mitsuse / typedjson-python Goto Github PK

In python static typing, integers are defined as being a subset of floats. In other words, you can do the following and it will not fail a Mypy check:

bar:float = 1.0 #Define bar as a float
bar = 1 #Assign an integer

I believe it is therefore natural to expect a json string given as an integer to not fail to be parsed into a class where the variable has been defined as a float. Take for example the following dataclass that has a single float variable defined:

@dataclass
class FloatVariable():
    var:float = 1.0

Trying to decode the following json string will fail with <DecodingError reason=<TypeMismatch path=('var',)>>:

{
  "var": 1
}

The reason I bring this up is that I have users who will be editing json-files which gets loaded into dataclasses in exactly this manner. There are variables which are defined as floats in the dataclasses, but users are very likely to write them as integers in the json files. It is unreasonable to demand from the users that they never define variables as integers in the json files. After all, there is no difference between 1 and 1.0 from the users perspective.

@mitsuse, the decode function (from typedjson/decoding.py) does not save the result.path variable when result is an instance of DecodingError. I don't think this is intended since this produces the following issue. Consider for example this call:

print(typedjson.decode(Tuple[int,int], (1,'2')))

Right now this produces DecodingError(()) while I suppose it should produce DecodingError(('1',)). I think that we should check if the result.path variable was changed and in that case update the path parameter like so:

for d in decoders:
   result = d(type_, json, path)
   if not isinstance(result, DecodingError):
      break
   elif result.path:
      path = result.path

I'm getting this error when running a python azure function that uses typedjson package on Python 3.7 and 3.8.
Apparently the exception is caused by the dependency to dataclasses = "^0.6.0" in python >= 3.7.

See this issue:
#konradhalas/dacite#48
#google/flax#269

This is a proposed fix:
#konradhalas/dacite#49
#DataBiosphere/hca-metadata-api@8357cf0

Here is the entire stack trace:
Result: Failure Exception: AttributeError: module 'typing' has no attribute '_ClassVar' Stack: File "/azure-functions-host/workers/python/3.8/LINUX/X64/azure_functions_worker/dispatcher.py", line 262, in _handle__function_load_request func = loader.load_function( File "/azure-functions-host/workers/python/3.8/LINUX/X64/azure_functions_worker/utils/wrappers.py", line 32, in call return func(*args, **kwargs) File "/azure-functions-host/workers/python/3.8/LINUX/X64/azure_functions_worker/loader.py", line 76, in load_function mod = importlib.import_module(fullmodname) File "/usr/local/lib/python3.8/importlib/init.py", line 127, in import_module return _bootstrap._gcd_import(name[level:], package, level) File "", line 1014, in _gcd_import File "", line 991, in _find_and_load File "", line 975, in _find_and_load_unlocked File "", line 671, in _load_unlocked File "", line 783, in exec_module File "", line 219, in _call_with_frames_removed File "/home/site/wwwroot/TelraamScheduler/main.py", line 13, in from ..Common.Telraam.scrape_segment_message import ScrapeSegmentMessage File "/home/site/wwwroot/Common/Telraam/scrape_segment_message.py", line 5, in class ScrapeSegmentMessage(): File "/home/site/wwwroot/.python_packages/lib/site-packages/dataclasses.py", line 958, in dataclass return wrap(_cls) File "/home/site/wwwroot/.python_packages/lib/site-packages/dataclasses.py", line 950, in wrap return _process_class(cls, init, repr, eq, order, unsafe_hash, frozen) File "/home/site/wwwroot/.python_packages/lib/site-packages/dataclasses.py", line 800, in _process_class cls_fields = [_get_field(cls, name, type) File "/home/site/wwwroot/.python_packages/lib/site-packages/dataclasses.py", line 800, in cls_fields = [_get_field(cls, name, type) File "/home/site/wwwroot/.python_packages/lib/site-packages/dataclasses.py", line 659, in _get_field if (_is_classvar(a_type, typing) File "/home/site/wwwroot/.python_packages/lib/site-packages/dataclasses.py", line 550, in _is_classvar return type(a_type) is typing._ClassVar

