refactor: disallow bank transactions on different currencies
diff --git a/erpnext/accounts/doctype/bank_transaction/bank_transaction.py b/erpnext/accounts/doctype/bank_transaction/bank_transaction.py
index 1d6cb8e..a049d40 100644
--- a/erpnext/accounts/doctype/bank_transaction/bank_transaction.py
+++ b/erpnext/accounts/doctype/bank_transaction/bank_transaction.py
@@ -48,6 +48,22 @@
 
 	def validate(self):
 		self.validate_duplicate_references()
+		self.validate_currency()
+
+	def validate_currency(self):
+		"""
+		Bank Transaction should be on the same currency as the Bank Account.
+		"""
+		if self.currency and self.bank_account:
+			account = frappe.get_cached_value("Bank Account", self.bank_account, "account")
+			account_currency = frappe.get_cached_value("Account", account, "account_currency")
+
+			if self.currency != account_currency:
+				frappe.throw(
+					_("Currency {0} cannot be different from Bank Account({1}) Currency: {2}").format(
+						frappe.bold(self.currency), frappe.bold(self.bank_account), frappe.bold(account_currency)
+					)
+				)
 
 	def set_status(self):
 		if self.docstatus == 2: