Use dateutil parser (#213)

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

poetry.lock

@@ -559,6 +559,17 @@ pytest = ">=5.0"
 [package.extras]
 dev = ["pre-commit", "tox", "pytest-asyncio"]
 
+[[package]]
+name = "python-dateutil"
+version = "2.8.1"
+description = "Extensions to the standard Python datetime module"
+category = "main"
+optional = false
+python-versions = "!=3.0.*,!=3.1.*,!=3.2.*,>=2.7"
+
+[package.dependencies]
+six = ">=1.5"
+
 [[package]]
 name = "pytz"
 version = "2020.5"
@@ -831,7 +842,7 @@ compiler = ["black", "jinja2", "protobuf"]
 [metadata]
 lock-version = "1.1"
 python-versions = "^3.6"
-content-hash = "a8e4b87ff691fd815c51637f7fd24606c9ccdfbb7d9466a01c844fdfc58922c0"
+content-hash = "5b967c5bfc330b1fa82efdebd8ce61c9d947ebe39c66ee1cd060f6aad45acba1"
 
 [metadata.files]
 alabaster = [
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 more-itertools = [
@@ -1302,6 +1332,10 @@ pytest-mock = [
     {file = "pytest-mock-3.5.1.tar.gz", hash = "sha256:a1e2aba6af9560d313c642dae7e00a2a12b022b80301d9d7fc8ec6858e1dd9fc"},
     {file = "pytest_mock-3.5.1-py3-none-any.whl", hash = "sha256:379b391cfad22422ea2e252bdfc008edd08509029bcde3c25b2c0bd741e0424e"},
 ]
+python-dateutil = [
+    {file = "python-dateutil-2.8.1.tar.gz", hash = "sha256:73ebfe9dbf22e832286dafa60473e4cd239f8592f699aa5adaf10050e6e1823c"},
+    {file = "python_dateutil-2.8.1-py2.py3-none-any.whl", hash = "sha256:75bb3f31ea686f1197762692a9ee6a7550b59fc6ca3a1f4b5d7e32fb98e2da2a"},
+]
 pytz = [
     {file = "pytz-2020.5-py2.py3-none-any.whl", hash = "sha256:16962c5fb8db4a8f63a26646d8886e9d769b6c511543557bc84e9569fb9a9cb4"},
     {file = "pytz-2020.5.tar.gz", hash = "sha256:180befebb1927b16f6b57101720075a984c019ac16b1b7575673bea42c6c3da5"},

pyproject.toml

@@ -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"

src/betterproto/__init__.py

@@ -8,6 +8,7 @@ import typing
 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 ._types import T
 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 @@ class Message(ABC):
                     if isinstance(v, list):
                         cls = self._betterproto.cls_by_field[field_name]
                         if cls == datetime:
-                            v = [
+                            v = [isoparse(item) for item in value[key]]
-                                datetime.fromisoformat(item.replace("Z", "+00:00"))
-                                for item in value[key]
-                            ]
                         elif cls == timedelta:
                             v = [
                                 timedelta(seconds=float(item[:-1]))
@@ -1063,7 +1055,7 @@ class Message(ABC):
                         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]))

tests/test_features.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 @@ def test_bool():
     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])