Here are the dependecies log installed on azure:
2020-07-29T12:31:36.1317512Z ##[section]Starting: Install dependencies
2020-07-29T12:31:36.1324393Z ==============================================================================
2020-07-29T12:31:36.1324711Z Task : Bash
2020-07-29T12:31:36.1324987Z Description : Run a Bash script on macOS, Linux, or Windows
2020-07-29T12:31:36.1325234Z Version : 3.171.1
2020-07-29T12:31:36.1325456Z Author : Microsoft Corporation
2020-07-29T12:31:36.1325787Z Help : https://docs.microsoft.com/azure/devops/pipelines/tasks/utility/bash
2020-07-29T12:31:36.1326148Z ==============================================================================
2020-07-29T12:31:36.2840459Z Generating script.
2020-07-29T12:31:36.2872017Z ========================== Starting Command Output ===========================
2020-07-29T12:31:36.2889718Z [command]/bin/bash --noprofile --norc /home/vsts/work/_temp/d2b8fe8f-7b7e-4b41-8ec8-a516d419af47.sh
2020-07-29T12:31:42.4588411Z Looking in indexes:
2020-07-29T12:31:42.4590870Z Requirement already satisfied: setuptools in ./worker_venv/lib/python3.8/site-packages (41.2.0)
2020-07-29T12:31:42.8960266Z WARNING: You are using pip version 19.2.3, however version 20.2 is available.
2020-07-29T12:31:42.8962114Z You should consider upgrading via the 'pip install --upgrade pip' command.
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2020-07-29T12:31:48.8745190Z Downloading https://files.pythonhosted.org/packages/69/08/a0dcde53f9203fa83111e28fc368404c818a8c54c077ae66559b237c9dd4/azure_storage_queue-2.1.0-py2.py3-none-any.whl
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2020-07-29T12:31:58.1173912Z Downloading https://files.pythonhosted.org/packages/22/cd/a6aa959dca619918ccb55023b4cb151949c64d4d5d55b3f4ffd7eee0c6e8/docutils-0.15.2-py3-none-any.whl (547kB)
2020-07-29T12:31:58.3191857Z Installing collected packages: azure-functions, certifi, idna, chardet, urllib3, requests, oauthlib, requests-oauthlib, six, isodate, msrest, pycparser, cffi, cryptography, azure-core, azure-storage-blob, iso3166, uritemplate, polyline, python-dateutil, msgpack, cachecontrol, docutils, jmespath, botocore, s3transfer, boto3, mapbox, geographiclib, numpy, pytz, pandas, protobuf, capacity-ai-datadefinitions, openlocationcode, azure-common, azure-storage-common, azure-storage-queue, dataclasses, typing-extensions, typedjson, freezegun
2020-07-29T12:32:07.2638344Z Running setup.py install for openlocationcode: started
2020-07-29T12:32:07.5971977Z Running setup.py install for openlocationcode: finished with status 'done'
2020-07-29T12:32:07.7348544Z Successfully installed azure-common-1.1.25 azure-core-1.7.0 azure-functions-1.3.0 azure-storage-blob-12.3.2 azure-storage-common-2.1.0 azure-storage-queue-2.1.0 boto3-1.14.30 botocore-1.17.30 cachecontrol-0.12.6 capacity-ai-datadefinitions-0.0.36 certifi-2020.6.20 cffi-1.14.1 chardet-3.0.4 cryptography-3.0 dataclasses-0.6 docutils-0.15.2 freezegun-0.3.15 geographiclib-1.50 idna-2.10 iso3166-1.0.1 isodate-0.6.0 jmespath-0.10.0 mapbox-0.18.0 msgpack-1.0.0 msrest-0.6.18 numpy-1.19.1 oauthlib-3.1.0 openlocationcode-1.0.1 pandas-1.1.0 polyline-1.4.0 protobuf-3.12.2 pycparser-2.20 python-dateutil-2.8.1 pytz-2020.1 requests-2.24.0 requests-oauthlib-1.3.0 s3transfer-0.3.3 six-1.15.0 typedjson-0.7.5 typing-extensions-3.7.4.2 uritemplate-3.0.1 urllib3-1.25.10
2020-07-29T12:32:07.9797064Z WARNING: You are using pip version 19.2.3, however version 20.2 is available.
2020-07-29T12:32:07.9798382Z You should consider upgrading via the 'pip install --upgrade pip' command.
2020-07-29T12:32:08.0404274Z
2020-07-29T12:32:08.0468437Z ##[section]Finishing: Install dependencies

Hi, thank you for providing a great package!
I found that when we try to decode None as List[str], typedjson.decode() raises a runtime error. I think this behavior is unexpected and typedjson.decode() should return either the TypeMismatch error or the decoded result with an empty list.

$ cat example.py
from typing import List
import typedjson

json = None
print(typedjson.decode(List[str], json))

$ poetry run python example.py
Traceback (most recent call last):
  File "example.py", line 5, in <module>
    print(typedjson.decode(List[str], json))
  File "/Users/ny/local/src/github.com/mitsuse/typedjson-python/typedjson/decoding.py", line 90, in decode
    result = d(type_, json, path)
  File "/Users/ny/local/src/github.com/mitsuse/typedjson-python/typedjson/decoding.py", line 225, in decode_as_list
    for index, element in enumerate(json):
TypeError: 'NoneType' object is not iterable

This behavior can be problematic in situations such as the following: if we are expecting some list and no key for that list is given.

@dataclass(frozen=True)
class Person:
    name: str
    skills: List[str]

data = {'name': 'Taro', 'skill': ['C', 'Python']}  # the key specification of the received input has a typo.
person = typedjson.decode(Person, data)  # raises a runtime error!