I have small model as below:

I am always getting error as here console.. Web shows internal server error. :

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return http.request.env['newgst.gstreturn']._gstr_response({'rec_id': rec_id})
  File "/opt/odoo/odoo-10.0/odoo/api.py", line 752, in __getitem__
    return self.registry[model_name]._browse((), self)
  File "/opt/odoo/odoo-10.0/odoo/modules/registry.py", line 174, in __getitem__
    return self.models[model_name]
KeyError: 'newgst.gstreturn'

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newgst : is my custom module
gstreturn : is my model

I wrote this referring to this answer:

https://stackoverflow.com/questions/42022416/generate-an-odoo-downloadable-csv-report

But unfortunately not able to make it working.. :(

Please please help.............Its total blocker for me.

class NewgstGstreturn(models.Model):
	_name = 'gstreturn'

	# _inherit = "account.invoice"

	@api.model
	def _gstr_response(self, vals):

		rec_id = vals.get('rec_id')
		_logger.warning('abhishek in _gstr_response')
		_logger.warning('abhishek - num (%d)', rec_id )

	
	def get_gstr_file(self):
		return {
		'type' : 'ir.actions.act_url',
		 		'url': '/web/Gstrdownload/csvdownload',
				'target': 'blank',

My controller as below:

# -*- coding: utf-8 -*- 
from openerp import http 
from openerp.http import request 
from openerp.addons.web.controllers.main import serialize_exception,content_disposition

import base64


class Gstrdownload(http.Controller):

	@http.route('/web/Gstrdownload/csvdownload/<int:rec_id>/', type='http',auth='user', website=True)
	def csvdownload(self, rec_id, **kw):
		return http.request.env['newgst.gstreturn']._gstr_response({'rec_id': rec_id})