Prevent deletion of payment terms in use

Closes #12085

modules/account_invoice/invoice.py

@@ -169,8 +169,9 @@ class Invoice(Workflow, ModelSQL, ModelView, TaxableMixin):
                 Eval('accounting_date'),
                 Eval('invoice_date')),
             })
-    payment_term = fields.Many2One('account.invoice.payment_term',
-        'Payment Term', states=_states)
+    payment_term = fields.Many2One(
+        'account.invoice.payment_term', "Payment Term",
+        ondelete='RESTRICT', states=_states)
     alternative_payees = fields.Many2Many(
         'account.invoice.alternative_payee', 'invoice', 'party',
         "Alternative Payee", states=_states,

modules/purchase/purchase.py

@@ -92,8 +92,9 @@ class Purchase(
             'required': ~Eval('state').in_(
                 ['draft', 'quotation', 'cancelled']),
             })
-    payment_term = fields.Many2One('account.invoice.payment_term',
-        'Payment Term', states={
+    payment_term = fields.Many2One(
+        'account.invoice.payment_term', "Payment Term", ondelete='RESTRICT',
+        states={
             'readonly': ~Eval('state').in_(['draft', 'quotation']),
             })
     party = fields.Many2One('party.party', 'Party', required=True,

modules/purchase_amendment/purchase.py

@@ -196,7 +196,7 @@ class AmendmentLine(ModelSQL, ModelView):
             })
 
     payment_term = fields.Many2One(
-        'account.invoice.payment_term', "Payment Term",
+        'account.invoice.payment_term', "Payment Term", ondelete='RESTRICT',
         states={
             'invisible': Eval('action') != 'payment_term',
             })

modules/sale/sale.py

@@ -89,8 +89,8 @@ class Sale(
             'required': ~Eval('state').in_(
                 ['draft', 'quotation', 'cancelled']),
             })
-    payment_term = fields.Many2One('account.invoice.payment_term',
-        'Payment Term',
+    payment_term = fields.Many2One(
+        'account.invoice.payment_term', "Payment Term", ondelete='RESTRICT',
         states={
             'readonly': Eval('state') != 'draft',
             })

modules/sale_amendment/sale.py

@@ -212,7 +212,7 @@ class AmendmentLine(ModelSQL, ModelView):
             })
 
     payment_term = fields.Many2One(
-        'account.invoice.payment_term', "Payment Term",
+        'account.invoice.payment_term', "Payment Term", ondelete='RESTRICT',
         states={
             'invisible': Eval('action') != 'payment_term',
             })

modules/sale_opportunity/opportunity.py

@@ -75,8 +75,9 @@ class SaleOpportunity(
         "Amount", currency='currency', digits='currency',
         states=_states_stop,
         help='Estimated revenue amount.')
-    payment_term = fields.Many2One('account.invoice.payment_term',
-        'Payment Term', states={
+    payment_term = fields.Many2One(
+        'account.invoice.payment_term', "Payment Term", ondelete='RESTRICT',
+        states={
             'readonly': In(Eval('state'),
                 ['converted', 'lost', 'cancelled']),
             })

modules/sale_subscription/subscription.py

@@ -92,7 +92,7 @@ class Subscription(Workflow, ModelSQL, ModelView):
             'required': ~Eval('state').in_(['draft']),
             })
     payment_term = fields.Many2One(
-        'account.invoice.payment_term', "Payment Term",
+        'account.invoice.payment_term', "Payment Term", ondelete='RESTRICT',
         states={
             'readonly': Eval('state') != 'draft',
             })