Syncfusion ASP.NET Core TreeGrid

The TreeGrid component visualizes self-referential hierarchical data in a tabular format. It supports child/parent data binding (via childMapping or idMapping), expand/collapse of child rows, sorting, filtering, editing, paging, export, and virtualization.

⚠️ Security & Trust Boundary

• The TreeGrid skill does not perform any remote data access.
• All external API interaction is handled by a separate DataManager skill outside this skill’s trust boundary.

When to Use This Skill

• Rendering hierarchical or parent-child structured data in ASP.NET Core (e.g. project tasks, org charts, bill of materials)
• Implementing CRUD operations on tree-structured data
• Sorting, filtering, or searching across hierarchical records
• Exporting tree data to Excel or PDF
• Handling large datasets with virtual scrolling or infinite scroll

Refer to Properties & Configuration, Events & Lifecycle, and Classes & Enums Reference files for complete API lookup.

Table of Contents

• Data Structure Rules
• Documentation and Navigation Guide
• Quick Start Example
• Common Patterns

Data Structure Rules

Rule 1: childMapping is MANDATORY for Hierarchical Data

Severity: 🔴 CRITICAL - Grid will not expand/collapse without this

Requirement:

CSHTML View:

<!-- ✅ REQUIRED - childMapping matches data property name exactly -->
<ejs-treegrid id="TreeGrid" dataSource="@ViewBag.data" childMapping="Children"
              treeColumnIndex="1" allowPaging="true">
    <e-treegrid-columns>
        <e-treegrid-column field="TaskId" headerText="Task ID" 
                           isPrimaryKey="true" textAlign="Right" width="95"></e-treegrid-column>
        <e-treegrid-column field="TaskName" headerText="Task Name" width="220"></e-treegrid-column>
        <e-treegrid-column field="Duration" headerText="Duration" textAlign="Right" width="100"></e-treegrid-column>
    </e-treegrid-columns>
</ejs-treegrid>

<!-- ❌ WRONG - No childMapping = No expansion possible -->
<ejs-treegrid id="TreeGrid2" dataSource="@ViewBag.data">
    <!-- Missing childMapping & treeColumnIndex - Won't expand! -->
</ejs-treegrid>

Data Format C# Model:

public class TreeGridItem
{
    public int TaskId { get; set; }
    public string TaskName { get; set; }
    public int Duration { get; set; }
    public List<TreeGridItem> Children { get; set; }  // Must match childMapping="Children"
}

// Sample data
var data = new List<TreeGridItem>
{
    new TreeGridItem
    {
        TaskId = 1,
        TaskName = "Planning",
        Duration = 5,
        Children = new List<TreeGridItem>  // ✅ CORRECT - nested Children property
        {
            new TreeGridItem { TaskId = 2, TaskName = "Identify Site", Duration = 2 },
            new TreeGridItem { TaskId = 3, TaskName = "Perform Test",   Duration = 3 }
        }
    }
};

Alternative: Flat Structure with Parent IDs:

<!-- Use idMapping + parentIdMapping instead of childMapping -->
<ejs-treegrid id="TreeGrid" dataSource="@ViewBag.flatData" 
              idMapping="TaskId" parentIdMapping="ParentId" treeColumnIndex="1">
    ...
</ejs-treegrid>

var flatData = new List<TreeGridItem>
{
    new TreeGridItem { TaskId = 1, TaskName = "Planning", ParentId = null },
    new TreeGridItem { TaskId = 2, TaskName = "Identify Site", ParentId = 1 },
    new TreeGridItem { TaskId = 3, TaskName = "Perform Test",   ParentId = 1 }
};

Rule 2: Data Type Matching is MANDATORY

Severity: 🟠 IMPORTANT - Type mismatches cause rendering/sorting issues

C# Model - Correct Types:

public class TreeGridItem
{
    public int TaskId { get; set; }              // ✅ int type
    public string TaskName { get; set; }         // ✅ string type
    public DateTime StartDate { get; set; }      // ✅ DateTime for date columns
    public decimal Price { get; set; }           // ✅ decimal for currency
}

var data = new List<TreeGridItem>
{
    new TreeGridItem
    {
        TaskId = 1,                              // int, not string "1"
        TaskName = "Planning",
        StartDate = new DateTime(2024, 3, 15),   // DateTime, not "03/15/2024"
        Price = 1500.50m                         // decimal, not string "1500.50"
    }
};

