add contexual field to invoice form and copy value from sales if available

sale_order_contextual/models/__init__.py

@@ -1 +1,2 @@
 from . import sale_order_contextual
+from . import account_move

sale_order_contextual/models/account_move.py

@@ -0,0 +1,9 @@
+from odoo import fields, models
+
+
+class AccountMoveContextual(models.Model):
+    _inherit = 'account.move'
+
+    contextual_note = fields.Text(
+        string='Contextuele opmerking',
+    )

sale_order_contextual/models/sale_order_contextual.py

@@ -7,3 +7,9 @@ class SaleOrderContextual(models.Model):
     contextual_note = fields.Text(
         string='Contextuele opmerking',
     )
+
+    def _prepare_invoice(self):
+        vals = super()._prepare_invoice()
+        if self.contextual_note:
+            vals['contextual_note'] = self.contextual_note
+        return vals