---
title: "Tree Data - Expanding Groups"
enterprise: true
framework: angular
version: "36.1.0"
---

# Tree Data - Expanding Groups

Configure the initial expanded group row state when using Tree Data.

## Expanding by Group Level

When providing a hierarchy, all levels will default to a collapsed state. This can be configured by setting the `groupDefaultExpanded` grid option. Providing a number will expand all groups down to that level, or providing -1 will expand all groups.

#### Group Default Expanded

```ts
import { Component } from "@angular/core";
import { AgGridAngular } from "ag-grid-angular";
import {
  AutoGroupColumnDef,
  ClientSideRowModelModule,
  ColDef,
  ColGroupDef,
  GetDataPath,
  GridApi,
  GridOptions,
  GridReadyEvent,
  ModuleRegistry,
  TextFilterModule,
  enableDevValidations,
} from "ag-grid-community";
import { TreeDataModule } from "ag-grid-enterprise";
import { getData } from "./data";
if (process.env.NODE_ENV !== "production") {
  enableDevValidations();
}

ModuleRegistry.registerModules([
  ClientSideRowModelModule,
  TreeDataModule,
  TextFilterModule,
]);

@Component({
  selector: "my-app",
  standalone: true,
  imports: [AgGridAngular],
  template: `<ag-grid-angular
    style="width: 100%; height: 100%;"
    [columnDefs]="columnDefs"
    [defaultColDef]="defaultColDef"
    [autoGroupColumnDef]="autoGroupColumnDef"
    [groupDefaultExpanded]="groupDefaultExpanded"
    [treeData]="true"
    [getDataPath]="getDataPath"
    [rowData]="rowData"
  /> `,
})
export class AppComponent {
  columnDefs: ColDef[] = [
    { field: "created" },
    { field: "modified" },
    {
      field: "size",
      aggFunc: "sum",
      valueFormatter: (params) => {
        const sizeInKb = params.value / 1024;
        if (sizeInKb > 1024) {
          return `${+(sizeInKb / 1024).toFixed(2)} MB`;
        } else {
          return `${+sizeInKb.toFixed(2)} KB`;
        }
      },
    },
  ];
  defaultColDef: ColDef = {
    flex: 1,
    minWidth: 100,
  };
  autoGroupColumnDef: AutoGroupColumnDef = {
    headerName: "File Explorer",
    minWidth: 280,
    filter: "agTextColumnFilter",
    cellRendererParams: {
      suppressCount: true,
    },
  };
  groupDefaultExpanded = 1;
  getDataPath: GetDataPath = (data) => data.path;
  rowData: any[] | null = getData();
}
```

[Live example: Group Default Expanded](https://www.ag-grid.com/examples/tree-data-opening-groups/group-default-expanded/angular/)

The example above uses the following configuration to expand the first level of groups, but no others:

```ts
<ag-grid-angular
    [groupDefaultExpanded]="groupDefaultExpanded"
    /* other grid options ... */ />

this.groupDefaultExpanded = 1;
```

## Expanding via Callback

To granularly determine which groups should be expanded by default, use the `isGroupOpenByDefault` grid callback.

| Property | Type | Required | Default | Description |
| --- | --- | --- | --- | --- |
| `isGroupOpenByDefault` | `IsGroupOpenByDefault` |  |  | (Client-side Row Model only) Allows group rows to be open by default. For master rows use `isMasterOpenByDefault`. Modules (any of): [`RowGroupingModule`](https://www.ag-grid.com/angular-data-grid/modules/), [`TreeDataModule`](https://www.ag-grid.com/angular-data-grid/modules/). |

