// ✅ REQUIRED - Must match data property name exactly
<TreeGridComponent 
  dataSource={data}
  childMapping='subtasks'>
  <ColumnsDirective>
    {/* Columns */}
  </ColumnsDirective>
</TreeGridComponent>

// ❌ WRONG - Will not work
<TreeGridComponent 
  dataSource={data}>
  {/* No childMapping = No expansion possible */}
</TreeGridComponent>

// ✅ CORRECT - childMapping matches 'subtasks' property
const data = [
  {
    TaskID: 1,
    TaskName: 'Parent',
    subtasks: [  // Must match childMapping value exactly
      { TaskID: 2, TaskName: 'Child' }
    ]
  }
];

// Alternative: Flat structure with parent IDs
<TreeGridComponent 
  dataSource={flatData}
  idMapping='TaskID'
  parentIdMapping='ParentID'
  hasChildMapping='isParent'>
</TreeGridComponent>

// ✅ CORRECT - Type matches column definition
const data = [
  {
    TaskID: 1,              // number type
    TaskName: 'Planning',   // string type
    StartDate: new Date(),  // Date object for date columns
  }
];

// Column definition must match data types
<ColumnsDirective>
  <ColumnDirective field='TaskID' headerText='ID' type='number'></ColumnDirective>
  <ColumnDirective field='TaskName' headerText='Task' type='string'></ColumnDirective>
  <ColumnDirective field='StartDate' headerText='Date' type='date' format='yMd'></ColumnDirective>
</ColumnsDirective>

// ❌ WRONG - Type mismatch
const data = [
  {
    TaskID: '1',            // String instead of number
    StartDate: '02/03/2024' // String instead of Date object
  }
];

import React from 'react';
import { TreeGridComponent, ColumnsDirective, ColumnDirective, Inject, Page } from '@syncfusion/ej2-react-treegrid';
import { DataManager, UrlAdaptor } from '@syncfusion/ej2-data';

interface ITreeData {
  TaskID?: number;
  TaskName?: string;
  parentID: number | null;
  Children?: ITreeData[];
}

export default function App() {
  const data: ITreeData[] = [
    {
      TaskID: 1,
      TaskName: 'Planning',
      parentID: null,
      Children: [{ TaskID: 2, TaskName: 'Plan timeline', parentID: 1 }]
    }
  ];

  return (
    <TreeGridComponent
      dataSource={data}
      childMapping="Children"
      treeColumnIndex={1}
      height="auto"
      allowPaging={true}
    >
      <ColumnsDirective>
        <ColumnDirective field="TaskID" headerText="Task ID" width={80} />
        <ColumnDirective field="TaskName" headerText="Task Name" width={160} />
      </ColumnsDirective>
      <Inject services={[Page]} />
    </TreeGridComponent>
  );
}