Add from_hex filter (#145229)

homeassistant/helpers/template.py

@@ -2572,6 +2572,11 @@ def struct_unpack(value: bytes, format_string: str, offset: int = 0) -> Any | No
         return None
 
 
+def from_hex(value: str) -> bytes:
+    """Perform hex string decode."""
+    return bytes.fromhex(value)
+
+
 def base64_encode(value: str) -> str:
     """Perform base64 encode."""
     return base64.b64encode(value.encode("utf-8")).decode("utf-8")
@@ -3131,6 +3136,7 @@ class TemplateEnvironment(ImmutableSandboxedEnvironment):
         self.filters["flatten"] = flatten
         self.filters["float"] = forgiving_float_filter
         self.filters["from_json"] = from_json
+        self.filters["from_hex"] = from_hex
         self.filters["iif"] = iif
         self.filters["int"] = forgiving_int_filter
         self.filters["intersect"] = intersect

tests/helpers/test_template.py

@@ -1632,6 +1632,14 @@ def test_ord(hass: HomeAssistant) -> None:
     assert template.Template('{{ "d" | ord }}', hass).async_render() == 100
 
 
+def test_from_hex(hass: HomeAssistant) -> None:
+    """Test the fromhex filter."""
+    assert (
+        template.Template("{{ '0F010003' | from_hex }}", hass).async_render()
+        == b"\x0f\x01\x00\x03"
+    )
+
+
 def test_base64_encode(hass: HomeAssistant) -> None:
     """Test the base64_encode filter."""
     assert (