CSHTML Column Definition - Match Data Types:

<ejs-treegrid id="TreeGrid" dataSource="@ViewBag.data" childMapping="Children">
    <e-treegrid-columns>
        <!-- field "TaskId" is int, so type="number" -->
        <e-treegrid-column field="TaskId" headerText="Task ID" 
                           type="number" textAlign="Right" width="95"></e-treegrid-column>
        <!-- field "TaskName" is string, type="string" (default) -->
        <e-treegrid-column field="TaskName" headerText="Task Name" width="220"></e-treegrid-column>
        <!-- field "StartDate" is DateTime, so type="date" with format -->
        <e-treegrid-column field="StartDate" headerText="Start Date" 
                           type="date" format="yMd" textAlign="Right" width="115"></e-treegrid-column>
        <!-- field "Price" is decimal, type="number" with currency format -->
        <e-treegrid-column field="Price" headerText="Price" 
                           type="number" format="c2" textAlign="Right" width="100"></e-treegrid-column>
    </e-treegrid-columns>
</ejs-treegrid>

❌ WRONG - Type Mismatch Issues:

// Bad model - mixing string where types should be specific
var badData = new List<TreeGridItem>
{
    new TreeGridItem
    {
        TaskId = "1",                // ❌ String instead of int
        StartDate = "02/03/2024"     // ❌ String instead of DateTime
    }
};
// Result: Sorting fails, formatting doesn't work, expand/collapse issues

Documentation and Navigation Guide

Getting Started

📄 Read: references/getting-started.md

• NuGet installation (Syncfusion.EJ2.AspNet.Core)
• TagHelper registration in _ViewImports.cshtml
• CSS/script CDN setup in _Layout.cshtml
• Basic <ejs-treegrid> declaration
• Binding local data with childMapping / treeColumnIndex
• Defining columns with <e-treegrid-columns>
• Enabling paging, sorting, and filtering at startup
• Error handling with actionFailure

Data Binding

📄 Read: references/data-binding.md

• Local data with childMapping (nested list) and idMapping/parentIdMapping (flat list)
• Remote data via DataManager with OData/WebAPI adaptor
• Ajax/Fetch-based binding
• expandStateMapping — control initial expand/collapse state per row
• Handling null or missing parent references

Columns

📄 Read: references/columns.md

• Column field, headerText, textAlign, width, type, format
• treeColumnIndex — which column shows expand/collapse arrows
• Number/date formatting (N2, C2, yMd, custom)
• Lock columns, show/hide columns dynamically
• Checkbox column (showCheckbox, autoCheckHierarchy)
• valueAccessor for computed/expression columns
• Column menu (showColumnMenu)
• Column reorder, resize, auto-fit
• Column templates, column spanning, headers, complex data binding

Sorting

📄 Read: references/sorting.md

• Enable with allowSorting
• Initial sort via e-treegrid-sortsettings
• Multi-column sort (CTRL + click)
• Disable sort per column (allowSorting: false on column)
• Sort events (actionBegin, actionComplete)
• Programmatic sort/clear via sortColumn / clearSorting

Filtering

📄 Read: references/filtering.md

• Enable with allowFiltering
• Filter types: FilterBar (default), Menu, Excel-like
• Filter hierarchy modes: Parent, Child, Both, None
• Initial filter with predicate
• Filter operators (startswith, contains, equal, greaterthan, etc.)
• Disable filter per column

Editing

📄 Read: references/editing.md

• Enable with e-treegrid-editSettings and isPrimaryKey
• Edit modes: Cell, Row, Dialog, Batch
• Toolbar with Add/Edit/Delete/Update/Cancel
• newRowPosition: Top, Bottom, Above, Below, Child
• Delete confirmation dialog
• Default column values on add
• Disable editing per column
• Validation rules
• Persisting edited data to server

Paging

📄 Read: references/paging.md

• Enable with allowPaging
• e-treegrid-pagesettings: pageSize, pageSizeMode (All/Root)
• Page size dropdown, pager template
• Render pager at top via dataBound event

Selection

📄 Read: references/selection.md

• Row, Cell, Both selection modes
• Single vs Multiple type (e-treegrid-selectionsettings)
• Checkbox selection with checkboxMode
• Programmatic selection

Aggregates

📄 Read: references/aggregates.md

• Built-in types: Sum, Average, Min, Max, Count, Truecount, Falsecount
• Footer aggregate and child (parent row footer) aggregate
• showChildSummary to show child aggregate
• Custom aggregate function
• footerTemplate for custom display

Row Customization

📄 Read: references/row.md

• rowDataBound for conditional styling
• Alternate row styling (.e-altrow)
• Row template, detail template
• Row drag-and-drop (allowRowDragAndDrop)
• Row height, row spanning

Cell Customization

📄 Read: references/cell.md

• queryCellInfo for per-cell customization
• Custom attributes on cells
• Auto text wrap (allowTextWrap)
• Clip mode (Clip, Ellipsis, EllipsisWithTooltip)
• Grid lines

Export (Excel)

📄 Read: references/excel-export.md

• Excel export (allowExcelExport, excelExport())
• Persist collapsed state in export
• Custom aggregates in export
• Headers/footers, cell style customization
• Server-side export options

PDF Export

📄 Read: references/pdf-export.md

• PDF export (allowPdfExport, pdfExport())
• PDF export options and configurations
• Page orientation (Portrait, Landscape)
• Custom headers, footers, and styling
• Cell style customization for PDF
• Server-side PDF export

Print

📄 Read: references/print.md

• Enable printing with allowPrinting
• Print via toolbar button or external button
• Print current page only (printMode: 'CurrentPage')
• Show/hide columns during print
• Handling large datasets
• Page setup configuration

Clipboard

📄 Read: references/clipboard.md

• Copy to clipboard with Ctrl+C and Ctrl+Shift+H
• Copy with external buttons
• Copy hierarchy modes (Parent, Child, Both, None)
• AutoFill feature with drag-to-fill
• Paste functionality with Ctrl+V
• Type conversion limitations

Scrolling

📄 Read: references/scrolling.md

• Basic scrolling and responsive configurations
• Sticky header, row/column virtualization, and infinite scrolling
• Performance optimization for large datasets

Adaptive Layout

📄 Read: references/adaptive.md

• Responsive UI with enableAdaptiveUI for mobile and tablet devices
• Adaptive dialog mode for filtering and editing on small screens
• Expand/collapse behavior optimization for touch interaction
• Column chooser adaptation to mobile dialogs
• Vertical row rendering mode for enhanced mobile readability
• Best practices for responsive TreeGrid design

Frozen Rows and Columns

📄 Read: references/frozen.md

• Freeze rows and columns using frozenRows, frozenColumns, or isFrozen property
• Freeze direction control with Left/Right positioning
• Limitations and compatibility considerations with other features

Styling and Appearance

📄 Read: references/styling-and-appearance.md

• Customize Tree Grid styling with CSS classes for all elements
• CSS override examples for headers, rows, cells, selection, and summary
• Custom theme options using Syncfusion Theme Studio

Immutable Mode

📄 Read: references/immutable.md

• Enable with enableImmutableMode="true"
• Performance optimization for large datasets
• Primary key requirement for comparison
• Selective re-render of modified rows
• Performance benefits for batch operations
• Limitations and workarounds

Toolbar

📄 Read: references/toolbar.md

• Built-in toolbar items (Add, Edit, Delete, Update, Cancel, Search, ExcelExport, PdfExport, etc.)
• Custom toolbar items with text, icons, tooltips, and alignment
• Toolbar click handler with event arguments
• Built-in item ID patterns and identification
• Disabling toolbar items dynamically based on row selection
• Best practices for toolbar design and layout
• Edit mode integration with toolbar buttons

Context Menu

📄 Read: references/context-menu.md

• Default context menu items for data manipulation and column operations
• Custom context menu items with hierarchy-aware functionality
• Contextual visibility using target selectors (.e-content, .e-headercell)
• Context menu click handler with row and column information
• Enable/disable items dynamically based on row state (parent/child)
• Hierarchy-aware expand/collapse menus for TreeGrid
• Advanced scenarios: parent-only operations, conditional menu items
• Best practices for TreeGrid-specific context menu design

Searching

📄 Read: references/searching.md

• Enable full-text search across TreeGrid hierarchical data
• Add search toolbar item for real-time filtering as user types
• Configure search field scope (all columns or specific column subset)
• Search with operators (contains, startsWith, endsWith, equal, notEqual)
• Programmatic search triggering from external input controls
• Search in hierarchy with automatic parent row expansion on child matches
• Clear search and reset to show all rows
• Handle search events (actionBegin, actionComplete) for custom logic
• Best practices for searching large hierarchical datasets

Loading Animation

📄 Read: references/loading-animation.md

• Loading indicator types: Spinner (default) and Shimmer animations
• When loading animation displays (initial render, sorting, filtering, paging, searching)
• Remote data binding with loading animation via DataManager
• Programmatic control of loading indicator (show/hide)
• Customizing loading behavior with action events
• Best practices for UX with loading states
• Mobile and slow network optimization

Globalization & Localization

📄 Read: references/global-local.md

• Culture-specific number and date formatting via locale property
• Localization of UI strings (toolbar, dialogs, pager, filter, expand/collapse text)
• Right-to-left (RTL) layout support for Arabic, Hebrew, and other RTL languages
• CLDR data loading and culture configuration
• Format codes (C2, yMd, N2) for currency, date, and number columns
• Multi-locale support with dynamic language switching
• Best practices for global applications

State Management

📄 Read: references/state-management.md

• Persist TreeGrid state across sessions with enablePersistence
• Save and restore sorting, filtering, paging, and column preferences
• Preserve expand/collapse state of parent rows on page reload
• LocalStorage-based automatic persistence and manual state retrieval
• Reset TreeGrid state to defaults programmatically
• Custom server-side state persistence for sensitive data
• Best practices for state management in hierarchical data

Accessibility

📄 Read: references/accessibility.md

• WCAG 2.1 compliance
• Keyboard navigation
• ARIA attributes
• Screen reader support

Properties & Configuration

📄 Read: references/properties-configuration.md

• Lookup 145+ TreeGrid properties organized by concern
• Data configuration (dataSource, childMapping, idMapping, parentIdMapping, expandStateMapping)
• UI layout (height, width, rowHeight, treeColumnIndex)
• Grid appearance (gridLines, enableAltRow, enableRtl, enableHover, clipMode)
• Feature toggles table (Paging, Sorting, Filtering, Editing, Selection, etc.)
• Performance tuning (virtualization, infinite scroll, immutable mode, persistence)
• Event callbacks and handlers
• Advanced configuration objects (EditSettings, PageSettings, FilterSettings, SelectionSettings, etc.)

Events & Lifecycle

📄 Read: references/events-methods.md

• Lifecycle events (created, load, dataBound, beforeDataBound, dataSourceChanged)
• Action events (actionBegin, actionComplete, actionFailure)
• Expand/collapse events (expanding, expanded, collapsing, collapsed)
• Edit events (beginEdit, cellEdit, cellSave, cellSaved, batchAdd, batchDelete, beforeBatchSave)
• Selection events (rowSelected, rowSelecting, rowDeselected, checkboxChange)
• Drag & drop events (rowDragStart, rowDrop, columnDragStart, columnDrop)
• Custom rendering events (queryCellInfo, rowDataBound, detailDataBound)
• Export events (beforeExcelExport, excelExportComplete, beforePdfExport, pdfQueryCellInfo)
• Complete event signatures and examples for each category

Settings Classes & Enums Reference

📄 Read: references/classes-enums-reference.md

• Enums: CopyHierarchyType, EditMode, FilterHierarchyMode, FilterType, PageSizeMode, RowPosition, WrapMode
• Settings classes: EditSettings, PageSettings, SortSettings, FilterSettings, SelectionSettings, RowDropSettings, InfiniteScrollSettings
• Column configuration: TreeGridColumn, StackedHeaderCell classes
• Builder pattern for fluent API and tag helper approach
• Complete property definitions for each settings class

