CheckBox in Blazor TreeView Component
26 Feb 202524 minutes to read
The Blazor TreeView component allows to check more than one node in TreeView by enabling the ShowCheckBox property. When this property is enabled, checkbox appears before each TreeView node text.
AutoCheck in Blazor TreeView Component
By default, the checkbox state of parent and child nodes are dependent on each other. For independent checked state, achieve it using the AutoCheck property.
- If not all child nodes are checked, the parent node will display as partially checked (intermediate state).
- If all child nodes are checked, the parent node will display as fully checked.
- When a parent node is checked, its child nodes will also display as checked.
@using Syncfusion.Blazor.Navigations
<SfTreeView TValue="MusicAlbum" ShowCheckBox="true" AutoCheck="true">
<TreeViewFieldsSettings TValue="MusicAlbum" Id="Id" DataSource="@Albums" Text="Name" ParentID="ParentId" HasChildren="HasChild" Expanded="Expanded" IsChecked="IsChecked"></TreeViewFieldsSettings>
</SfTreeView>
@code{
public class MusicAlbum
{
public int Id { get; set; }
public int? ParentId { get; set; }
public string? Name { get; set; }
public bool Expanded { get; set; }
public bool? IsChecked { get; set; }
public bool HasChild { get; set; }
}
List<MusicAlbum> Albums = new List<MusicAlbum>();
protected override void OnInitialized()
{
base.OnInitialized();
Albums.Add(new MusicAlbum
{
Id = 1,
Name = "Discover Music",
HasChild = true,
});
Albums.Add(new MusicAlbum
{
Id = 2,
ParentId = 1,
Name = "Hot Singles"
});
Albums.Add(new MusicAlbum
{
Id = 3,
ParentId = 1,
Name = "Rising Artists"
});
Albums.Add(new MusicAlbum
{
Id = 4,
ParentId = 1,
Name = "Live Music"
});
Albums.Add(new MusicAlbum
{
Id = 14,
HasChild = true,
Name = "MP3 Albums",
Expanded = true,
IsChecked = true
});
Albums.Add(new MusicAlbum
{
Id = 15,
ParentId = 14,
Name = "Rock"
});
Albums.Add(new MusicAlbum
{
Id = 16,
Name = "Gospel",
ParentId = 14,
});
Albums.Add(new MusicAlbum
{
Id = 17,
ParentId = 14,
Name = "Latin Music"
});
Albums.Add(new MusicAlbum
{
Id = 18,
ParentId = 14,
Name = "Jazz"
});
}
}
Check nodes through data binding
You can check a specific node by setting the IsChecked field to true for the corresponding node in the data source, which specifies the field for the checked state of the TreeView node.
@using Syncfusion.Blazor.Navigations
<SfTreeView TValue="MusicAlbum" ShowCheckBox="true" AutoCheck="true">
<TreeViewFieldsSettings TValue="MusicAlbum" Id="Id" DataSource="@Albums" Text="Name" ParentID="ParentId" HasChildren="HasChild" Expanded="Expanded" IsChecked="IsChecked"></TreeViewFieldsSettings>
</SfTreeView>
@code{
public class MusicAlbum
{
public int Id { get; set; }
public int? ParentId { get; set; }
public string? Name { get; set; }
public bool Expanded { get; set; }
public bool? IsChecked { get; set; }
public bool HasChild { get; set; }
}
List<MusicAlbum> Albums = new List<MusicAlbum>();
protected override void OnInitialized()
{
base.OnInitialized();
Albums.Add(new MusicAlbum
{
Id = 1,
Name = "Discover Music",
HasChild = true,
});
Albums.Add(new MusicAlbum
{
Id = 2,
ParentId = 1,
Name = "Hot Singles"
});
Albums.Add(new MusicAlbum
{
Id = 3,
ParentId = 1,
Name = "Rising Artists"
});
Albums.Add(new MusicAlbum
{
Id = 4,
ParentId = 1,
Name = "Live Music"
});
Albums.Add(new MusicAlbum
{
Id = 14,
HasChild = true,
Name = "MP3 Albums",
Expanded = true,
IsChecked = true
});
Albums.Add(new MusicAlbum
{
Id = 15,
ParentId = 14,
Name = "Rock"
});
Albums.Add(new MusicAlbum
{
Id = 16,
Name = "Gospel",
ParentId = 14,
});
Albums.Add(new MusicAlbum
{
Id = 17,
ParentId = 14,
Name = "Latin Music"
});
Albums.Add(new MusicAlbum
{
Id = 18,
ParentId = 14,
Name = "Jazz"
});
}
}Check nodes through API
The Blazor TreeView component enables the ability to check specific nodes upon initial rendering or dynamically through the two-way binding provided by the CheckedNodes property. This property allows for the checkbox selection of nodes by passing in an array collection of node IDs as strings.
@using Syncfusion.Blazor.Navigations
<SfTreeView TValue="MusicAlbum" ShowCheckBox="true" AutoCheck="true" @bind-CheckedNodes="CheckedNodes">
<TreeViewFieldsSettings TValue="MusicAlbum" Id="Id" DataSource="@Albums" Text="Name" ParentID="ParentId" HasChildren="HasChild" Expanded="Expanded" IsChecked="IsChecked"></TreeViewFieldsSettings>
</SfTreeView>
@code {
// Specifies the CheckedNodes value for TreeView component.
public string[] CheckedNodes = new string[] { "2", "4" };
public class MusicAlbum
{
public int Id { get; set; }
public int? ParentId { get; set; }
public string? Name { get; set; }
public bool Expanded { get; set; }
public bool? IsChecked { get; set; }
public bool HasChild { get; set; }
}
List<MusicAlbum> Albums = new List<MusicAlbum>();
protected override void OnInitialized()
{
base.OnInitialized();
Albums.Add(new MusicAlbum
{
Id = 1,
Name = "Discover Music",
HasChild = true,
Expanded = true
});
Albums.Add(new MusicAlbum
{
Id = 2,
ParentId = 1,
Name = "Hot Singles"
});
Albums.Add(new MusicAlbum
{
Id = 3,
ParentId = 1,
Name = "Rising Artists"
});
Albums.Add(new MusicAlbum
{
Id = 4,
ParentId = 1,
Name = "Live Music"
});
Albums.Add(new MusicAlbum
{
Id = 14,
HasChild = true,
Name = "MP3 Albums",
Expanded = true
});
Albums.Add(new MusicAlbum
{
Id = 15,
ParentId = 14,
Name = "Rock"
});
Albums.Add(new MusicAlbum
{
Id = 16,
Name = "Gospel",
ParentId = 14,
});
Albums.Add(new MusicAlbum
{
Id = 17,
ParentId = 14,
Name = "Latin Music"
});
Albums.Add(new MusicAlbum
{
Id = 18,
ParentId = 14,
Name = "Jazz"
});
}
}Check and Uncheck all nodes
The Blazor TreeView component offers the ability to check all unchecked nodes within the component by utilizing the CheckAllAsync method. Additionally, specific nodes can be selected by passing in an array of unchecked nodes. The UncheckAllAsync method also exists to uncheck all previously checked nodes within the component, and specific nodes can be deselected by passing in an array of checked nodes.
The example demonstrates the usage of these methods within the context of a button click event.
@using Syncfusion.Blazor.Navigations
@using Syncfusion.Blazor.Buttons
<SfButton OnClick="CheckAll">TreeView CheckAll</SfButton>
<SfButton OnClick="UncheckAll">TreeView UncheckAll</SfButton>
<SfTreeView TValue="MusicAlbum" @ref="treeview" ShowCheckBox="true" AutoCheck="true">
<TreeViewFieldsSettings TValue="MusicAlbum" Id="Id" DataSource="@Albums" Text="Name" ParentID="ParentId" HasChildren="HasChild" Expanded="Expanded" IsChecked="IsChecked"></TreeViewFieldsSettings>
</SfTreeView>
@code {
SfTreeView<MusicAlbum>? treeview;
public class MusicAlbum
{
public string? Id { get; set; }
public string? ParentId { get; set; }
public string? Name { get; set; }
public bool Expanded { get; set; }
public bool? IsChecked { get; set; }
public bool HasChild { get; set; }
}
List<MusicAlbum> Albums = new List<MusicAlbum>();
protected override void OnInitialized()
{
base.OnInitialized();
Albums.Add(new MusicAlbum
{
Id = "1",
Name = "Discover Music",
HasChild = true,
Expanded=true
});
Albums.Add(new MusicAlbum
{
Id = "2",
ParentId = "1",
Name = "Hot Singles"
});
Albums.Add(new MusicAlbum
{
Id = "3",
ParentId = "1",
Name = "Rising Artists"
});
Albums.Add(new MusicAlbum
{
Id = "4",
ParentId = "1",
Name = "Live Music"
});
Albums.Add(new MusicAlbum
{
Id = "04",
HasChild = true,
Name = "MP3 Albums",
Expanded = true
});
Albums.Add(new MusicAlbum
{
Id = "5",
ParentId = "04",
Name = "Rock"
});
Albums.Add(new MusicAlbum
{
Id = "6",
Name = "Gospel",
ParentId = "04",
});
Albums.Add(new MusicAlbum
{
Id = "7",
ParentId = "04",
Name = "Latin Music"
});
Albums.Add(new MusicAlbum
{
Id = "8",
ParentId = "04",
Name = "Jazz"
});
}
public void CheckAll()
{
// To check all the nodes in the TreeView
this.treeview.CheckAllAsync();
// To check the particular node in the TreeView
// this.treeview.CheckAllAsync(new string[]{"1"});
}
public void UncheckAll()
{
// To uncheck all the nodes in the TreeView
this.treeview.UncheckAllAsync();
// To uncheck the particular node in the TreeView
// this.treeview.UncheckAllAsync(new string[]{"1"});
}
}Get checked nodes
The Blazor TreeView component provides the capability to pre-select specific nodes during initialization through the use of the CheckedNodes property. Additionally, the component offers the GetTreeData method, which allows for retrieval of the updated data source and subsequent refreshing of the TreeView. By passing the CheckedNodes of specific TreeView nodes as arguments to this method, the updated data source of only those nodes will be returned. If no arguments are passed, the entire updated data source of the TreeView will be returned.
@using Syncfusion.Blazor.Navigations
<div class="control_wrapper">
<SfTreeView TValue="MusicAlbum" @ref="TreeRef" ShowCheckBox="true" @bind-CheckedNodes="@CheckedNodes">
<TreeViewFieldsSettings TValue="MusicAlbum" Id="Id" DataSource="@Albums" Text="Name" ParentID="ParentId" HasChildren="HasChild" Expanded="Expanded" IsChecked="IsChecked"></TreeViewFieldsSettings>
</SfTreeView>
</div>
<div class="col-lg-4 property-section property-custom">
<div class="property-panel-section">
<div class="property-panel-header">Checked Items</div>
<div id="selecttable" class="property-panel-content">
<table id="property" title="Properties" class="property-panel-table">
<thead>
<tr>
<th style="width: 50%">Id</th>
<th style="width: 50%;">Text</th>
</tr>
</thead>
<tbody>
@if (TreeRef != null)
{
@for (int i = 0; i < CheckedNodes?.Length; i++)
{
List<MusicAlbum> tree = TreeRef.GetTreeData(CheckedNodes[i]);
<tr>
<td style="width: 30%">
<div>@tree[0].Id</div>
</td>
<td style="width: 30%">
<div>@tree[0].Name</div>
</td>
</tr>
}
}
</tbody>
</table>
</div>
</div>
</div>
@code {
// Specify the reference of TreeView element.
SfTreeView<MusicAlbum>? TreeRef;
// Specifies the CheckedNodes value for TreeView component.
