State Persistence

21 Jul 20164 minutes to read

TreeView state can be persisted by using ‘EnablePersistence’. In which user intractable model values only has been persisted in order to maintain performance.

The model values of below are maintained through id basis of tree node.

• selected
• checked
• expanded/ collapsed state

NOTE

In “UL” “li” template state has been persisted by index.

TreeView stores its model in local storage / cookies of browser before page refreshes and reinitialized with their stored model after refresh.

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

C#

public partial class TreeViewController : Controller
        {
            List<LoadData> treeData = new List<LoadData>();
            public ActionResult TreeViewFeatures()
            {
                treeData.Add(new LoadData { Id = 1, Parent = 0, Text = "Item 1" });
                treeData.Add(new LoadData { Id = 2, Parent = 0, Text = "Item 2" });
                treeData.Add(new LoadData { Id = 3, Parent = 0, Text = "Item 3" });
                treeData.Add(new LoadData { Id = 4, Parent = 0, Text = "Item 4" });
                treeData.Add(new LoadData { Id = 5, Parent = 1, Text = "Item 1.1" });
                treeData.Add(new LoadData { Id = 6, Parent = 1, Text = "Item 1.2" });
                treeData.Add(new LoadData { Id = 7, Parent = 1, Text = "Item 1.3" });
                treeData.Add(new LoadData { Id = 8, Parent = 3, Text = "Item 3.1" });
                treeData.Add(new LoadData { Id = 9, Parent = 3, Text = "Item 3.2" });
                treeData.Add(new LoadData { Id = 10, Parent = 5, Text = "Item 1.1.1" });
                ViewBag.datasource = treeData;
                return View();
            }
        }

In the view page, add TreeView helper with following properties.

RAZOR

@(Html.EJ().TreeView("treeViewDrag")
        .TreeViewFields(field =>
            field.Datasource((IEnumerable<LoadData>)ViewBag.datasource)
            .Id("Id")
            .ParentId("Parent")
            .Text("Text")
        )
        .EnablePersistence(true)
    )