Added namedtuple with defaults compatible.

src/django_clickhouse/compatibility.py

@@ -0,0 +1,47 @@
+import sys
+from collections import namedtuple as basenamedtuple
+from functools import lru_cache
+
+from copy import deepcopy
+
+
+class NamedTuple:
+    __slots__ = ('_data', '_data_iterator')
+    _defaults = {}
+    _data_cls = None
+
+    @classmethod
+    @lru_cache(maxsize=32)
+    def _get_defaults(cls, exclude):
+        res = cls._defaults
+        for k in exclude:
+            res.pop(k, None)
+        return res
+
+    def __init__(self, *args, **kwargs):
+        new_kwargs = deepcopy(self._get_defaults(self._data_cls._fields[:len(args)]))
+        new_kwargs.update(kwargs)
+        self._data = self._data_cls(*args, **new_kwargs)
+
+    def __getattr__(self, item):
+        return getattr(self._data, item)
+
+    def __iter__(self):
+        self._data_iterator = iter(self._data)
+        return self
+
+    def __next__(self):
+        return next(self._data_iterator)
+
+
+def namedtuple(*args, **kwargs):
+    """
+    Changes namedtuple to support defaults parameter as python 3.7 does
+    https://docs.python.org/3.7/library/collections.html#collections.namedtuple
+    :return: namedtuple class
+    """
+    if sys.version_info < (3, 7):
+        defaults = kwargs.pop('defaults', {})
+        return type('namedtuple', (NamedTuple,), {'_defaults': defaults, '_data_cls': basenamedtuple(*args, **kwargs)})
+    else:
+        return basenamedtuple(*args, **kwargs)

tests/test_compatibility.py

@@ -0,0 +1,36 @@
+from unittest import TestCase
+
+from django_clickhouse.compatibility import namedtuple
+
+
+class NamedTupleTest(TestCase):
+    def test_defaults(self):
+        TestTuple = namedtuple('TestTuple', ('a', 'b', 'c'), defaults={'c': 3})
+        self.assertTupleEqual((1, 2, 3), tuple(TestTuple(1, b=2)))
+        self.assertTupleEqual((1, 2, 4), tuple(TestTuple(1, 2, 4)))
+        self.assertTupleEqual((1, 2, 4), tuple(TestTuple(a=1, b=2, c=4)))
+
+    def test_exceptions(self):
+        TestTuple = namedtuple('TestTuple', ('a', 'b', 'c'), defaults={'c': 3})
+        with self.assertRaises(TypeError):
+            TestTuple(b=1, c=4)
+
+        with self.assertRaises(TypeError):
+            TestTuple(1, 2, 3, c=4)
+
+    def test_different_defaults(self):
+        # Test that 2 tuple type defaults don't affect each other
+        TestTuple = namedtuple('TestTuple', ('a', 'b', 'c'), defaults={'c': 3})
+        OtherTuple = namedtuple('TestTuple', ('a', 'b', 'c'), defaults={'c': 4})
+        t1 = TestTuple(a=1, b=2)
+        t2 = OtherTuple(a=3, b=4)
+        self.assertTupleEqual((1, 2, 3), tuple(t1))
+        self.assertTupleEqual((3, 4, 4), tuple(t2))
+
+    def test_defaults_cache(self):
+        # Test that 2 tuple instances don't affect each other's defaults
+        TestTuple = namedtuple('TestTuple', ('a', 'b', 'c'), defaults={'c': 3})
+        self.assertTupleEqual((1, 2, 4), tuple(TestTuple(a=1, b=2, c=4)))
+        self.assertTupleEqual((1, 2, 3), tuple(TestTuple(a=1, b=2)))
+
+