#### Open by Default

```ts
import { Component } from "@angular/core";
import { AgGridAngular } from "ag-grid-angular";
import {
  AutoGroupColumnDef,
  ClientSideRowModelModule,
  ColDef,
  ColGroupDef,
  GetDataPath,
  GridApi,
  GridOptions,
  GridReadyEvent,
  IsGroupOpenByDefault,
  IsGroupOpenByDefaultParams,
  ModuleRegistry,
  TextFilterModule,
  enableDevValidations,
} from "ag-grid-community";
import { TreeDataModule } from "ag-grid-enterprise";
import { getData } from "./data";
if (process.env.NODE_ENV !== "production") {
  enableDevValidations();
}

ModuleRegistry.registerModules([
  ClientSideRowModelModule,
  TreeDataModule,
  TextFilterModule,
]);

@Component({
  selector: "my-app",
  standalone: true,
  imports: [AgGridAngular],
  template: `<ag-grid-angular
    style="width: 100%; height: 100%;"
    [columnDefs]="columnDefs"
    [defaultColDef]="defaultColDef"
    [autoGroupColumnDef]="autoGroupColumnDef"
    [isGroupOpenByDefault]="isGroupOpenByDefault"
    [treeData]="true"
    [getDataPath]="getDataPath"
    [rowData]="rowData"
  /> `,
})
export class AppComponent {
  columnDefs: ColDef[] = [
    { field: "created" },
    { field: "modified" },
    {
      field: "size",
      aggFunc: "sum",
      valueFormatter: (params) => {
        const sizeInKb = params.value / 1024;
        if (sizeInKb > 1024) {
          return `${+(sizeInKb / 1024).toFixed(2)} MB`;
        } else {
          return `${+sizeInKb.toFixed(2)} KB`;
        }
      },
    },
  ];
  defaultColDef: ColDef = {
    flex: 1,
    minWidth: 100,
    filter: true,
  };
  autoGroupColumnDef: AutoGroupColumnDef = {
    headerName: "File Explorer",
    minWidth: 280,
    filter: "agTextColumnFilter",
    cellRendererParams: {
      suppressCount: true,
    },
  };
  isGroupOpenByDefault: IsGroupOpenByDefault = (
    params: IsGroupOpenByDefaultParams,
  ) => {
    return (
      (params.level === 0 && params.key === "Documents") ||
      (params.level === 1 && params.key === "Work") ||
      (params.level === 2 && params.key === "ProjectBeta")
    );
  };
  getDataPath: GetDataPath = (data) => data.path;
  rowData: any[] | null = getData();
}
```

[Live example: Open by Default](https://www.ag-grid.com/examples/tree-data-opening-groups/open-by-default/angular/)

The example above uses the following configuration to expand the `ProjectBeta` groups by default:

```ts
<ag-grid-angular
    [isGroupOpenByDefault]="isGroupOpenByDefault"
    /* other grid options ... */ />

this.isGroupOpenByDefault = (params) => {
    return (
        (params.level === 0 && params.key === 'Documents') ||
        (params.level === 1 && params.key === 'Work') ||
        (params.level === 2 && params.key === 'ProjectBeta')
    );
};
```

> **Note**
>
> Row keys are not always unique, so it is recommended to instead use the node ID or data path to identify the row.

## Scrolling Child Rows into View

When expanding a group the vertical scroll does not change, which can result in the child rows not being visible. You can use the `ensureIndexVisible()` function on the API to ensure the index is visible, scrolling the table if needed.

In the example below, if you expand a group at the bottom, the grid will scroll so that all of the children of the group are visible.

#### Row Group Scroll

```ts
import { Component } from "@angular/core";
import { AgGridAngular } from "ag-grid-angular";
import {
  AutoGroupColumnDef,
  ClientSideRowModelModule,
  ColDef,
  ColGroupDef,
  GetDataPath,
  GridApi,
  GridOptions,
  GridReadyEvent,
  ModuleRegistry,
  RowGroupOpenedEvent,
  ScrollApiModule,
  TextFilterModule,
  enableDevValidations,
} from "ag-grid-community";
import { TreeDataModule } from "ag-grid-enterprise";
import { getData } from "./data";
if (process.env.NODE_ENV !== "production") {
  enableDevValidations();
}

ModuleRegistry.registerModules([
  ScrollApiModule,
  ClientSideRowModelModule,
  TreeDataModule,
  TextFilterModule,
]);

@Component({
  selector: "my-app",
  standalone: true,
  imports: [AgGridAngular],
  template: `<ag-grid-angular
    style="width: 100%; height: 100%;"
    [columnDefs]="columnDefs"
    [defaultColDef]="defaultColDef"
    [autoGroupColumnDef]="autoGroupColumnDef"
    [rowData]="rowData"
    [treeData]="true"
    [getDataPath]="getDataPath"
    [animateRows]="false"
    (rowGroupOpened)="onRowGroupOpened($event)"
    (gridReady)="onGridReady($event)"
  /> `,
})
export class AppComponent {
  private gridApi!: GridApi;

  columnDefs: ColDef[] = [
    { field: "created" },
    { field: "modified" },
    {
      field: "size",
      aggFunc: "sum",
      valueFormatter: (params) => {
        const sizeInKb = params.value / 1024;
        if (sizeInKb > 1024) {
          return `${+(sizeInKb / 1024).toFixed(2)} MB`;
        } else {
          return `${+sizeInKb.toFixed(2)} KB`;
        }
      },
    },
  ];
  defaultColDef: ColDef = {
    flex: 1,
    minWidth: 100,
    filter: true,
  };
  autoGroupColumnDef: AutoGroupColumnDef = {
    headerName: "File Explorer",
    minWidth: 280,
    filter: "agTextColumnFilter",
    cellRendererParams: {
      suppressCount: true,
    },
  };
  rowData: any[] | null = getData();
  getDataPath: GetDataPath = (data) => data.path;

  onRowGroupOpened(event: RowGroupOpenedEvent<IOlympicData>) {
    if (event.expanded) {
      const rowNodeIndex = event.node.rowIndex!;
      // factor in child nodes so we can scroll to correct position
      const childCount = event.node.childrenAfterSort
        ? event.node.childrenAfterSort.length
        : 0;
      const newIndex = rowNodeIndex + childCount;
      this.gridApi.ensureIndexVisible(newIndex);
    }
  }

  onGridReady(params: GridReadyEvent) {
    this.gridApi = params.api;
  }
}
```

