From 14a1bb423c036a285f7570483fcb318910b2440f Mon Sep 17 00:00:00 2001
From: Erik Montnemery <erik@montnemery.com>
Date: Mon, 27 Sep 2021 10:47:57 +0200
Subject: [PATCH] Add is_number template filter and function (#56705)

---
 homeassistant/helpers/template.py | 13 ++++++++++++
 tests/helpers/test_template.py    | 35 +++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+)

diff --git a/homeassistant/helpers/template.py b/homeassistant/helpers/template.py
index 3580af3e2bd..94323c14f56 100644
--- a/homeassistant/helpers/template.py
+++ b/homeassistant/helpers/template.py
@@ -1370,6 +1370,17 @@ def forgiving_float(value):
         return value
 
 
+def is_number(value):
+    """Try to convert value to a float."""
+    try:
+        fvalue = float(value)
+    except (ValueError, TypeError):
+        return False
+    if math.isnan(fvalue) or math.isinf(fvalue):
+        return False
+    return True
+
+
 def regex_match(value, find="", ignorecase=False):
     """Match value using regex."""
     if not isinstance(value, str):
@@ -1575,6 +1586,7 @@ class TemplateEnvironment(ImmutableSandboxedEnvironment):
         self.filters["bitwise_and"] = bitwise_and
         self.filters["bitwise_or"] = bitwise_or
         self.filters["ord"] = ord
+        self.filters["is_number"] = is_number
         self.globals["log"] = logarithm
         self.globals["sin"] = sine
         self.globals["cos"] = cosine
@@ -1597,6 +1609,7 @@ class TemplateEnvironment(ImmutableSandboxedEnvironment):
         self.globals["urlencode"] = urlencode
         self.globals["max"] = max
         self.globals["min"] = min
+        self.globals["is_number"] = is_number
         self.tests["match"] = regex_match
         self.tests["search"] = regex_search
 
diff --git a/tests/helpers/test_template.py b/tests/helpers/test_template.py
index efdcebf70e1..0ac59c68d2d 100644
--- a/tests/helpers/test_template.py
+++ b/tests/helpers/test_template.py
@@ -220,6 +220,41 @@ def test_float(hass):
     )
 
 
+@pytest.mark.parametrize(
+    "value, expected",
+    [
+        (0, True),
+        (0.0, True),
+        ("0", True),
+        ("0.0", True),
+        (True, True),
+        (False, True),
+        ("True", False),
+        ("False", False),
+        (None, False),
+        ("None", False),
+        ("horse", False),
+        (math.pi, True),
+        (math.nan, False),
+        (math.inf, False),
+        ("nan", False),
+        ("inf", False),
+    ],
+)
+def test_isnumber(hass, value, expected):
+    """Test is_number."""
+    assert (
+        template.Template("{{ is_number(value) }}", hass).async_render({"value": value})
+        == expected
+    )
+    assert (
+        template.Template("{{ value | is_number }}", hass).async_render(
+            {"value": value}
+        )
+        == expected
+    )
+
+
 def test_rounding_value(hass):
     """Test rounding value."""
     hass.states.async_set("sensor.temperature", 12.78)