Serialize all NumPy integer, float and bool scalars in json_serial

pygeoapi/util.py

@@ -426,10 +426,12 @@ def json_serial(obj: Any) -> str:
             return base64.b64encode(obj)
     elif isinstance(obj, Decimal):
         return float(obj)
-    elif type(obj).__name__ in ['int32', 'int64']:
+    elif _is_numpy_scalar(obj, 'integer'):
         return int(obj)
-    elif type(obj).__name__ in ['float32', 'float64']:
+    elif _is_numpy_scalar(obj, 'floating'):
         return float(obj)
+    elif _is_numpy_scalar(obj, 'bool', 'bool_'):
+        return bool(obj)
     elif isinstance(obj, l10n.Locale):
         return l10n.locale2str(obj)
     elif isinstance(obj, (pathlib.PurePath, Path)):
@@ -442,6 +444,22 @@ def json_serial(obj: Any) -> str:
         raise TypeError(msg)
 
 
+def _is_numpy_scalar(obj: Any, *type_names: str) -> bool:
+    """
+    helper function to check whether an object is a NumPy scalar of
+    a given abstract type (e.g. `integer` covers `int8` to `uint64`),
+    without requiring NumPy to be installed
+
+    :param obj: `object` to be evaluated
+    :param type_names: NumPy type names to match
+
+    :returns: `bool` of whether the object is a matching NumPy scalar
+    """
+
+    return any(cls.__module__ == 'numpy' and cls.__name__ in type_names
+               for cls in type(obj).__mro__)
+
+
 def is_url(urlstring: str) -> bool:
     """
     Validation function that determines whether a candidate URL should be

tests/other/test_util.py

@@ -31,10 +31,12 @@
 from decimal import Decimal
 from copy import deepcopy
 from io import StringIO
+import json
 from unittest import mock
 import uuid
 from xml.sax.saxutils import unescape
 
+import numpy as np
 import pytest
 
 from pygeoapi import util
@@ -367,3 +369,24 @@ def test_format_datetime(value, format_, result):
 ])
 def test_format_duration(start, end, result):
     assert util.format_duration(start, end) == result
+
+
+@pytest.mark.parametrize('value,expected', [
+    (np.int8(-3), -3),
+    (np.int16(7), 7),
+    (np.int32(7), 7),
+    (np.int64(7), 7),
+    (np.uint8(255), 255),
+    (np.uint64(2**64 - 1), 2**64 - 1),
+    (np.float16(0.5), 0.5),
+    (np.float32(0.5), 0.5),
+    (np.float64(0.5), 0.5),
+    (np.bool_(True), True),
+])
+def test_json_serial_numpy_scalars(value, expected):
+    result = util.json_serial(value)
+    assert result == expected
+    assert type(result) is type(expected)
+    assert json.loads(json.dumps({'value': value},
+                                 default=util.json_serial)) == {
+        'value': expected}