# ExternalDataColumn

Canonical page: https://www.adaptabletools.com/docs/reference/externaldatacolumn

dataType metadata for external-data keys that are not grid columns.
When a `columnId` is both a grid column and listed here, this override wins.

```ts title="TypeScript"
export interface ExternalDataColumn 
```

## Properties

| Property | Type | Description |
| --- | --- | --- |
| [columnId](https://www.adaptabletools.com/docs/reference/externaldatacolumn.md#columnid) | `string` | Key on the plain-object row this metadata describes. Matches a grid `colId` when the key is also a column. |
| [dataType](https://www.adaptabletools.com/docs/reference/externaldatacolumn.md#datatype) | `'number' \| 'text' \| 'date' \| 'boolean' \| 'array'` | How to treat the value. When this key is also a grid column, this type wins over the column's data type. |

## Property Details

### columnId

Key on the plain-object row this metadata describes. Matches a grid `colId` when the key is also a column.

```ts title="TypeScript"
columnId: string;
```

###### Property Value

`string`

### dataType

How to treat the value. When this key is also a grid column, this type wins over the column's data type.

```ts title="TypeScript"
dataType?: 'number' | 'text' | 'date' | 'boolean' | 'array';
```

###### Property Value

`'number' | 'text' | 'date' | 'boolean' | 'array'`