Serialize NaN and Infinity values as strings for Hamilton UI

ui/sdk/src/hamilton_sdk/tracking/utils.py

@@ -58,11 +58,11 @@ def make_json_safe(item: Union[dict, list, str, float, int, bool]) -> Any:
         return make_json_safe(item.to_dict())
     else:
         try:
-            json.dumps(item)  # Check if item is json serializable
+            json.dumps(item, allow_nan=False)  # Check if item is json serializable
             if isinstance(item, str):
                 # escape null byte -- postgres doesn't like null bytes at least.
                 # we might need to escape more things; TBD.
                 return item.replace("\x00", "\\x00")
             return item
-        except TypeError:
+        except (TypeError, ValueError):
             return str(item)  # Convert item to string if not json serializable

ui/sdk/tests/tracking/test_utils.py

@@ -157,3 +157,28 @@ def test_make_json_safe_str_with_null_byte():
     assert isinstance(result, dict)
     assert isinstance(result["key2"], str)
     assert result["key2"] == "value\\x00"
+
+
+def test_make_json_safe_with_nan():
+    """Test that NaN and Infinity values are properly handled in make_json_safe"""
+    import math
+
+    # Test with a dictionary
+    input_dict = {"a": math.nan, "b": np.nan, "c": 1.0, "d": math.inf, "e": -math.inf}
+    result = utils.make_json_safe(input_dict)
+    assert isinstance(result, dict)
+    assert result["a"] == "nan"  # NaN should be represented as "nan"
+    assert result["b"] == "nan"  # …same for numpy.nan
+    assert result["c"] == 1.0  # Regular float should remain unchanged
+    assert result["d"] == "inf"  # Infinity should be represented as "inf"
+    assert result["e"] == "-inf"  # Negative infinity should be represented as "-inf"
+
+    # Test with a list
+    input_list = [math.nan, np.nan, 1.0, math.inf, -math.inf]
+    result = utils.make_json_safe(input_list)
+    assert isinstance(result, list)
+    assert result[0] == "nan"  # NaN should be represented as "nan"
+    assert result[1] == "nan"  # …same for numpy.nan
+    assert result[2] == 1.0  # Regular float should remain unchanged
+    assert result[3] == "inf"  # Infinity should be represented as "inf"
+    assert result[4] == "-inf"  # Negative infinity should be represented as "-inf"