[IMP]account_ux:prevent currency change when the invoice is not draft

closes #341

Ticket: 51808
Related: ingadhoc/odoo-argentina#615
Signed-off-by: Katherine Zaoral <kz@adhoc.com.ar>

account_ux/wizards/account_change_currency.py

@@ -3,6 +3,7 @@
 # directory
 ##############################################################################
 from odoo import fields, models, api, _
+from odoo.exceptions import ValidationError
 
 
 class AccountChangeCurrency(models.TransientModel):
@@ -55,6 +56,13 @@ def onchange_currency(self):
                 date=self.move_id.date or
                 fields.Date.context_today(self))
 
+    @api.constrains('currency_to_id', 'currency_rate')
+    def _prevent_change_currency(self):
+        """prevent currency or currency rate change when the invoice is not draft
+        """
+        if self.move_id.state != 'draft':
+            raise ValidationError(_('This invoice is not draft, reset it to draft to change currency or currency rate'))
+
     def change_currency(self):
         self.ensure_one()
         if self.change_type == 'currency':