Getting Started with Blazor TreeGrid Component

19 Jun 202421 minutes to read

This section briefly explains about how to include Blazor TreeGrid component in your Blazor Server App and Blazor WebAssembly App using Visual Studio.

Prerequisites

Create a new Blazor App in Visual Studio

You can create a Blazor Server App or Blazor WebAssembly App using Visual Studio via Microsoft Templates or the Syncfusion Blazor Extension.

Install Syncfusion Blazor TreeGrid and Themes NuGet in the App

To add Blazor TreeGrid component in the app, open the NuGet package manager in Visual Studio (Tools → NuGet Package Manager → Manage NuGet Packages for Solution), search and install Syncfusion.Blazor.TreeGrid and Syncfusion.Blazor.Themes. Alternatively, you can utilize the following package manager command to achieve the same.

Install-Package Syncfusion.Blazor.TreeGrid -Version 27.1.48
Install-Package Syncfusion.Blazor.Themes -Version 27.1.48

NOTE

Syncfusion Blazor components are available in nuget.org. Refer to NuGet packages topic for available NuGet packages list with component details.

Register Syncfusion Blazor Service

Open ~/_Imports.razor file and import the Syncfusion.Blazor and Syncfusion.Blazor.TreeGrid namespace.

@using Syncfusion.Blazor
@using Syncfusion.Blazor.TreeGrid

Now, register the Syncfusion Blazor Service in the ~/Program.cs file of your Blazor Server App or Blazor WebAssembly App.

using Microsoft.AspNetCore.Components;
using Microsoft.AspNetCore.Components.Web;
using Syncfusion.Blazor;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.AddRazorPages();
builder.Services.AddServerSideBlazor();
builder.Services.AddSyncfusionBlazor();

var app = builder.Build();
....
using Microsoft.AspNetCore.Components.Web;
using Microsoft.AspNetCore.Components.WebAssembly.Hosting;
using Syncfusion.Blazor;

var builder = WebAssemblyHostBuilder.CreateDefault(args);
builder.RootComponents.Add<App>("#app");
builder.RootComponents.Add<HeadOutlet>("head::after");

builder.Services.AddScoped(sp => new HttpClient { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) });

builder.Services.AddSyncfusionBlazor();
await builder.Build().RunAsync();
....

Add stylesheet and script resources

The theme stylesheet and script can be accessed from NuGet through Static Web Assets. Reference the stylesheet and script in the <head> of the main page as follows:

  • For .NET 6 Blazor Server app, include it in ~/Pages/_Layout.cshtml file.

  • For .NET 7 Blazor Server app, include it in the ~/Pages/_Host.cshtml file.

  • For Blazor WebAssembly app, include it in the ~/index.html file.

<head>
    ....
    <link href="_content/Syncfusion.Blazor.Themes/bootstrap5.css" rel="stylesheet" />
    <script src="_content/Syncfusion.Blazor.Core/scripts/syncfusion-blazor.min.js" type="text/javascript"></script>
</head>

NOTE

Check out the Blazor Themes topic to discover various methods (Static Web Assets, CDN, and CRG) for referencing themes in your Blazor application. Also, check out the Adding Script Reference topic to learn different approaches for adding script references in your Blazor application.

Add Blazor TreeGrid component

Add the Syncfusion Blazor TreeGrid component in the ~/Pages/Index.razor file.

<SfTreeGrid DataSource="@TreeData" IdMapping="TaskId" ParentIdMapping="ParentId" TreeColumnIndex="1">
    <TreeGridColumns>
        <TreeGridColumn Field="TaskId" HeaderText="Task ID" Width="5" TextAlign="Syncfusion.Blazor.Grids.TextAlign.Center"></TreeGridColumn>
        <TreeGridColumn Field="TaskName" HeaderText="Task Name" Width="30" TextAlign="Syncfusion.Blazor.Grids.TextAlign.Center"></TreeGridColumn>
    </TreeGridColumns>
</SfTreeGrid>

@code
{
    public class BusinessObject
    {
        public int TaskId { get; set; }
        public string TaskName { get; set; }
        public int? ParentId { get; set; }
    }

    public List<BusinessObject> TreeData = new List<BusinessObject>();

    protected override void OnInitialized()
    {
        TreeData.Add(new BusinessObject() { TaskId = 1, TaskName = "Parent Task 1", ParentId = null });
        TreeData.Add(new BusinessObject() { TaskId = 2, TaskName = "Child task 1", ParentId = 1 });
        TreeData.Add(new BusinessObject() { TaskId = 3, TaskName = "Child Task 2", ParentId = 1, });
        TreeData.Add(new BusinessObject() { TaskId = 4, TaskName = "Parent Task 2", ParentId = null });
        TreeData.Add(new BusinessObject() { TaskId = 5, TaskName = "Child Task 5", ParentId = 4 });
        TreeData.Add(new BusinessObject() { TaskId = 6, TaskName = "Child Task 6", ParentId = 5 });
    }
}
  • Press Ctrl+F5 (Windows) or ⌘+F5 (macOS) to launch the application. This will render the Syncfusion Blazor TreeGrid component in your default web browser.
Blazor TreeGrid

Defining columns

The Tree Grid has an option to define columns using the TreeGridColumns directive. In the TreeGridColumn directive there are properties to customize columns.

Let’s check the properties used here:

  • Field to map with a property name in datasource is been added.
  • HeaderText to change the title of columns is been added.
  • TextAlign to change the alignment of columns is been used. By default, columns will be left aligned. To change columns to right align, define TextAlign as Right.
<SfTreeGrid DataSource="@TreeData" IdMapping="TaskId" ParentIdMapping="ParentId" TreeColumnIndex="1">
    <TreeGridColumns>
        <TreeGridColumn Field="TaskId" HeaderText="Task ID" Width="80" TextAlign="Syncfusion.Blazor.Grids.TextAlign.Right"></TreeGridColumn>
        <TreeGridColumn Field="TaskName" HeaderText="Task Name" Width="160"></TreeGridColumn>
        <TreeGridColumn Field="Duration" HeaderText="Duration" Width="100" TextAlign="Syncfusion.Blazor.Grids.TextAlign.Right"></TreeGridColumn>
        <TreeGridColumn Field="Progress" HeaderText="Progress" Width="100" TextAlign="Syncfusion.Blazor.Grids.TextAlign.Right"></TreeGridColumn>
        <TreeGridColumn Field="Priority" HeaderText="Priority" Width="80"></TreeGridColumn>
    </TreeGridColumns>
</SfTreeGrid>

@code{

    public class BusinessObject
    {
        public int TaskId { get; set; }
        public string TaskName { get; set; }
        public int Duration { get; set; }
        public int Progress { get; set; }
        public string Priority { get; set; }
        public int? ParentId { get; set; }
    }

    public List<BusinessObject> TreeData = new List<BusinessObject>();

    protected override void OnInitialized()
    {
        TreeData.Add(new BusinessObject() { TaskId = 1, TaskName = "Parent Task 1", Duration = 10, Progress = 70, ParentId = null, Priority = "High" });
        TreeData.Add(new BusinessObject() { TaskId = 2, TaskName = "Child task 1", Duration = 4, Progress = 80, ParentId = 1, Priority = "Normal" });
        TreeData.Add(new BusinessObject() { TaskId = 3, TaskName = "Child Task 2", Duration = 5, Progress = 65, ParentId = 1, Priority = "Critical" });
        TreeData.Add(new BusinessObject() { TaskId = 4, TaskName = "Parent Task 2", Duration = 6, Progress = 77, ParentId = null, Priority = "Low" });
        TreeData.Add(new BusinessObject() { TaskId = 5, TaskName = "Child Task 5", Duration = 9, Progress = 25, ParentId = 4, Priority = "Normal" });
        TreeData.Add(new BusinessObject() { TaskId = 6, TaskName = "Child Task 6", Duration = 9, Progress = 7, ParentId = 5, Priority = "Normal" });
        TreeData.Add(new BusinessObject() { TaskId = 7, TaskName = "Parent Task 3", Duration = 4, Progress = 45, ParentId = null, Priority = "High" });
        TreeData.Add(new BusinessObject() { TaskId = 8, TaskName = "Child Task 7", Duration = 3, Progress = 38, ParentId = 7, Priority = "Critical" });
        TreeData.Add(new BusinessObject() { TaskId = 9, TaskName = "Child Task 8", Duration = 7, Progress = 70, ParentId = 7, Priority = "Low" });
    }
}

In the above code example, the Self-Referential data binding is represented in which the IdMapping and ParentIdMapping properties denotes the hierarchy relationship; whereas in Hierarchical data binding ChildMapping denotes the hierarchy relationship.

Enable paging

The paging feature enables users to view the tree grid record in a paged view. It can be enabled by setting the AllowPaging property to true. The pager can be customized using the PageSettings property.

In root-level paging mode, paging is based on the root-level rows only, i.e., it ignores the child row count and it can be enabled by using the PageSettings.PageSizeMode property.

<SfTreeGrid DataSource="@TreeData" IdMapping="TaskId" ParentIdMapping="ParentId" TreeColumnIndex="1" AllowPaging="true">
    <TreeGridPageSettings PageSizeMode="PageSizeMode.Root" PageSize="2"></TreeGridPageSettings>
    <TreeGridColumns>
        <TreeGridColumn Field="TaskId" HeaderText="Task ID" Width="80" TextAlign="Syncfusion.Blazor.Grids.TextAlign.Right"></TreeGridColumn>
        <TreeGridColumn Field="TaskName" HeaderText="Task Name" Width="160"></TreeGridColumn>
        <TreeGridColumn Field="Duration" HeaderText="Duration" Width="100" TextAlign="Syncfusion.Blazor.Grids.TextAlign.Right"></TreeGridColumn>
        <TreeGridColumn Field="Progress" HeaderText="Progress" Width="100" TextAlign="Syncfusion.Blazor.Grids.TextAlign.Right"></TreeGridColumn>
        <TreeGridColumn Field="Priority" HeaderText="Priority" Width="80"></TreeGridColumn>
    </TreeGridColumns>
</SfTreeGrid>

@code{

    public class BusinessObject
    {
        public int TaskId { get; set; }
        public string TaskName { get; set; }
        public int Duration { get; set; }
        public int Progress { get; set; }
        public string Priority { get; set; }
        public int? ParentId { get; set; }
    }

    public List<BusinessObject> TreeData = new List<BusinessObject>();

    protected override void OnInitialized()
    {
        TreeData.Add(new BusinessObject() { TaskId = 1, TaskName = "Parent Task 1", Duration = 10, Progress = 70, ParentId = null, Priority = "High" });
        TreeData.Add(new BusinessObject() { TaskId = 2, TaskName = "Child task 1", Duration = 4, Progress = 80, ParentId = 1, Priority = "Normal" });
        TreeData.Add(new BusinessObject() { TaskId = 3, TaskName = "Child Task 2", Duration = 5, Progress = 65, ParentId = 1, Priority = "Critical" });
        TreeData.Add(new BusinessObject() { TaskId = 4, TaskName = "Parent Task 2", Duration = 6, Progress = 77, ParentId = null, Priority = "Low" });
        TreeData.Add(new BusinessObject() { TaskId = 5, TaskName = "Child Task 5", Duration = 9, Progress = 25, ParentId = 4, Priority = "Normal" });
        TreeData.Add(new BusinessObject() { TaskId = 6, TaskName = "Child Task 6", Duration = 9, Progress = 7, ParentId = 5, Priority = "Normal" });
        TreeData.Add(new BusinessObject() { TaskId = 7, TaskName = "Parent Task 3", Duration = 4, Progress = 45, ParentId = null, Priority = "High" });
        TreeData.Add(new BusinessObject() { TaskId = 8, TaskName = "Child Task 7", Duration = 3, Progress = 38, ParentId = 7, Priority = "Critical" });
        TreeData.Add(new BusinessObject() { TaskId = 9, TaskName = "Child Task 8", Duration = 7, Progress = 70, ParentId = 7, Priority = "Low" });
    }
}

Enable sorting

The sorting feature enables to order the records. It can be enabled by setting the AllowSorting property to true.

<SfTreeGrid DataSource="@TreeData" IdMapping="TaskId" ParentIdMapping="ParentId" TreeColumnIndex="1" AllowPaging="true" AllowSorting="true">
    <TreeGridPageSettings PageSizeMode="PageSizeMode.Root" PageSize="2"></TreeGridPageSettings>
    <TreeGridColumns>
        <TreeGridColumn Field="TaskId" HeaderText="Task ID" Width="80" TextAlign="Syncfusion.Blazor.Grids.TextAlign.Right"></TreeGridColumn>
        <TreeGridColumn Field="TaskName" HeaderText="Task Name" Width="160"></TreeGridColumn>
        <TreeGridColumn Field="Duration" HeaderText="Duration" Width="100" TextAlign="Syncfusion.Blazor.Grids.TextAlign.Right"></TreeGridColumn>
        <TreeGridColumn Field="Progress" HeaderText="Progress" Width="100" TextAlign="Syncfusion.Blazor.Grids.TextAlign.Right"></TreeGridColumn>
        <TreeGridColumn Field="Priority" HeaderText="Priority" Width="80"></TreeGridColumn>
    </TreeGridColumns>
</SfTreeGrid>

