# Retrieve the references of a specific policy entry

`GET /api/2/policies/{policyId}/entries/{label}/references`

Returns the references of the policy entry identified by the
`policyId` path parameter and the `label` path parameter.

References define links to other policy entries, optionally from imported policies.
Each reference object contains a required `entry` field (the label of the referenced entry)
and an optional `import` field (the policy ID of the import to reference from).

Authentication (security requirement alternatives):

```json
[
  {
    "OpenIDConnect": []
  },
  {
    "NginxBasic": []
  },
  {
    "Bearer": []
  }
]
```

- OpenIDConnect: openIdConnect. OpenID Connect Discovery URL. The placeholder is replaced by Swagger UI when configured.
- NginxBasic: http (basic). Eclipse Ditto sandbox demo user (demo1 ... demo9) + password (demo)
- Bearer: http (bearer). A JSON Web Token issued by a supported OAuth 2.0 Identity Provider.

Parameters:

- `policyId` (path, string, required) - The ID of the policy needs to follow the namespaced entity ID notation (see [Ditto documentation on namespaced entity IDs](https://www.eclipse.dev/ditto/basic-namespaces-and-names.html#namespaced-id)).

The namespace needs to:
* conform to the reverse domain name notation
  Type: string

- `label` (path, string, required) - The label of a policy entry
  Type: string

- `If-Match` (header, string, optional) - The `If-Match` header which has to conform to RFC-7232 (Conditional Requests). Common usages are:
  * optimistic locking by specifying the `ETag` from a previous HTTP response, e.g. `If-Match: "hash:a75ece4e"`
  * retrieving or modifying a resource only if it already exists, e.g. `If-Match: *`
  Type: string

- `If-None-Match` (header, string, optional) - The `If-None-Match` header, which has to conform to RFC-7232 (Conditional Requests). A common usage scenario is to modify a resource only if it does not yet exist, thus to create it, by specifying `If-None-Match: *`.
  Type: string

- `timeout` (query, string, optional) - Defines how long the backend should wait for completion of the request, e.g. applied when waiting for requested
acknowledgements via the `requested-acks` param. Can be specified without unit (then seconds are assumed) or
together with `s`, `ms` or `m` unit. Example: `42s`, `1m`.

The default (if omitted) and maximum timeout is `60s`. A value of `0` applies fire and forget semantics for
the command resulting in setting `response-required=false`.
  Type: string

Responses:

- 200: The request successfully returned. The references are returned.

Content type: application/json

Type: Array<object>

An optional list of references to other policy entries. Each reference points to an entry
either in the same policy (local reference) or in an imported policy (import reference).
When set, subjects, resources, and namespaces from the referenced entries are additively
merged into this entry.

* Import reference: contains both `entry` (the label) and `import` (the policy ID of the imported policy)
* Local reference: contains only `entry` (the label of another entry in the same policy)

Schema: [References](https://sourcey-ditto.pages.dev/http-api-doc/models/references.md)

Example:

```json
[
  {
    "entry": "operator",
    "import": "energy-corp:power-plant-roles"
  },
  {
    "entry": "local-admin"
  }
]
```

Items:
  Type: object
  
  A single reference to a policy entry.
  
  - `entry` (required)
    Type: string
    
    The label of the referenced entry.
  
  - `import` (optional)
    Type: string
    
    The ID of the imported policy this reference points to.
    If absent, the reference points to a local entry within the same policy.

- 304: The (sub-)resource has not been modified. This happens when you specified a If-None-Match header which
 matches the current ETag of the (sub-)resource.

- 400: The request could not be completed. Possible reasons:

  * the `policyId` does not conform to the namespaced entity ID notation (see [Ditto documentation on namespaced entity IDs](https://www.eclipse.dev/ditto/basic-namespaces-and-names.html#namespaced-id))

Content type: application/json

Type: AdvancedError

Schema: [AdvancedError](https://sourcey-ditto.pages.dev/http-api-doc/models/advancederror.md)

- `status` (required)
  Type: integer
  
  The HTTP status of the error

- `error` (required)
  Type: string
  
  The error code of the occurred exception

- `message` (required)
  Type: string
  
  The message of the error - what went wrong

- `description` (optional)
  Type: string
  
  A description how to fix the error or more details

- `href` (optional)
  Type: string
  
  A link to further information about the error and how to fix it

- 401: The request could not be completed due to missing authentication.

Content type: application/json

Type: AdvancedError

Schema: [AdvancedError](https://sourcey-ditto.pages.dev/http-api-doc/models/advancederror.md)

- `status` (required)
  Type: integer
  
  The HTTP status of the error

- `error` (required)
  Type: string
  
  The error code of the occurred exception

- `message` (required)
  Type: string
  
  The message of the error - what went wrong

- `description` (optional)
  Type: string
  
  A description how to fix the error or more details

- `href` (optional)
  Type: string
  
  A link to further information about the error and how to fix it

- 404: The request could not be completed. The policy with the given ID or
the policy entry was not found in the context of the authenticated
user.

Content type: application/json

Type: AdvancedError

Schema: [AdvancedError](https://sourcey-ditto.pages.dev/http-api-doc/models/advancederror.md)

- `status` (required)
  Type: integer
  
  The HTTP status of the error

- `error` (required)
  Type: string
  
  The error code of the occurred exception

- `message` (required)
  Type: string
  
  The message of the error - what went wrong

- `description` (optional)
  Type: string
  
  A description how to fix the error or more details

- `href` (optional)
  Type: string
  
  A link to further information about the error and how to fix it

- 412: A precondition for reading or writing the (sub-)resource failed. This will happen for write requests, if you
specified an If-Match or If-None-Match header, which fails the precondition check against the current ETag of
the (sub-)resource. For read requests, this error may only happen for a failing If-Match header. In case of a
failing If-None-Match header for a read request, status 304 will be returned instead.

Content type: application/json

Type: AdvancedError

Schema: [AdvancedError](https://sourcey-ditto.pages.dev/http-api-doc/models/advancederror.md)

- `status` (required)
  Type: integer
  
  The HTTP status of the error

- `error` (required)
  Type: string
  
  The error code of the occurred exception

- `message` (required)
  Type: string
  
  The message of the error - what went wrong

- `description` (optional)
  Type: string
  
  A description how to fix the error or more details

- `href` (optional)
  Type: string
  
  A link to further information about the error and how to fix it

## Examples

### cURL

```bash
curl -X GET 'https://ditto.eclipseprojects.io/api/2/policies/string/entries/string/references' \
  -H 'Authorization: Bearer YOUR_TOKEN'
```

### JavaScript

```javascript
const response = await fetch('https://ditto.eclipseprojects.io/api/2/policies/string/entries/string/references', {
  method: 'GET',
  headers: {
    'Authorization': 'Bearer YOUR_TOKEN',
  },
});

const data = await response.text();
```

### Python

```python
import requests

response = requests.get(
    'https://ditto.eclipseprojects.io/api/2/policies/string/entries/string/references',
    headers={
        'Authorization': 'Bearer YOUR_TOKEN',
    },
)
print(response.text)
```