feat(automation): add custom template filters

surfsense_backend/app/automations/templating/filters.py

@@ -0,0 +1,29 @@
+"""Custom Jinja filters registered into the sandboxed environment."""
+
+from __future__ import annotations
+
+import re
+from typing import Any
+
+
+def filter_date(value: Any, fmt: str = "%Y-%m-%d") -> str:
+    """Format a datetime-like value with ``strftime``. Strings pass through."""
+    if value is None:
+        return ""
+    if isinstance(value, str):
+        return value
+    if hasattr(value, "strftime"):
+        return value.strftime(fmt)
+    raise ValueError(f"date filter requires datetime-like, got {type(value).__name__}")
+
+
+_SLUG_NONALNUM = re.compile(r"[^a-z0-9]+")
+_SLUG_DASHES = re.compile(r"-+")
+
+
+def filter_slugify(value: Any) -> str:
+    """Lowercase, replace non-alphanumerics with hyphens, collapse and trim."""
+    s = str(value).lower()
+    s = _SLUG_NONALNUM.sub("-", s)
+    s = _SLUG_DASHES.sub("-", s)
+    return s.strip("-")