@code{

    public class BusinessObject
    {
        public int TaskId { get; set; }
        public string TaskName { get; set; }
        public int Duration { get; set; }
        public int Progress { get; set; }
        public string Priority { get; set; }
        public int? ParentId { get; set; }
    }

    public List<BusinessObject> TreeData = new List<BusinessObject>();

    protected override void OnInitialized()
    {
        TreeData.Add(new BusinessObject() { TaskId = 1, TaskName = "Parent Task 1", Duration = 10, Progress = 70, ParentId = null, Priority = "High" });
        TreeData.Add(new BusinessObject() { TaskId = 2, TaskName = "Child task 1", Duration = 4, Progress = 80, ParentId = 1, Priority = "Normal" });
        TreeData.Add(new BusinessObject() { TaskId = 3, TaskName = "Child Task 2", Duration = 5, Progress = 65, ParentId = 1, Priority = "Critical" });
        TreeData.Add(new BusinessObject() { TaskId = 4, TaskName = "Parent Task 2", Duration = 6, Progress = 77, ParentId = null, Priority = "Low" });
        TreeData.Add(new BusinessObject() { TaskId = 5, TaskName = "Child Task 5", Duration = 9, Progress = 25, ParentId = 4, Priority = "Normal" });
        TreeData.Add(new BusinessObject() { TaskId = 6, TaskName = "Child Task 6", Duration = 9, Progress = 7, ParentId = 5, Priority = "Normal" });
        TreeData.Add(new BusinessObject() { TaskId = 7, TaskName = "Parent Task 3", Duration = 4, Progress = 45, ParentId = null, Priority = "High" });
        TreeData.Add(new BusinessObject() { TaskId = 8, TaskName = "Child Task 7", Duration = 3, Progress = 38, ParentId = 7, Priority = "Critical" });
        TreeData.Add(new BusinessObject() { TaskId = 9, TaskName = "Child Task 8", Duration = 7, Progress = 70, ParentId = 7, Priority = "Low" });
    }
}
Blazor TreeGrid

NOTE

View Sample in GitHub.

Handling exceptions

Exception handling in Tree Grid identifies exceptions and notifies them through the OnActionFailure event. When configuring the Tree Grid or enabling specific features through its API, mistakes can occur. The OnActionFailure event can be used to manage these exceptions. This event triggers when such mistakes happen. The OnActionFailure event handles various scenarios, including:

  • For CRUD operations, row drag and drop, and persisiting the selection, ensure the IsPrimaryKey property is mapped to a unique data column. Failure to do so will cause an exception.
  • Paging is not supported with Virtualization. Enabling Paging with Virtualization will result in an exception.
  • To render the Tree Grid, map either the DataSource or Columns property. Failure to do so will result in an exception.
  • Freeze columns by mapping either IsFrozen or FrozenColumns. Enabling both properties simultaneously will result in an exception.

  • The DetailTemplate is not supported with Virtualization and Stacked Header. Enabling them with these features will result in an exception.

  • The FrozenRows and FrozenColumns are not supported with RowTemplate, DetailTemplate, and Cell Editing. Enabling them with these features will result in an exception.

  • In Stacked Header, the Freeze direction is incompatible with Column Reordering.
  • Selection functionality is not supported when using RowTemplate. Enabling both properties simultaneously will result in an exception.
  • Set the TreeColumnIndex value to display the tree structure. Make sure the value does not exceed the total column count, or it will result in an exception.
  • For Virtualization, do not specify height and width in percentages. Using percentages will result in an error.
  • When using the default filter (FilterBar) type, do not apply the other FilterType to columns within the same tree grid, as this will result in an exception.
  • In Tree Grid, avoid enabling IdMapping and ChildMapping simultaneously. Enabling both properties at the same time will result in an exception.
  • The ShowCheckbox column should only be defined in the tree column. Defining it elsewhere will result in an exception.
  • The TextAlign right is not applicable for tree columns in the Tree Grid. Enabling right alignment for tree columns will result in an exception.

The following code example shows how to use the OnActionFailure event in the Tree Grid control to display an exception when IsPrimaryKeyare not configured properly in the Tree Grid.

