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# customObjectUpdateFieldDefinition

Update a field definition.

Updates an existing field definition.

## Parameters

| Name             | Type                                            | Required | Description                                                                          |
| ---------------- | ----------------------------------------------- | -------- | ------------------------------------------------------------------------------------ |
| `fieldId`        | integer                                         | Yes      | The field definition ID (from customObjectListFieldDefinitions)                      |
| `entity_type`    | string                                          | No       | Entity type (ASSET, REQUEST, CUSTOM\_OBJECT). Set automatically based on endpoint.   |
| `type`           | string (enum, 18 values)                        | Yes      | The field type. Valid values: SHORT\_TEXT, LONG\_TEXT, RICH\_TEXT, NUMBER, DECIMAL,  |
| `display_name`   | string                                          | Yes      | Human-readable field label (e.g., "Visa Number", "Assigned Agent")                   |
| `reference_key`  | string                                          | No       | Machine-readable key. Auto-generated if not provided.                                |
| `required_field` | boolean                                         | No       | Whether this field is required when creating instances. Default: `False`.            |
| `hint`           | string                                          | No       | Placeholder/help text shown in the form input                                        |
| `order`          | integer                                         | No       | Display order in the form. Auto-assigned if not provided.                            |
| `options`        | object\[]                                       | No       | For DROPDOWN/MULTI\_DROPDOWN only. Valid option values.                              |
| `relationship`   | object                                          | No       | For RELATIONSHIP fields only. Target entity configuration.                           |
| `request_types`  | `SERVICE_REQUEST` \| `INCIDENT` \| `PROBLEM`\[] | No       | For adding fields to Requests only. Scopes which request types the field applies to. |
| `asset_settings` | object                                          | No       | For adding fields to Assets only. Specifies which asset types the field applies to.  |