> ## Documentation Index
> Fetch the complete documentation index at: https://wiki.another-horizon.eu/llms.txt
> Use this file to discover all available pages before exploring further.

# Complex data types

> Describe APIs with flexible schemas, optional properties, and multiple data formats using `oneOf`, `anyOf`, and `allOf` keywords.

When your API accepts multiple data formats, has conditional fields, or uses inheritance patterns, OpenAPI's schema composition keywords help you document these flexible structures. Using `oneOf`, `anyOf`, and `allOf`, you can describe APIs that handle different input types or combine multiple schemas into comprehensive data models.

## `oneOf`, `anyOf`, `allOf` keywords

For complex data types, OpenAPI provides keywords for combining schemas:

* `allOf`: Combines multiple schemas (like merging objects or extending a base schema). Functions like an `and` operator.
* `anyOf`: Accepts data matching any of the provided schemas. Functions like an `or` operator.
* `oneOf`: Accepts data matching exactly one of the provided schemas. Functions like an `exclusive-or` operator.

<Warning>Mintlify treats `oneOf` and `anyOf` identically since the practical difference rarely affects using the API.</Warning>

For detailed specifications of these keywords see the [OpenAPI documentation](https://swagger.io/docs/specification/data-models/oneof-anyof-allof-not/).

<Info>The `not` keyword is currently unsupported.</Info>

### Combining schemas with `allOf`

When you use `allOf`, Mintlify performs some preprocessing on your OpenAPI document to display complex combinations in a readable way. For example, when you combine two object schemas with `allOf`, Mintlify combines the properties of both into a single object. This becomes especially useful when leveraging OpenAPI's reusable [components](https://swagger.io/docs/specification/components/).

```yaml theme={null}
org_with_users:
  allOf:
    - $ref: '#/components/schemas/Org'
    - type: object
      properties:
        users:
          type: array
          description: An array containing all users in the organization
# ...
components:
  schemas:
    Org:
      type: object
      properties:
        id:
          type: string
          description: The ID of the organization
```

<ParamField body="org_with_users" type="object">
  <Expandable>
    <ParamField body="id" type="string">
      The ID of the organization
    </ParamField>

    <ParamField body="users" type="object[]">
      An array containing all users in the organization
    </ParamField>
  </Expandable>
</ParamField>

### Providing options with `oneOf` and `anyOf`

When you use `oneOf` or `anyOf`, the options are displayed in a tabbed container. Specify a `title` field in each subschema to give your options names. For example, here's how you might display two different types of delivery addresses:

```yaml theme={null}
delivery_address:
  oneOf:
    - title: StreetAddress
      type: object
      properties:
        address_line_1:
          type: string
          description: The street address of the recipient
        # ...
    - title: POBox
      type: object
      properties:
        box_number:
          type: string
          description: The number of the PO Box
        # ...
```

<ParamField body="delivery_address" type="object">
  <div className="mt-4 rounded-xl border border-gray-100 px-4 pb-4 pt-2 dark:border-white/10">
    <Tabs>
      <Tab title="StreetAddress">
        <ParamField body="address_line_1" type="string">
          The street address of the residence
        </ParamField>
      </Tab>

      <Tab title="POBox">
        <ParamField body="box_number" type="string">
          The number of the PO Box
        </ParamField>
      </Tab>
    </Tabs>
  </div>
</ParamField>