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path_to_agent_file: "https://agents.1health.io/public/demo/api/v3/custom-data/definition/type/agents.md"
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methods: [GET]
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how_to: "https://agents.1health.io/public/demo/api/v3/custom-data/definition/type/how-to.md"
use_case: "https://agents.1health.io/public/demo/api/v3/custom-data/definition/type/use-case.md"
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---

# /v3/custom-data/definition/type

**URL**: https://demo.1health.io/api/v3/custom-data/definition/type

APIs for defining custom fields on a business object class. Supports creating, replacing, partially updating, and retiring definitions. The tenant and application are resolved from the authenticated context; storage slots are allocated automatically.

## Endpoints

| Endpoint | Method | Description |
| --- | --- | --- |
| /v3/custom-data/definition/type/{typeKey} | GET | List custom data definitions for a business object class |

---

## GET /v3/custom-data/definition/type/{typeKey}

List custom data definitions for a business object class

### Overview

**Overview**: Returns all custom data definitions (each with its fields) visible to the caller for the given business object class, within the authenticated tenant and application context.

**Behavior & Use Cases**:
- Results are scoped to the authenticated tenant and application
- Only client-facing metadata is returned; the physical storage slot is not exposed
- `typeKey` must reference an existing business object class
- Returns an empty list when the class exists but has no custom data definitions

**Important Notes**:
- Requires authentication; the target application is taken from the authenticated application context or from an explicit `appId` (see the `appId` parameter)

### Authorization

Bearer JWT required. See the [authentication guide](https://agents.1health.io/public/demo/api/authentication/agents.md).

### Path Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| typeKey | String | Yes | The key of the business object class whose custom data definitions should be returned. |

### Query Parameters

| Parameter | Type | Required | Default | Description |
| --- | --- | --- | --- | --- |
| appId | Long | No |  | External application the custom data belongs to. Optional; when omitted, the application is resolved from the authenticated context. Custom data definitions belong to the application's owner tenant: creating, updating or deleting them requires being a system administrator of that owner tenant, while reading them is allowed for the owner and any tenant the application is visible to (public, or explicitly allowed for a private application). A request with neither an application context nor an explicit appId is rejected. |

### Responses

#### 200 OK

Custom data definitions retrieved successfully.

**DTO**: `CustomDataDefinitionListResponseDTO`

```json
{
  "definitions": [
    {}
  ]
}
```

| Field | Type | Nullable | Description |
| --- | --- | --- | --- |
| definitions | List<CustomDataDefinitionResponseDTO> | No | The custom data definitions visible to the caller for the requested business object class. |

#### 400 Bad Request

Invalid request. Possible causes:
• `typeKey` does not reference an existing business object class
• Missing external application context

#### 401 Unauthorized

Not authenticated — valid session required.

### Example

```bash
curl -X GET "https://demo.1health.io/api/v3/custom-data/definition/type/example-value" \
  -H "Authorization: Bearer $TOKEN"
```

---

## Navigation
Parent: https://agents.1health.io/public/demo/api/v3/custom-data/definition/agents.md · Site guide: https://agents.1health.io/public/demo/api/agents.md