# Update Unit Of Measure Group

`PATCH /inventory/unit-of-measure-groups/{id}`

Group: Inventory › Unit of Measure Groups · Operation ID: `updateUnitOfMeasureGroup`

Updates the unit of measure group with the given identifier. Only the fields in the request body change.

Everything omitted from the request body is left as it was. The conversion lines are edited through three arrays. createLines adds new lines, each with no id. updateLines changes existing lines, each keyed by its id. deleteLines removes lines by id. Omit all three to leave the conversion table unchanged. The arrays apply in the order delete, update, create, so one call can free a unit of measure and re-add it with a different factor. The base unit cannot be changed. The response is only the group's id. Read the updated group with GET inventory/unit-of-measure-groups/:id when you need its state after the update, including the ids of any lines you created.

[Open in the interactive reference](https://docs.api.lensing.ai/?op=updateUnitOfMeasureGroup)

## Parameters

| Name | In | Type | Required | Description |
| --- | --- | --- | --- | --- |
| `Api-Version` | header | `"v1"` | yes | The API version this request targets, named by its public identifier. Required on every request; omitting it, or naming a version this company does not have, is answered with 400. This document describes version `v1`. |
| `Idempotency-Key` | header | string | no | An opaque caller-chosen string (1-255 characters) that makes this request safe to retry. Repeating the same key with an identical request body replays the original response instead of re-executing - but only once that original request succeeded; a failed attempt re-executes on retry. Repeating the key with a different body is answered with 422. A key still in flight is answered with 409 - as is a key whose original request was interrupted before it finished, for a few minutes afterwards, until that attempt is presumed dead. A completed response stays replayable for 24 hours. The key is scoped to the caller, not to the action: reusing it for a different action is answered with 409 or 422 rather than treated independently. On read actions this header is ignored. On write actions that cannot offer the guarantee it is answered with `400 IDEMPOTENCY_NOT_SUPPORTED` rather than silently ignored. |
| `id` | path | string | yes | The unique identifier for the unit of measure group to update. |

## Request body

Required, `application/json`: updateUnitOfMeasureGroupInput.

| Field | Type | Required | Description |
| --- | --- | --- | --- |
| `name` | string | no | The display name of the unit of measure group. Omit to leave unchanged. It is not checked for uniqueness. |
| `description` | string | no | A free-form description of what the group covers. Omit to leave unchanged. |
| `createLines` | array of object | no | The conversion lines to add, each a full line with no id. A unit of measure the group already has a line for fails with DUPLICATE_UNIT_IN_GROUP, unless the same call also deletes that line, since deletes are applied first. |
| `createLines[].unitOfMeasureId` | string | yes | The unique identifier for the unit of measure this line converts. See id on GET inventory/unit-of-measures/:id. |
| `createLines[].conversionFactor` | string (decimal) | yes | How many base units of measure make up one of this unit. It must be greater than zero. |
| `updateLines` | array of object | no | The conversion lines to change, each keyed by its own id. The remaining fields are optional, and omitting one leaves it unchanged. A line id belonging to another group fails with LINE_NOT_FOUND. |
| `updateLines[].id` | string | yes | The unique identifier for the conversion line to change. Read it from the line's id on GET inventory/unit-of-measure-groups/:id, not the unit's id. |
| `updateLines[].conversionFactor` | string (decimal) | no | How many base units of measure make up one of this line's unit. Omit to leave unchanged. It must be greater than zero. |
| `deleteLines` | array of string | no | The unique identifiers for the conversion lines to remove. They are removed before createLines is applied, so one call can free a unit of measure and re-add it with a different factor. Removing every line, the base unit's included, leaves a group that has forgotten its base unit and can take no new lines. |

Example:

```json
{
  "name": "<name>",
  "description": "<description>",
  "createLines": [
    {
      "unitOfMeasureId": "d1f7b204-53ea-4c98-8b16-7f420e93ac57",
      "conversionFactor": "480.00"
    }
  ],
  "updateLines": [
    {
      "id": "3fa85f64-5717-4562-b3fc-2c963f66afa6",
      "conversionFactor": "19.99"
    }
  ],
  "deleteLines": [
    "<deleteLines>"
  ]
}
```

## Response

`200` Success

Under `data` (updateUnitOfMeasureGroupOutput):

| Field | Type | Required | Description |
| --- | --- | --- | --- |
| `id` | string | yes | The unique identifier for the unit of measure group. |

## Response headers

- `Idempotency-Replayed` — Present and `true` only when this response replays a previously stored one for the same Idempotency-Key, rather than reflecting a live execution. Absent on a live response - never sent as `false`.

## Errors

| Code | Status |
| --- | --- |
| `NOT_FOUND` | 400 |
| `UNIT_NOT_FOUND` | 400 |
| `DUPLICATE_UNIT_IN_GROUP` | 400 |
| `LINE_NOT_FOUND` | 400 |
| `INVALID_CONVERSION_FACTOR` | 400 |
| `IDEMPOTENCY_KEY_CONFLICT` | 409 |
| `IDEMPOTENCY_PAYLOAD_MISMATCH` | 422 |

## Statuses

- `400` — Invalid request or business failure. Codes: NOT_FOUND, UNIT_NOT_FOUND, DUPLICATE_UNIT_IN_GROUP, LINE_NOT_FOUND, INVALID_CONVERSION_FACTOR
- `401` — Missing or invalid access token
- `403` — Not authorized
- `404` — Not found
- `409` — The Idempotency-Key is still being processed by another request.
- `422` — The Idempotency-Key was already used with a different request payload.
- `429` — Too many requests
- `500` — Internal server error