Create Invoice Attachment using API call in Odoo 17

I am currently working on sending invoices via email using the Odoo 17 API from a Node.js server. I've managed to handle most of the tasks, but I encountered an issue when trying to send an invoice via email. Instead of being sent as an attachment, the invoice is included as a link in the email.

understand that to attach the invoice as a PDF file, I need to make an API call like this:

{
    "jsonrpc": "2.0",
    "method": "call",
    "params": {
        "service": "object",
        "method": "execute_kw",

        "args": [
            "{{db}}",
            "{{uid}}",
            "{{password}}",
            "ir.attachment",
            "create",
          [{
        "name": "Invoice.pdf", 
        "type": "binary",  
        "res_model": "account.move",
        "datas": "base64 data",
        "res_id": 17, 
        "mimetype": "application/pdf" 
      }]
        ]
    }
}

But first I need to somehow encode the data into base64 format. Is there an Odoo API method to directly encode the file? Or maybe it's possible that there's a setting in Odoo that could automatically add the invoice as an attachment when it's created, instead of manually handling the attachment via API?

Thanks in advance!

I think I can just use email templates. Then the attachment is being added automatically. The body of the API call is like this: { "jsonrpc": "2.0", "method": "call", "params": { "service": "object", "method": "execute_kw", "args": [ "{{db}}", "{{uid}}", "{{password}}", "mail.template", "send_mail", [12, 50], { "force_send": "True" } ] }, "id": 5 }