Added the UnappliedAccountConverter path converter to only allow the accounts that need offsets.

src/accounting/report/__init__.py

@@ -27,9 +27,11 @@ def init_app(app: Flask, url_prefix: str) -> None:
     :param url_prefix: The URL prefix of the accounting application.
     :return: None.
     """
-    from .converters import PeriodConverter, CurrentAccountConverter
+    from .converters import PeriodConverter, CurrentAccountConverter, \
+        UnappliedAccountConverter
     app.url_map.converters["period"] = PeriodConverter
     app.url_map.converters["currentAccount"] = CurrentAccountConverter
+    app.url_map.converters["unappliedAccount"] = UnappliedAccountConverter
 
     from .views import bp as report_bp
     app.register_blueprint(report_bp, url_prefix=url_prefix)

src/accounting/report/converters.py

@@ -77,3 +77,29 @@ class CurrentAccountConverter(BaseConverter):
         :return: Its code.
         """
         return value.code
+
+
+class UnappliedAccountConverter(BaseConverter):
+    """The converter to convert the unapplied original line item account code
+    from and to the corresponding account in the routes."""
+
+    def to_python(self, value: str) -> Account:
+        """Converts an account code to an account.
+
+        :param value: The account code.
+        :return: The corresponding account.
+        """
+        account: Account | None = Account.find_by_code(value)
+        if account is None:
+            abort(404)
+        if not account.is_need_offset:
+            abort(404)
+        return account
+
+    def to_url(self, value: Account) -> str:
+        """Converts an account to account code.
+
+        :param value: The account.
+        :return: Its code.
+        """
+        return value.code

src/accounting/report/views.py

@@ -286,7 +286,7 @@ def __get_balance_sheet(currency: Currency, period: Period) \
     return report.html()
 
 
-@bp.get("unapplied/<account:account>", endpoint="unapplied")
+@bp.get("unapplied/<unappliedAccount:account>", endpoint="unapplied")
 @has_permission(can_view)
 def get_unapplied(account: Account) -> str | Response:
     """Returns the unapplied original line items.