Hello Nivetha, 
Have you tried the old way?

import base64

pdf = self.env['report'].sudo().get_pdf([invoice.id], 'account.report_invoice')
self.env['ir.attachment'].create({
    'name': 'Cats',
    'type': 'binary',
    'datas': base64.encodestring(pdf),
    'res_model': 'account.invoice',
    'res_id': invoice.id,
    'mimetype': 'application/x-pdf'
})

If you need more explanation go with this tutorial
https://www.cybrosys.com/blog/creating-pdf-attachment-automatically-odoo-13

Or older one:

https://medium.com/hendrasj/how-to-create-attachment-pdf-report-automatically-on-odoo-10-odoo-11-79dd3ad19f23

You will find a way that should work for you also in Odoo 15.


I you found it helpful please vote +1 👍
If it solves completely you problem - mark as best answer 😎

Hi,

Try refer the following number.

https://www.cybrosys.com/blog/how-to-create-pdf-attachment-automatically-in-odoo-15

Regards

Api to get pdf file preview:

@http.route(['/schedule_pdf'], type='http', auth="public", website=True, sitemap=False)
def schedule_pdf(self, **kw):         
​if kw.get('id'):      
​ ​as_model = request.env['alwathba.schedule'].sudo().browse([int(kw.get('id'))])
​         content = base64.b64decode(str(as_model.pdf_file.decode("utf-8")))     
​ ​pdfhttpheaders = [('Content-Type', 'application/pdf'),('Content-Length', u'%s' % len(content))]      
​ ​return request.make_response(content, headers=pdfhttpheaders) 



to access pdf: https://yourcompany.com/schedule_pdf?id=14