To set the ID from a Substream to the request's body data, you can follow these steps: 1. Add a user input as a secret field on the "User inputs" page (e.g., named

api_key

). 2. On the stream page, add a new "Request parameter". 3. As key, configure the name of the query parameter the API requires (e.g., named

key

). 4. As value, configure a [placeholder](https://docs.airbyte.com/connector-development/config-based/understanding-the-yaml-file/reference#variables) for the created user input (e.g.,

{{ config['api_key'] }}

). This approach can be used to add the token to the request body. You can find more information about this in the [Other authentication methods](https://docs.airbyte.com/connector-development/connector-builder-ui/authentication#access-token-as-query-or-body-parameter) section of the documentation. For more advanced use cases, you can use the [ParentStreamConfig object](https://docs.airbyte.com/connector-development/config-based/understanding-the-yaml-file/reference#parentstreamconfig-object) to configure how to construct partitions from the records retrieved from the parent stream. This includes setting the parent_key, stream, partition_field, and request_option properties. Remember that this approach is for APIs that do not use one of the natively supported authentication methods. If your API uses a supported method, you can follow the instructions in the [API Key](https://docs.airbyte.com/connector-development/connector-builder-ui/authentication#api-key) section of the documentation.