Use dateutil parser (#213)

Switch to using `isoparse` from `dateutil.parser` instead of `datetime.fromisoformat` for more robust parsing of dates in from_dict.

Author: robinaly

poetry.lock

@@ -13,12 +13,12 @@ packages = [
 
 [tool.poetry.dependencies]
 python = "^3.6"
-backports-datetime-fromisoformat = { version = "^1.0.0", python = "<3.7" }
 black = { version = ">=19.3b0", optional = true }
 dataclasses = { version = "^0.7", python = ">=3.6, <3.7" }
 grpclib = "^0.4.1"
 jinja2 = { version = "^2.11.2", optional = true }
 protobuf = { version = "^3.12.2", optional = true }
+python-dateutil = "^2.8"
 
 [tool.poetry.dev-dependencies]
 black = "^20.8b1"

pyproject.toml

@@ -8,6 +8,7 @@
 from abc import ABC
 from base64 import b64decode, b64encode
 from datetime import datetime, timedelta, timezone
+from dateutil.parser import isoparse
 from typing import (
     Any,
     Callable,
@@ -26,12 +27,6 @@
 from .casing import camel_case, safe_snake_case, snake_case
 from .grpc.grpclib_client import ServiceStub
 
-if sys.version_info[:2] < (3, 7):
-    # Apply backport of datetime.fromisoformat from 3.7
-    from backports.datetime_fromisoformat import MonkeyPatch
-
-    MonkeyPatch.patch_fromisoformat()
-
 
 # Proto 3 data types
 TYPE_ENUM = "enum"
@@ -1051,10 +1046,7 @@ def from_dict(self: T, value: Dict[str, Any]) -> T:
                     if isinstance(v, list):
                         cls = self._betterproto.cls_by_field[field_name]
                         if cls == datetime:
-                            v = [
-                                datetime.fromisoformat(item.replace("Z", "+00:00"))
-                                for item in value[key]
-                            ]
+                            v = [isoparse(item) for item in value[key]]
                         elif cls == timedelta:
                             v = [
                                 timedelta(seconds=float(item[:-1]))
@@ -1063,7 +1055,7 @@ def from_dict(self: T, value: Dict[str, Any]) -> T:
                         else:
                             v = [cls().from_dict(item) for item in value[key]]
                     elif isinstance(v, datetime):
-                        v = datetime.fromisoformat(value[key].replace("Z", "+00:00"))
+                        v = isoparse(value[key])
                         setattr(self, field_name, v)
                     elif isinstance(v, timedelta):
                         v = timedelta(seconds=float(value[key][:-1]))

src/betterproto/__init__.py

@@ -1,6 +1,7 @@
 import betterproto
 from dataclasses import dataclass
 from typing import Optional, List, Dict
+from datetime import datetime, timedelta
 
 
 def test_has_field():
@@ -395,3 +396,70 @@ class Truthy(betterproto.Message):
     assert t
     t.bar = 0
     assert not t
+
+
+# valid ISO datetimes according to https://www.myintervals.com/blog/2009/05/20/iso-8601-date-validation-that-doesnt-suck/
+iso_candidates = """2009-12-12T12:34
+2009
+2009-05-19
+2009-05-19
+20090519
+2009123
+2009-05
+2009-123
+2009-222
+2009-001
+2009-W01-1
+2009-W51-1
+2009-W33
+2009W511
+2009-05-19
+2009-05-19 00:00
+2009-05-19 14
+2009-05-19 14:31
+2009-05-19 14:39:22
+2009-05-19T14:39Z
+2009-W21-2
+2009-W21-2T01:22
+2009-139
+2009-05-19 14:39:22-06:00
+2009-05-19 14:39:22+0600
+2009-05-19 14:39:22-01
+20090621T0545Z
+2007-04-06T00:00
+2007-04-05T24:00
+2010-02-18T16:23:48.5
+2010-02-18T16:23:48,444
+2010-02-18T16:23:48,3-06:00
+2010-02-18T16:23:00.4
+2010-02-18T16:23:00,25
+2010-02-18T16:23:00.33+0600
+2010-02-18T16:00:00.23334444
+2010-02-18T16:00:00,2283
+2009-05-19 143922
+2009-05-19 1439""".split(
+    "\n"
+)
+
+
+def test_iso_datetime():
+    @dataclass
+    class Envelope(betterproto.Message):
+        ts: datetime = betterproto.message_field(1)
+
+    msg = Envelope()
+
+    for _, candidate in enumerate(iso_candidates):
+        msg.from_dict({"ts": candidate})
+        assert isinstance(msg.ts, datetime)
+
+
+def test_iso_datetime_list():
+    @dataclass
+    class Envelope(betterproto.Message):
+        timestamps: List[datetime] = betterproto.message_field(1)
+
+    msg = Envelope()
+
+    msg.from_dict({"timestamps": iso_candidates})
+    assert all([isinstance(item, datetime) for item in msg.timestamps])