---
url: /process-functions/mapping-findfirstusingright.md
description: Finds the first mapping row that matches the given right keys.
---

# mapping.findFirstUsingRight

Finds the first mapping row that matches the given right keys. Use it when you expect at most one match. To get every match, use [mapping.findUsingRight](/process-functions/mapping-findusingright).

```js
mapping.findFirstUsingRight(mappingName, rightKeys)
```

## Parameters

| Parameter | Type | Description |
|---|---|---|
| `mappingName` | `string` | The mapping's name or id. |
| `rightKeys` | `string[]` | One element for each dimension on the right side, in order. |

## Returns

The row as a JSON string, with its `id`, `left` keys and `right` keys. Use `JSON.parse()` to read it. Returns `null` when no row matches or the mapping can't be found.

## Examples

::: code-group

```js [find.js]
const row = JSON.parse(mapping.findFirstUsingRight("Time to Year and Month", ["2017", "Jul"]));
```

```json [Result]
{
    "id": 1,
    "left": ["FY2017 - Jul"],
    "right": ["2017", "Jul"]
}
```

:::

## Related

* [mapping.findUsingRight](/process-functions/mapping-findusingright): returns every row that matches.
* [mapping.findFirstUsingLeft](/process-functions/mapping-findfirstusingleft): looks up the other way.