# setColumnGroupOpened

Expands or collapses the specified column group header.

Canonical: https://grid.syidax.com/docs/methods/setColumnGroupOpened/

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## What does this API do?

Expands or collapses the specified column group header.

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## Exact input and result types

```typescript
setColumnGroupOpened(groupId: string, open: boolean): Promise<void>
```

| Arguments | Required | Type |
| --- | --- | --- |
| groupId | Required | string |
| open | Required | boolean |

The return type is `Promise<void>`.

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## Usage flow

After registering and initializing the Grid element, call grid.setColumnGroupOpened(…). Read the return value with await. For methods returning a boolean or report, inspect the result before continuing.

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## Feature explanations and examples

- [Multi-level headers](https://grid.syidax.com/docs/features/column-groups.md) — Multi-level headers place related columns under a shared heading. Unlike row grouping, they do not change data counts or aggregate values.