public string[] CheckedNodes = new string[] { "2", "4" };
public class MusicAlbum
{
public string? Id { get; set; }
public int? ParentId { get; set; }
public string? Name { get; set; }
public bool Expanded { get; set; }
public bool? IsChecked { get; set; }
public bool HasChild { get; set; }
}
List<MusicAlbum> Albums = new List<MusicAlbum>();
protected override void OnAfterRender(bool firstRender)
{
if (firstRender)
{
StateHasChanged();
}
}
protected override void OnInitialized()
{
base.OnInitialized();
Albums.Add(new MusicAlbum
{
Id = "1",
Name = "Discover Music",
HasChild = true,
Expanded = true
});
Albums.Add(new MusicAlbum
{
Id = "2",
ParentId = 1,
Name = "Hot Singles"
});
Albums.Add(new MusicAlbum
{
Id = "3",
ParentId = 1,
Name = "Rising Artists"
});
Albums.Add(new MusicAlbum
{
Id = "4",
ParentId = 1,
Name = "Live Music"
});
Albums.Add(new MusicAlbum
{
Id = "14",
HasChild = true,
Name = "MP3 Albums",
Expanded = true
});
Albums.Add(new MusicAlbum
{
Id = "15",
ParentId = 14,
Name = "Rock"
});
Albums.Add(new MusicAlbum
{
Id = "16",
Name = "Gospel",
ParentId = 14,
});
Albums.Add(new MusicAlbum
{
Id = "17",
ParentId = 14,
Name = "Latin Music"
});
Albums.Add(new MusicAlbum
{
Id = "18",
ParentId = 14,
Name = "Jazz"
});
}
}
<style>
.control_wrapper {
max-width: 500px;
border: 1px solid #dddddd;
border-radius: 3px;
max-height: 470px;
overflow: auto;
}
.col-lg-4.property-section.property-custom{
border: 1px solid #dddddd;
padding: 15px;
}
#selecttable {
overflow: auto;
max-height: 420px;
}
#selecttable div {
padding-left: 0;
}
</style>
Single selection with CheckBox
The Blazor TreeView component allows for single selection of nodes with checkboxes by utilizing the UncheckAllAsync method during the NodeChecking event to uncheck previously checked nodes.
@using Syncfusion.Blazor.Navigations
<SfTreeView TValue="MusicAlbum" ShowCheckBox="true" AutoCheck="true" @ref="tree">
<TreeViewEvents TValue="MusicAlbum" NodeChecking="NodeChecking"></TreeViewEvents>
<TreeViewFieldsSettings TValue="MusicAlbum" Id="Id" DataSource="@Albums" Text="Name" ParentID="ParentId" HasChildren="HasChild" Expanded="Expanded" IsChecked="IsChecked"></TreeViewFieldsSettings>
</SfTreeView>
@code{
SfTreeView<MusicAlbum>? tree;
public class MusicAlbum
{
public int Id { get; set; }
public int? ParentId { get; set; }
public string? Name { get; set; }
public bool Expanded { get; set; }
public bool? IsChecked { get; set; }
public bool HasChild { get; set; }
}
public void NodeChecking(NodeCheckEventArgs args)
{
if(args.Action=="check" && args.IsInteracted)
{
this.tree.UncheckAllAsync();
}
}
List<MusicAlbum> Albums = new List<MusicAlbum>();
protected override void OnInitialized()
{
base.OnInitialized();
Albums.Add(new MusicAlbum
{
Id = 1,
Name = "Discover Music",
HasChild = true,
Expanded = true
});
Albums.Add(new MusicAlbum
{
Id = 2,
ParentId = 1,
Name = "Hot Singles"
});
Albums.Add(new MusicAlbum
{
Id = 3,
ParentId = 1,
Name = "Rising Artists"
});
Albums.Add(new MusicAlbum
{
Id = 4,
ParentId = 1,
Name = "Live Music"
});
Albums.Add(new MusicAlbum
{
Id = 14,
HasChild = true,
Name = "MP3 Albums",
Expanded = true
});
Albums.Add(new MusicAlbum
{
Id = 15,
ParentId = 14,
Name = "Rock"
});
Albums.Add(new MusicAlbum
{
Id = 16,
Name = "Gospel",
ParentId = 14,
});
Albums.Add(new MusicAlbum
{
Id = 17,
ParentId = 14,
Name = "Latin Music"
});
Albums.Add(new MusicAlbum
{
Id = 18,
ParentId = 14,
Name = "Jazz"
});
}
}Hide CheckBox for parent nodes
The Blazor TreeView component allows for the rendering of checkboxes before each node by enabling the ShowCheckBox property. However, if the application requires checkboxes to only be rendered for child nodes, the checkbox for the parent node can be removed by customizing the CSS.
