[15.0] [BUG] account_invoice_fixed_discount by putting the same unit price amount in the fixed discount.

[JorgeQuinteros]

Module

account_invoice_fixed_discount

Describe the bug

ZeroDivisionError: float division by zero

If we set a fixed discount equal to the unit price or which gives as subtotal 0

Traceback (most recent call last):
  File "/opt/odoo/odoo/addons/base/models/ir_http.py", line 237, in _dispatch
    result = request.dispatch()
  File "/opt/odoo/odoo/http.py", line 698, in dispatch
    result = self._call_function(**self.params)
  File "/opt/odoo/odoo/http.py", line 368, in _call_function
    return checked_call(self.db, *args, **kwargs)
  File "/opt/odoo/odoo/service/model.py", line 94, in wrapper
    return f(dbname, *args, **kwargs)
  File "/opt/odoo/odoo/http.py", line 357, in checked_call
    result = self.endpoint(*a, **kw)
  File "/opt/odoo/odoo/http.py", line 921, in __call__
    return self.method(*args, **kw)
  File "/opt/odoo/odoo/http.py", line 546, in response_wrap
    response = f(*args, **kw)
  File "/opt/odoo/addons/web/controllers/main.py", line 1328, in call_button
    action = self._call_kw(model, method, args, kwargs)
  File "/opt/odoo/addons/web/controllers/main.py", line 1316, in _call_kw
    return call_kw(request.env[model], method, args, kwargs)
  File "/opt/odoo/odoo/api.py", line 464, in call_kw
    result = _call_kw_multi(method, model, args, kwargs)
  File "/opt/odoo/odoo/api.py", line 451, in _call_kw_multi
    result = method(recs, *args, **kwargs)
  File "/opt/odoo/addons/sale/models/account_move.py", line 76, in action_post
    res = super(AccountMove, self).action_post()
  File "/mnt/data/odoo-addons-dir/account_invoice_check_picking_date/models/account_move.py", line 65, in action_post
    return super().action_post()
  File "/mnt/data/odoo-addons-dir/account_move_exception/models/account_move.py", line 42, in action_post
    return super().action_post()
  File "/mnt/data/odoo-addons-dir/account_invoice_tax_required/models/account_move.py", line 54, in action_post
    return super(AccountMove, self).action_post()
  File "/mnt/data/odoo-addons-dir/account_invoice_force_number/models/account_move.py", line 36, in action_post
    return super(AccountMove, self).action_post()
  File "/mnt/data/odoo-addons-dir/account_invoice_check_total/models/account_move.py", line 57, in action_post
    return super().action_post()
  File "/opt/odoo/addons/account/models/account_move.py", line 3199, in action_post
    other_moves._post(soft=False)
  File "/opt/odoo/addons/sale/models/account_move.py", line 92, in _post
    posted = super()._post(soft)
  File "/opt/odoo/addons/purchase_stock/models/account_invoice.py", line 173, in _post
    return super()._post(soft)
  File "/opt/odoo/addons/stock_account/models/account_move.py", line 53, in _post
    posted = super()._post(soft)
  File "/mnt/data/odoo-addons-dir/account_invoice_supplier_self_invoice/models/account_move.py", line 65, in _post
    res = super()._post(soft=soft)
  File "/opt/odoo/addons/account_edi/models/account_move.py", line 502, in _post
    posted = super()._post(soft=soft)
  File "/opt/odoo/addons/account/models/account_move.py", line 3112, in _post
    move.with_context(check_move_validity=False)._onchange_invoice_date()
  File "/opt/odoo/addons/account/models/account_move.py", line 472, in _onchange_invoice_date
    self._onchange_currency()
  File "/opt/odoo/addons/account/models/account_move.py", line 552, in _onchange_currency
    self._recompute_dynamic_lines(recompute_tax_base_amount=True)
  File "/opt/odoo/addons/account/models/account_move.py", line 1177, in _recompute_dynamic_lines
    invoice._recompute_tax_lines(recompute_tax_base_amount=True)
  File "/mnt/data/odoo-addons-dir/account_invoice_triple_discount/models/account_move.py", line 34, in _recompute_tax_lines
    res = super(AccountMove, self)._recompute_tax_lines(**kwargs)
  File "/mnt/data/odoo-addons-dir/account_invoice_fixed_discount/models/account_move.py", line 18, in _recompute_tax_lines
    line.update({"price_unit": price_unit})
  File "/opt/odoo/odoo/models.py", line 5645, in update
    record[name] = value
  File "/opt/odoo/odoo/models.py", line 5925, in __setitem__
    return self._fields[key].__set__(self, value)
  File "/opt/odoo/odoo/fields.py", line 1242, in __set__
    records.write({self.name: write_value})
  File "/opt/odoo/addons/account/models/account_move.py", line 4889, in write
    to_write = line._get_price_total_and_subtotal()
  File "/mnt/data/odoo-addons-dir/account_invoice_triple_discount/models/account_move_line.py", line 73, in _get_price_total_and_subtotal
    return super(AccountMoveLine, self)._get_price_total_and_subtotal(**kwargs)
  File "/opt/odoo/addons/account/models/account_move.py", line 4078, in _get_price_total_and_subtotal
    return self._get_price_total_and_subtotal_model(
  File "/mnt/data/odoo-addons-dir/account_invoice_fixed_discount/models/account_move.py", line 74, in _get_price_total_and_subtotal_model
    discount = ((self.discount_fixed) / price_unit) * 100 or 0.00
Exception

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/opt/odoo/odoo/http.py", line 654, in _handle_exception
    return super(JsonRequest, self)._handle_exception(exception)
  File "/opt/odoo/odoo/http.py", line 301, in _handle_exception
    raise exception.with_traceback(None) from new_cause
ZeroDivisionError: float division by zero

To Reproduce

15.0

Steps to reproduce the behavior:
These are the steps I have followed in the OCA Runboat (Odoo 15.0):

1. Move a published invoice of at least one day difference to draft and remove the invoice date.

2. Set a fixed discount on a line so that the subtotal is 0.
   

3. Click on "Confirm" button.

Expected behavior
Invoice confirmed with no division by zero errors.

Additional context
Tested on runboat 15.0
http://oca-account-invoicing-15-0-1172046897ce.runboat.odoo-community.org/web?debug=1#id=3&cids=1&menu_id=143&action=258&model=account.move&view_type=form

The problem is when we try to confirm an invoice at least 1 day late, because if we create an invoice today and confirm it today, there is no problem.