From fa1212f2dee216bd02b321e3747c22fc854b31a5 Mon Sep 17 00:00:00 2001
From: moson <moson@archlinux.org>
Date: Mon, 10 Jul 2023 18:02:20 +0200
Subject: [PATCH] fix: translations not containing string formatting

In some translations we might be missing replacement placeholders (%).
This turns out to be problematic when calling the format function.

Wrap the jinja2 format function and just return the string unformatted
when % is missing.

Fixes: #341
Signed-off-by: moson <moson@archlinux.org>
---
 aurweb/filters.py    | 15 +++++++++++++++
 test/test_filters.py | 17 +++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/aurweb/filters.py b/aurweb/filters.py
index 893f21af..38322cdf 100644
--- a/aurweb/filters.py
+++ b/aurweb/filters.py
@@ -8,6 +8,7 @@ from zoneinfo import ZoneInfo
 import fastapi
 import paginate
 from jinja2 import pass_context
+from jinja2.filters import do_format
 
 import aurweb.models
 from aurweb import config, l10n
@@ -164,3 +165,17 @@ def date_display(context: dict[str, Any], dt: Union[int, datetime]) -> str:
 @pass_context
 def datetime_display(context: dict[str, Any], dt: Union[int, datetime]) -> str:
     return date_strftime(context, dt, "%Y-%m-%d %H:%M (%Z)")
+
+
+@register_filter("format")
+def safe_format(value: str, *args: Any, **kwargs: Any) -> str:
+    """Wrapper for jinja2 format function to perform additional checks."""
+
+    # If we don't have anything to be formatted, just return the value.
+    # We have some translations that do not contain placeholders for replacement.
+    # In these cases the jinja2 function is throwing an error:
+    # "TypeError: not all arguments converted during string formatting"
+    if "%" not in value:
+        return value
+
+    return do_format(value, *args, **kwargs)
diff --git a/test/test_filters.py b/test/test_filters.py
index e74ddb87..b56b80ab 100644
--- a/test/test_filters.py
+++ b/test/test_filters.py
@@ -1,6 +1,8 @@
 from datetime import datetime
 from zoneinfo import ZoneInfo
 
+import pytest
+
 from aurweb import filters, time
 
 
@@ -34,3 +36,18 @@ def test_to_qs():
     query = {"a": "b", "c": [1, 2, 3]}
     qs = filters.to_qs(query)
     assert qs == "a=b&c=1&c=2&c=3"
+
+
+@pytest.mark.parametrize(
+    "value, args, expected",
+    [
+        ("", (), ""),
+        ("a", (), "a"),
+        ("a", (1,), "a"),
+        ("%s", ("a",), "a"),
+        ("%s", ("ab",), "ab"),
+        ("%s%d", ("a", 1), "a1"),
+    ],
+)
+def test_safe_format(value: str, args: tuple, expected: str):
+    assert filters.safe_format(value, *args) == expected