# Relations

## Create Annotation Relation

<mark style="color:green;">`POST`</mark> `https://api.annolab.ai/v1/relation/create`

Create a new relation between two annotations. If a relation of the type already exists between the two annotation ids, then the existing relation will be returned and a duplicate will not be created.

#### Headers

| Name          | Type   | Description                                                                                                                                                             |
| ------------- | ------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Authorization | string | <p>Where you put your api key. Creating a project requires a key with "Write" permissions.<br><br><code>{"Authorization": "Api-key XXXXXXX-XXXXXXX-XXXXXXX"}</code></p> |

#### Request Body

| Name               | Type    | Description                                                                                                                                                  |
| ------------------ | ------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| annoTypeIdentifier | string  | Identifier for the annotation type  of the relation. Either the id or the unique name. Must be an annotation type with isRelation: true or request will fail |
| projectIdentifier  | string  | Identifier of the project containing the layer. Either the id or the unique name.                                                                            |
| successorId        | integer | id of the annotation that is the child of the relation                                                                                                       |
| predecessorId      | integer | id of the annotation that is the parent of the relation                                                                                                      |
| value              | string  | value of the annotation                                                                                                                                      |

{% tabs %}
{% tab title="200 Relation already exists" %}

```
{
  "id": 72,
  "successorId": 44,
  "predecessorId": 12,
  "typeName": "Coreference",
  "typeId": 112,
  "value": '',
 }
```

{% endtab %}

{% tab title="201 Relation was successfully created" %}

```
{
  "id": 72,
  "successorId": 44,
  "predecessorId": 12,
  "typeName": "Coreference",
  "typeId": 112,
  "value": '',
 }
```

{% endtab %}

{% tab title="400 Relation creation failed" %}

```
{
    "message": "Information about why creation failed"
}
```

{% endtab %}
{% endtabs %}

Examples of how to make a layer create request

{% tabs %}
{% tab title="Python" %}

```python
import requests

ANNO_LAB_API_KEY = 'XXXXXXX-XXXXXXX-XXXXXXX-XXXXXXX'

relation = {
  'relationTypeName': 'Coreference',
  'projectIdentifier': 'New NER Project',
  'successorId': 112,
  'predecessorId': 141,
}

headers = {
  'Authorization': 'Api-Key '+ANNO_LAB_API_KEY,
}

url = 'https://api.annolab.ai/v1/relation/create'

response = requests.post(url, headers=headers, json=relation)

print(response.json())
```

{% endtab %}
{% endtabs %}


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.annolab.ai/annotations-and-relations/relations.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.