# ColumnGroupDef

Fields, allowed values, and APIs that use ColumnGroupDef.

Canonical: https://grid.syidax.com/docs/types/ColumnGroupDef/

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## Type definition

A question mark (?) marks an optional field; readonly marks a value you should not change directly. A union (|) accepts one of the listed forms. Functions are callbacks that Grid invokes at the relevant point.

```typescript
export interface ColumnGroupDef<TLeaf extends GroupableLeaf = GroupableLeaf> {
  headerName: string;
  groupId?: string;
  children: ReadonlyArray<TLeaf | ColumnGroupDef<TLeaf>>;
}
```

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## Contracts containing this type

- [GridColumnGroupDef](https://grid.syidax.com/docs/types/GridColumnGroupDef.md)

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## Related types

- [GroupableLeaf](https://grid.syidax.com/docs/types/GroupableLeaf.md)