@using Syncfusion.Blazor.Navigations
<SfTreeView TValue="Country" ShowCheckBox="true" CssClass="customTree">
<TreeViewFieldsSettings TValue="Country" Id="Id" DataSource="@Countries" Text="Name" ParentID="ParentId" HasChildren="HasChild" Expanded="Expanded" Selected="IsSelected"></TreeViewFieldsSettings>
</SfTreeView>
@code{
public class Country
{
public int Id { get; set; }
public int? ParentId { get; set; }
public string? Name { get; set; }
public bool HasChild { get; set; }
public bool Expanded { get; set; }
public bool IsSelected { get; set; }
}
List<Country> Countries = new List<Country>();
protected override void OnInitialized()
{
base.OnInitialized();
Countries.Add(new Country
{
Id = 1,
Name = "Australia",
HasChild = true,
Expanded = true
});
Countries.Add(new Country
{
Id = 2,
ParentId = 1,
Name = "New South Wales",
IsSelected = true
});
Countries.Add(new Country
{
Id = 3,
ParentId = 1,
Name = "Victoria",
IsSelected = true
});
Countries.Add(new Country
{
Id = 4,
ParentId = 1,
Name = "South Australia"
});
Countries.Add(new Country
{
Id = 5,
ParentId = 1,
Name = "Western Australia"
});
Countries.Add(new Country
{
Id = 6,
Name = "Brazil",
HasChild = true
});
Countries.Add(new Country
{
Id = 7,
ParentId = 6,
Name = "Paraná"
});
Countries.Add(new Country
{
Id = 8,
ParentId = 6,
Name = "Ceará"
});
Countries.Add(new Country
{
Id = 9,
Name = "China",
HasChild = true
});
Countries.Add(new Country
{
Id = 10,
ParentId = 9,
Name = "Guangzhou"
});
Countries.Add(new Country
{
Id = 11,
ParentId = 9,
Name = "Shantou"
});
}
}
<style>
.customTree .e-list-item.e-level-1 .e-text-content.e-icon-wrapper
.e-checkbox-wrapper {
display: none
}
</style>
Cancel the check action
The Blazor TreeView component offers the ability to cancel the check action by setting the Cancel argument value as true within the NodeChecking event. This will prevent the check action from occurring within the TreeView component.
@using Syncfusion.Blazor.Navigations
<SfTreeView TValue="MusicAlbum" ShowCheckBox="true" AutoCheck="true">
<TreeViewEvents TValue="MusicAlbum" NodeChecking="NodeChecking"></TreeViewEvents>
<TreeViewFieldsSettings TValue="MusicAlbum" Id="Id" DataSource="@Albums" Text="Name" ParentID="ParentId" HasChildren="HasChild" Expanded="Expanded" IsChecked="IsChecked"></TreeViewFieldsSettings>
</SfTreeView>
@code {
public class MusicAlbum
{
public int Id { get; set; }
public int? ParentId { get; set; }
public string? Name { get; set; }
public bool Expanded { get; set; }
public bool? IsChecked { get; set; }
public bool HasChild { get; set; }
}
public void NodeChecking(NodeCheckEventArgs args)
{
args.Cancel = true;
}
List<MusicAlbum> Albums = new List<MusicAlbum>();
protected override void OnInitialized()
{
base.OnInitialized();
Albums.Add(new MusicAlbum
{
Id = 1,
Name = "Discover Music",
HasChild = true,
Expanded = true
});
Albums.Add(new MusicAlbum
{
Id = 2,
ParentId = 1,
Name = "Hot Singles"
});
Albums.Add(new MusicAlbum
{
Id = 3,
ParentId = 1,
Name = "Rising Artists"
});
Albums.Add(new MusicAlbum
{
Id = 4,
ParentId = 1,
Name = "Live Music"
});
Albums.Add(new MusicAlbum
{
Id = 14,
HasChild = true,
Name = "MP3 Albums",
Expanded = true
});
Albums.Add(new MusicAlbum
{
Id = 15,
ParentId = 14,
Name = "Rock"
});
Albums.Add(new MusicAlbum
{
Id = 16,
Name = "Gospel",
ParentId = 14,
});
Albums.Add(new MusicAlbum
{
Id = 17,
ParentId = 14,
Name = "Latin Music"
});
Albums.Add(new MusicAlbum
{
Id = 18,
ParentId = 14,
Name = "Jazz"
});
}
}