Edits history of script submission #11449 for ' MQTT trigger script template (windmill)'

• bun

  Edit in Windmill

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  /**
   * MQTT Preprocessor Function
   * 
   * This function is called when an MQTT message is received, BEFORE your main handler function.
   * It allows you to transform or validate the incoming data before processing.
   * 
   * Flow: MQTT message → preprocessor function → main function
   * 
   * IMPORTANT: The object you return from this preprocessor determines the parameters passed to your main function:
   * - If you return {a: 1, b: 2}, then main will be called as main(a, b)
   * - If you return {payload}, then main will be called as main(payload)
   * - If you return nothing or {}, then main will only receive the raw payload as main(payload)
   * 
   * @param wm_trigger - Information about the trigger source (MQTT in this case)
   * @param payload - The raw bytes of the MQTT message (as Uint8Array)
   * @returns An object with the arguments to pass to the main function
   */
  export async function preprocessor(
    wm_trigger: {
      kind: 'http' | 'email' | 'webhook' | 'websocket' | 'kafka' | 'nats' | 'postgres' | 'sqs' | 'mqtt',
      mqtt: {
        topic: string,
        retain: boolean,
        pkid: number,
        qos: number,
        v5?: {
          payload_format_indicator?: number,
          topic_alias?: number,
          response_topic?: string,
          correlation_data?: Array<number>,
          user_properties?: Array<[string, string]>,
          subscription_identifiers?: Array<number>,
          content_type?: string
        }
      }
    },
    /**
     * The raw message payload from the MQTT broker as bytes
     * This preprocessor function is called before your main function
     * The object you return from this function will be passed as arguments to your main function
     * You can transform the payload here before it reaches your main handler
     */
    payload: Uint8Array,
  ) {
    return {
      content_type: wm_trigger.mqtt.v5?.content_type,
      payload,
      payloadAsString: new TextDecoder().decode(payload)
    }
  }
  
  /**
   * Main Function - Handles MQTT Messages
   * 
   * This function receives arguments based on what was returned by the preprocessor:
   * - If preprocessor returns {payload, content_type}, main is called as main(payload, content_type)
   * - If preprocessor returns {payload, someValue}, main is called as main(payload, someValue)
   * - If preprocessor returns {}, main is called as main(payload) with the raw payload only
   * 
   * IMPORTANT: 
   * - The 'payload' parameter will always be available to the main function
   * - Any other parameters only exist if explicitly returned from the preprocessor
   * - There are no "special" parameters - all additional parameter names come directly 
   *   from what you return in the preprocessor
   * 
   * @param content_type - The content type from MQTT v5 properties if available
   * @param payload - The raw binary payload from MQTT
   * @param payloadAsString - The payload converted to a string
   * @returns The result of processing the MQTT message
   */
  export async function main(payload: string, content_type?: string, payloadAsString: string) {
  
  }

  Submitted by dieriba.pro916 442 days ago