[Live example: Row Group Scroll](https://www.ag-grid.com/examples/tree-data-opening-groups/row-group-scroll/angular/)

## API

The grid exposes API methods to expand or collapse groups programmatically.

| Property | Type | Required | Default | Description |
| --- | --- | --- | --- | --- |
| `expandAll` | `Function` |  |  | Expand all groups. Modules (any of): [`ClientSideRowModelApiModule`](https://www.ag-grid.com/angular-data-grid/modules/), [`ServerSideRowModelApiModule`](https://www.ag-grid.com/angular-data-grid/modules/). |
| `collapseAll` | `Function` |  |  | Collapse all groups. Modules (any of): [`ClientSideRowModelApiModule`](https://www.ag-grid.com/angular-data-grid/modules/), [`ServerSideRowModelApiModule`](https://www.ag-grid.com/angular-data-grid/modules/). |
| `setRowNodeExpanded` | `Function` |  |  | Expand or collapse a specific row node, optionally expanding/collapsing all of its parent nodes. By default rows are expanded asynchronously for best performance. Set `forceSync: true` if you need to interact with the expanded row immediately after this function. Module: [`RowApiModule`](https://www.ag-grid.com/angular-data-grid/modules/). |

### Expand Row Ancestors

When expanding rows via the API, the `setRowNodeExpanded` function can be used to expand a specific row as well as all of its ancestors.

#### Expand to Row

```ts
import { Component } from "@angular/core";
import { AgGridAngular } from "ag-grid-angular";
import {
  AutoGroupColumnDef,
  ClientSideRowModelModule,
  ColDef,
  ColGroupDef,
  GetDataPath,
  GetRowIdFunc,
  GridApi,
  GridOptions,
  GridReadyEvent,
  ModuleRegistry,
  RowApiModule,
  TextFilterModule,
  enableDevValidations,
} from "ag-grid-community";
import { TreeDataModule } from "ag-grid-enterprise";
import { getData } from "./data";
if (process.env.NODE_ENV !== "production") {
  enableDevValidations();
}

ModuleRegistry.registerModules([
  RowApiModule,
  ClientSideRowModelModule,
  TreeDataModule,
  TextFilterModule,
]);

@Component({
  selector: "my-app",
  standalone: true,
  imports: [AgGridAngular],
  template: `<ag-grid-angular
    style="width: 100%; height: 100%;"
    [columnDefs]="columnDefs"
    [defaultColDef]="defaultColDef"
    [autoGroupColumnDef]="autoGroupColumnDef"
    [rowData]="rowData"
    [treeData]="true"
    [getDataPath]="getDataPath"
    [getRowId]="getRowId"
    (gridReady)="onGridReady($event)"
  /> `,
})
export class AppComponent {
  columnDefs: ColDef[] = [
    { field: "created" },
    { field: "modified" },
    {
      field: "size",
      aggFunc: "sum",
      valueFormatter: (params) => {
        const sizeInKb = params.value / 1024;
        if (sizeInKb > 1024) {
          return `${+(sizeInKb / 1024).toFixed(2)} MB`;
        } else {
          return `${+sizeInKb.toFixed(2)} KB`;
        }
      },
    },
  ];
  defaultColDef: ColDef = {
    flex: 1,
    minWidth: 100,
    filter: true,
  };
  autoGroupColumnDef: AutoGroupColumnDef = {
    headerName: "File Explorer",
    minWidth: 280,
    filter: "agTextColumnFilter",
    cellRendererParams: {
      suppressCount: true,
    },
  };
  rowData: any[] | null = getData();
  getDataPath: GetDataPath = (data) => data.path;
  getRowId: GetRowIdFunc = (params) =>
    params.data.path[params.data.path.length - 1];

  onGridReady(params: GridReadyEvent) {
    const node = params.api.getRowNode("Proposal.docx");
    if (node) {
      params.api.setRowNodeExpanded(node, true, true);
    }
  }
}
```

[Live example: Expand to Row](https://www.ag-grid.com/examples/tree-data-opening-groups/expand-collapse-api/angular/)

The example above uses [Row IDs](https://www.ag-grid.com/angular-data-grid/row-ids/#row-ids) to demonstrate the following configuration to expand all of the 'Proposal.docx' row's ancestors:

```
const expandToRow = () => {
  const node = gridApi.getRowNode('Proposal.docx');
  if (node) {
      gridApi.setRowNodeExpanded(node, true, true);
  }
}
```