fix: duplicate leave expiry creation (#21506)

* fix: validate existing ledger entries to avoid duplicates

* patch: remove duplicate ledger entries created

* fix: consider only submitted ledger entries

* fix: delete duplicate leaves from the ledger

* fix: check if duplicate ledger entry exists

* chore: formatting changes

Co-authored-by: Nabin Hait <nabinhait@gmail.com>

erpnext/patches/v12_0/remove_duplicate_leave_ledger_entries.py

@@ -0,0 +1,44 @@
+# Copyright (c) 2018, Frappe and Contributors
+# License: GNU General Public License v3. See license.txt
+
+from __future__ import unicode_literals
+import frappe
+
+def execute():
+	"""Delete duplicate leave ledger entries of type allocation created."""
+	if not frappe.db.a_row_exists("Leave Ledger Entry"):
+		return
+
+	duplicate_records_list = get_duplicate_records()
+	delete_duplicate_ledger_entries(duplicate_records_list)
+
+def get_duplicate_records():
+	"""Fetch all but one duplicate records from the list of expired leave allocation."""
+	return frappe.db.sql_list("""
+		WITH duplicate_records AS
+		(SELECT
+			name, transaction_name, is_carry_forward,
+			ROW_NUMBER() over(partition by transaction_name order by creation)as row
+		FROM `tabLeave Ledger Entry` l
+		WHERE (EXISTS
+			(SELECT name
+				FROM `tabLeave Ledger Entry`
+				WHERE
+					transaction_name = l.transaction_name
+					AND transaction_type = 'Leave Allocation'
+					AND name <> l.name
+					AND employee = l.employee
+					AND docstatus = 1
+					AND leave_type = l.leave_type
+					AND is_carry_forward=l.is_carry_forward
+					AND to_date = l.to_date
+					AND from_date = l.from_date
+					AND is_expired = 1
+		)))
+		SELECT name FROM duplicate_records WHERE row > 1
+	""")
+
+def delete_duplicate_ledger_entries(duplicate_records_list):
+	"""Delete duplicate leave ledger entries."""
+	if duplicate_records_list:
+		frappe.db.sql(''' DELETE FROM `tabLeave Ledger Entry` WHERE name in {0}'''.format(tuple(duplicate_records_list))) #nosec