[FIX] Invoice cost center readonly if not draft

account_cost_center/models/account_invoice.py

@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-# Copyright 2015-2018 Onestein (<http://www.onestein.eu>)
+# Copyright 2015-2019 Onestein (<http://www.onestein.eu>)
 # License AGPL-3.0 or later (https://www.gnu.org/licenses/agpl).
 
 from odoo import api, fields, models
@@ -11,7 +11,9 @@ class AccountInvoice(models.Model):
     cost_center_id = fields.Many2one(
         'account.cost.center',
         string='Cost Center',
-        help='Default Cost Center'
+        readonly=True,
+        states={'draft': [('readonly', False)]},
+        help='Default Cost Center',
     )
 
     @api.model