File Upload with GPT Action Calling API Endpoint

GPT builders
1

Hello,

I’m currently trying to create a GPT with an action that should call an API endpoint and upload a file provided by the user. Here’s the OpenAPI schema I’m using:

openapi: 3.1.0
info:
  title: DOCX to PDF
  description: API for converting DOCX to PDF files
  version: 1.0.0
servers:
  - url: https://v2.convertapi.com
paths:
  /convert/docx/to/pdf:
    post:
      operationId: convertDocxToPdf
      summary: Uploads file in multipart/form-data
      description: Uploads file and converts DOCX to a PDF file
      tags:
        - Conversion
      requestBody:
        required: true        
        content:
          multipart/form-data:
            schema:
              type: object
              properties:
                file:
                  type: string
                  format: binary
      responses:
        "200":
          content:
            application/pdf:
              schema:
                type: string
                format: binary

However, when this action is called, the API is being hit with a JSON payload instead of a proper multipart/form-data request, and the file upload fails.

Could you please advise how to properly handle the file upload in this context, so the user-provided file is sent correctly as multipart/form-data?

Thank you in advance for your help!