(new LoadData { Id = 4, Parent = 1, Text = "Item 1.1" });
                load.Add(new LoadData { Id = 5, Parent = 1, Text = "Item 1.2" });
                load.Add(new LoadData { Id = 6, Parent = 3, Text = "Item 3.1" });
                ViewBag.datasource = load;
                return View();
            }
        }

    Above data can be directly assigned to DataSource property and mapping data fields with respect to the mapper field in order to form TreeView.

  • razor
  • @(Html.EJ().TreeView("tree")
            .TreeViewFields(field =>
                field.Datasource((IEnumerable<LoadData>)ViewBag.datasource)
                .Id("Id")
                .ParentId("Parent")
                .Text("Text")
            )
        )

    Create Instance for TreeView

    You can create an instance for existing TreeView in following ways. Once a reference has been established, you can use the API’s of TreeView to control its behavior.

  • javascript
  • <script type="text/javascript">
            //Specify this after your TreeView creation
            //create instance for TreeView
            var treeObj = $("#treeView").ejTreeView('instance');
            //or
            var treeObj1 = $("#treeView").data("ejTreeView");
        </script>

    NOTE

    To configure the API settings after TreeView creation, please refer API configuration, Invoking Methods.

    TreeView events

    EJ MVC TreeView supports all the events which is available in EJ TreeView. Refer the following code example to specify an event using HTML helper of EJ MVC TreeView.

  • razor
  • @(Html.EJ().TreeView("treeView")
            .TreeViewFields(field =>
                field.Datasource((IEnumerable<LoadData>)ViewBag.datasource)
                .Id("Id")
                .ParentId("Parent")
                .Text("Text")
            )
            .ClientSideEvents(events =>
                events.NodeExpand("onNodeExpanded")
                .NodeCollapse("onNodeCollapsed")
                .NodeSelect("onNodeSelected")
            )
        )
        
        <script type="text/javascript">
            function onNodeCollapsed(args) {
                //Handle the node collapse event
            }
        
            function onNodeExpanded(args) {
                //Handle the node expand event
            }
        
            function onNodeSelected(args) {
                //Handle the node select event
            }
        </script>