[IMP] account_payment_order: Concatenate all UserError messages

Gather all the errors to only show one with all the problem on the current debit order. This will avoid for the users to have to make multiple time the same process.

account_payment_order/models/account_payment_order.py

@@ -292,9 +292,13 @@ class AccountPaymentOrder(models.Model):
             order.payment_ids.action_cancel()
             order.payment_ids.unlink()
             # Prepare account payments from the payment lines
+            payline_err_text = []
             group_paylines = {}  # key = hashcode
             for payline in order.payment_line_ids:
-                payline.draft2open_payment_line_check()
+                try:
+                    payline.draft2open_payment_line_check()
+                except UserError as e:
+                    payline_err_text.append(e.args[0])
                 # Compute requested payment date
                 if order.date_prefered == "due":
                     requested_date = payline.ml_maturity_date or payline.date or today
@@ -303,8 +307,7 @@ class AccountPaymentOrder(models.Model):
                 else:
                     requested_date = today
                 # No payment date in the past
-                if requested_date < today:
-                    requested_date = today
+                requested_date = max(today, requested_date)
                 # inbound: check option no_debit_before_maturity
                 if (
                     order.payment_type == "inbound"
@@ -312,7 +315,7 @@ class AccountPaymentOrder(models.Model):
                     and payline.ml_maturity_date
                     and requested_date < payline.ml_maturity_date
                 ):
-                    raise UserError(
+                    payline_err_text.append(
                         _(
                             "The payment mode '%(pmode)s' has the option "
                             "'Disallow Debit Before Maturity Date'. The "
@@ -332,11 +335,11 @@ class AccountPaymentOrder(models.Model):
                 with self.env.norecompute():
                     payline.date = requested_date
                 # Group options
-                if order.payment_mode_id.group_lines:
-                    hashcode = payline.payment_line_hashcode()
-                else:
-                    # Use line ID as hascode, which actually means no grouping
-                    hashcode = payline.id
+                hashcode = (
+                    payline.payment_line_hashcode()
+                    if order.payment_mode_id.group_lines
+                    else payline.id
+                )
                 if hashcode in group_paylines:
                     group_paylines[hashcode]["paylines"] += payline
                     group_paylines[hashcode]["total"] += payline.amount_currency
@@ -345,7 +348,15 @@ class AccountPaymentOrder(models.Model):
                         "paylines": payline,
                         "total": payline.amount_currency,
                     }
+            # Raise errors that happened on the validation process
+            if payline_err_text:
+                raise UserError(
+                    _("There's at least one validation error:\n")
+                    + "\n".join(payline_err_text)
+                )
+
             order.env.flush_all()
+
             # Create account payments
             payment_vals = []
             for paydict in list(group_paylines.values()):