Custom API Calls allow the user to send a request to a specific endpoint if no action has been implemented for it. This will show in the actions list of the piece as Custom API Call, to enable this action for a piece, you need to call the createCustomApiCallAction in your actions array.

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Basic Example

The example below implements the action for the OpenAI piece. The OpenAI piece uses a Bearer token authorization header to identify the user sending the request. 
actions: [
  ...yourActions,
  createCustomApiCallAction({
    // The auth object defined in the piece
    auth: openaiAuth,
    // The base URL for the API
    baseUrl: () => {
      'https://api.openai.com/v1'
    },
    // Mapping the auth object to the needed authorization headers
    authMapping: (auth) => {
      return {
        'Authorization': `Bearer ${auth}`
      }
    }
  })
]

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Dynamic Base URL and Basic Auth Example

The example below implements the action for the Jira Cloud piece. The Jira Cloud piece uses a dynamic base URL for it’s actions, where the base URL changes based on the values the user authenticated with. We will also implement a Basic authentication header. 
actions: [
  ...yourActions,
  createCustomApiCallAction({
    baseUrl: (auth) => {
      return `${(auth as JiraAuth).instanceUrl}/rest/api/3`
    },
    auth: jiraCloudAuth,
    authMapping: (auth) => {
      const typedAuth = auth  as JiraAuth
      return {
        'Authorization': `Basic ${typedAuth.email}:${typedAuth.apiToken}`
      }
    }
  })
]