> ## Documentation Index > Fetch the complete documentation index at: https://docs.gumnut.ai/llms.txt > Use this file to discover all available pages before exploring further. # Update metadata on multiple assets > Updates metadata on multiple assets in one transactional call. Each item carries the target asset id and the per-asset change — different fields can be changed on different assets in the same request. Atomic: any per-item validation failure or unknown / cross-user id rejects the whole batch and writes nothing. Up to 100 items per request; over-cap requests return 422. For a single-asset edit, prefer `update_asset` — semantically identical but slightly more concise at the call site. ## OpenAPI ````yaml https://api.gumnut.ai/openapi.json post /api/assets/bulk-update openapi: 3.1.0 info: title: Gumnut API description: API for using Gumnut to manage photos and videos version: 0.1.0 servers: [] security: [] paths: /api/assets/bulk-update: post: tags: - assets summary: Update metadata on multiple assets description: >- Updates metadata on multiple assets in one transactional call. Each item carries the target asset id and the per-asset change — different fields can be changed on different assets in the same request. Atomic: any per-item validation failure or unknown / cross-user id rejects the whole batch and writes nothing. Up to 100 items per request; over-cap requests return 422. For a single-asset edit, prefer `update_asset` — semantically identical but slightly more concise at the call site. operationId: bulk_update_assets requestBody: content: application/json: schema: $ref: '#/components/schemas/BulkUpdateAssetsRequest' required: true responses: '200': description: Successful Response content: application/json: schema: $ref: '#/components/schemas/BulkUpdateAssetsResponse' '404': description: Not found '422': description: Validation Error content: application/json: schema: $ref: '#/components/schemas/HTTPValidationError' components: schemas: BulkUpdateAssetsRequest: properties: updates: items: $ref: '#/components/schemas/BulkUpdateAssetItem' type: array maxItems: 100 minItems: 1 title: Updates description: >- List of per-asset updates. Each item carries the target asset id and the change to apply to it; different fields can be changed on different assets in the same request. Up to 100 items per request. type: object required: - updates title: BulkUpdateAssetsRequest description: Bulk-update request body — heterogeneous per-asset changes in one call. BulkUpdateAssetsResponse: properties: {} type: object title: BulkUpdateAssetsResponse description: |- Acknowledgment body for ``POST /api/assets/bulk-update``. Empty by design; exists so MCP tools generated from this endpoint have a real ``outputSchema``. Distinct from ``DeletionResponse`` because that name is purpose-scoped to destructive operations — reusing it on a non-destructive endpoint would misname the wire shape in OpenAPI and generated SDKs. x-stainless-empty-object: true HTTPValidationError: properties: detail: items: $ref: '#/components/schemas/ValidationError' type: array title: Detail type: object title: HTTPValidationError BulkUpdateAssetItem: properties: id: type: string title: Id description: >- Asset ID (with the `asset_` prefix) to apply this change to. Obtain from `list_assets`, `search_assets`, or `list_album_assets`. change: $ref: '#/components/schemas/UpdateAssetRequest' description: >- The change to apply to this asset. Same shape as the body of the single-asset `update_asset` endpoint — same fields, same validation, same null-clears-the-override semantics. type: object required: - id - change title: BulkUpdateAssetItem description: |- One item in a bulk-update request. Names the target asset and carries the per-asset change to apply. The ``change`` object is exactly the body shape that the single-asset ``PATCH /api/assets/{asset_id}`` endpoint accepts; the wrapper exists so operation-level metadata (``id``, future ``if_match`` / idempotency-key fields) stays in a namespace disjoint from the entity-field changes. ValidationError: properties: loc: items: anyOf: - type: string - type: integer type: array title: Location msg: type: string title: Message type: type: string title: Error Type input: title: Input ctx: type: object title: Context type: object required: - loc - msg - type title: ValidationError UpdateAssetRequest: properties: description: anyOf: - type: string - type: 'null' title: Description description: >- User-set description for the asset. Pass ``null`` to remove a previously-set value (the response then falls back to the description embedded in the file, if any). Omit to leave unchanged. Distinct from the AI-generated `description` field on the response — this writes to `metadata.description`. latitude: anyOf: - type: number - type: 'null' title: Latitude description: >- GPS latitude in decimal degrees, ``[-90, 90]``. Must be set together with ``longitude``. Pass ``null`` (along with ``longitude=null``) to remove a previously-set value; omit to leave unchanged. longitude: anyOf: - type: number - type: 'null' title: Longitude description: >- GPS longitude in decimal degrees, ``[-180, 180]``. Must be set together with ``latitude``. Pass ``null`` (along with ``latitude=null``) to remove a previously-set value; omit to leave unchanged. original_datetime: anyOf: - type: string format: date-time - type: 'null' title: Original Datetime description: >- When the asset was originally captured. Aware values store the offset from ``utcoffset()`` alongside; naive values store NULL offset. Pass ``null`` to remove a previously-set value — the response then falls back to the datetime embedded in the file when present, otherwise to the file's upload timestamp. Omit to leave unchanged. additionalProperties: true type: object title: UpdateAssetRequest description: >- User-editable metadata for a single asset. Mirrors the field shape of ``UserAssetMetadataUpdate``; the service model owns cross-field validation. See ``photos-api/docs/references/api-design.md`` for the router-DTO + service-model pattern. ````