@using Syncfusion.Blazor.TreeGrid;
@using Syncfusion.Blazor.Data;

 <span class="error">@ErrorDetails</span>
<SfTreeGrid DataSource="@TreeData" IdMapping="TaskId" ParentIdMapping="ParentId" TreeColumnIndex="1">
    <TreeGridEditSettings AllowEditing></TreeGridEditSettings>
    <TreeGridEvents TValue="BusinessObject" OnActionFailure="ActionFailure"></TreeGridEvents>
    <TreeGridColumns>
        <TreeGridColumn Field="TaskId" HeaderText="Task ID" Width="80" TextAlign="Syncfusion.Blazor.Grids.TextAlign.Right"></TreeGridColumn>
        <TreeGridColumn Field="TaskName" HeaderText="Task Name" Width="160"></TreeGridColumn>
        <TreeGridColumn Field="StartDate" HeaderText="Start Date" Format="d" Type="Syncfusion.Blazor.Grids.ColumnType.DateOnly" Width="152" TextAlign="Syncfusion.Blazor.Grids.TextAlign.Right"></TreeGridColumn>
        <TreeGridColumn Field="StartTime" HeaderText="Start Time" Type="Syncfusion.Blazor.Grids.ColumnType.TimeOnly" Width="100" TextAlign="Syncfusion.Blazor.Grids.TextAlign.Right"></TreeGridColumn>
        <TreeGridColumn Field="Duration" HeaderText="Duration" Width="100" TextAlign="Syncfusion.Blazor.Grids.TextAlign.Right"></TreeGridColumn>
        <TreeGridColumn Field="Progress" HeaderText="Progress" Width="100" TextAlign="Syncfusion.Blazor.Grids.TextAlign.Right"></TreeGridColumn>
    </TreeGridColumns>
</SfTreeGrid>
<style>
    .error {
        color: red;
    }
</style>

@code{

    private string ErrorDetails = "";
    public class BusinessObject
    {
        public int TaskId { get; set; }
        public string TaskName { get; set; }
        public DateOnly? StartDate { get; set; }
        public TimeOnly? StartTime { get; set; }
        public int Duration { get; set; }
        public int Progress { get; set; }
        public string Priority { get; set; }
        public int? ParentId { get; set; }
    }

    public void ActionFailure(Syncfusion.Blazor.Grids.FailureEventArgs args)
    {
        this.ErrorDetails = args.Error.Message.ToString();
        StateHasChanged();
    }

    public List<BusinessObject> TreeData = new List<BusinessObject>();

    protected override void OnInitialized()
    {
        TreeData.Add(new BusinessObject() { TaskId = 1, TaskName = "Parent Task 1", StartDate = new DateOnly(2021, 03, 02), StartTime = new TimeOnly(10, 00, 00), Duration = 10, Progress = 70, ParentId = null, Priority = "High" });
        TreeData.Add(new BusinessObject() { TaskId = 2, TaskName = "Child task 1", StartDate = new DateOnly(2021, 03, 04), StartTime = new TimeOnly(11, 30, 00), Duration = 4, Progress = 80, ParentId = 1, Priority = "Normal" });
        TreeData.Add(new BusinessObject() { TaskId = 3, TaskName = "Child Task 2", StartDate = new DateOnly(2021, 03, 06), StartTime = new TimeOnly(12, 00, 00), Duration = 5, Progress = 65, ParentId = 1, Priority = "Critical" });
        TreeData.Add(new BusinessObject() { TaskId = 4, TaskName = "Parent Task 2", StartDate = new DateOnly(2021, 03, 08), StartTime = new TimeOnly(13, 30, 00), Duration = 6, Progress = 77, ParentId = null, Priority = "Low" });
        TreeData.Add(new BusinessObject() { TaskId = 5, TaskName = "Child Task 5", StartDate = new DateOnly(2021, 07, 10), StartTime = new TimeOnly(14, 00, 00), Duration = 9, Progress = 25, ParentId = 4, Priority = "Normal" });
        TreeData.Add(new BusinessObject() { TaskId = 6, TaskName = "Child Task 6", StartDate = new DateOnly(2021, 10, 12), StartTime = new TimeOnly(16, 00, 00), Duration = 9, Progress = 7, ParentId = 5, Priority = "Normal" });
        TreeData.Add(new BusinessObject() { TaskId = 7, TaskName = "Parent Task 3", StartDate = new DateOnly(2021, 10, 14), StartTime = new TimeOnly(17, 30, 00), Duration = 4, Progress = 45, ParentId = null, Priority = "High" });
        TreeData.Add(new BusinessObject() { TaskId = 8, TaskName = "Child Task 7", StartDate = new DateOnly(2021, 10, 16), StartTime = new TimeOnly(18, 00, 00), Duration = 3, Progress = 38, ParentId = 7, Priority = "Critical" });
        TreeData.Add(new BusinessObject() { TaskId = 9, TaskName = "Child Task 8", StartDate = new DateOnly(2021, 02, 18), StartTime = new TimeOnly(19, 30, 00), Duration = 7, Progress = 70, ParentId = 7, Priority = "Low" });
    }
}

See also