Quick Start Example

Minimal TreeGrid with local data, columns, sorting, filtering, and paging:

_ViewImports.cshtml

@addTagHelper *, Syncfusion.EJ2

_Layout.cshtml (inside <head>)

<!-- Syncfusion ASP.NET Core controls styles -->
<link rel="stylesheet" href="~/ej2/ej2version/fluent2.css" />
<!-- Syncfusion ASP.NET Core controls scripts -->
<script src="~/ej2/ej2version/dist/ej2.min.js"></script>

_Layout.cshtml (end of <body>)

<ejs-scripts></ejs-scripts>

Index.cshtml

@{
    var data = TreeGridItems.GetTreeData();
}

<ejs-treegrid id="TreeGrid" dataSource="@data" childMapping="Children"
              treeColumnIndex="1" allowSorting="true" allowFiltering="true" allowPaging="true">
    <e-treegrid-pagesettings pageSize="5"></e-treegrid-pagesettings>
    <e-treegrid-columns>
        <e-treegrid-column field="TaskId" headerText="Task ID" isPrimaryKey="true"
                           textAlign="Right" width="95"></e-treegrid-column>
        <e-treegrid-column field="TaskName" headerText="Task Name" width="220"></e-treegrid-column>
        <e-treegrid-column field="StartDate" headerText="Start Date"
                           textAlign="Right" format="yMd" type="date" width="115"></e-treegrid-column>
        <e-treegrid-column field="Duration" headerText="Duration"
                           textAlign="Right" width="100"></e-treegrid-column>
    </e-treegrid-columns>
</ejs-treegrid>

Index.cshtml.cs (or Controller)

public class TreeGridItems
{
    public int TaskId { get; set; }
    public string TaskName { get; set; }
    public DateTime StartDate { get; set; }
    public int Duration { get; set; }
    public List<TreeGridItems> Children { get; set; }

    public static List<TreeGridItems> GetTreeData()
    {
        return new List<TreeGridItems>
        {
            new TreeGridItems
            {
                TaskId = 1, TaskName = "Planning",
                StartDate = new DateTime(2021, 6, 7), Duration = 5,
                Children = new List<TreeGridItems>
                {
                    new TreeGridItems { TaskId = 2, TaskName = "Plan timeline", StartDate = new DateTime(2021, 6, 7), Duration = 5 },
                    new TreeGridItems { TaskId = 3, TaskName = "Plan budget",   StartDate = new DateTime(2021, 6, 7), Duration = 5 }
                }
            }
        };
    }
}

Common Patterns

When to use childMapping vs idMapping

• childMapping: Data is nested (each parent has a Children list) → bind childMapping="Children"
• idMapping + parentIdMapping: Data is flat with parent ID references → bind idMapping="TaskId" parentIdMapping="ParentId"

Enable Editing with Toolbar

<ejs-treegrid id="TreeGrid" dataSource="@data" childMapping="Children"
              treeColumnIndex="1" toolbar="@(new List<string>() {"Add","Edit","Delete","Update","Cancel"})">
    <e-treegrid-editsettings allowAdding="true" allowEditing="true"
                             allowDeleting="true" mode="Row"></e-treegrid-editsettings>
    <e-treegrid-columns>
        <e-treegrid-column field="TaskId" headerText="Task ID"
                           isPrimaryKey="true" width="90"></e-treegrid-column>
        <e-treegrid-column field="TaskName" headerText="Task Name" width="220"></e-treegrid-column>
    </e-treegrid-columns>
</ejs-treegrid>

Always set isPrimaryKey="true" on one column — editing and delete operations require it.

Key Error Avoidance

• Do NOT enable paging and virtualization simultaneously
• Do NOT set isFrozen and frozenColumns at the same time
• showCheckbox column must be defined only on the tree column
• textAlign="Right" is not applicable for the tree column
• Do NOT enable idMapping and childMapping simultaneously