Fix: 修复 dotenv 配置项为 None 将会跳过赋值

[eya46]

感觉是bug #2142

[codecov]

Codecov Report

Merging #2143 (7fc1d13) into master (c40b95f) will decrease coverage by 0.03%.
The diff coverage is 87.50%.

@@            Coverage Diff             @@
##           master    #2143      +/-   ##
==========================================
- Coverage   89.73%   89.70%   -0.03%     
==========================================
  Files          46       46              
  Lines        3340     3343       +3     
==========================================
+ Hits         2997     2999       +2     
- Misses        343      344       +1     

Flag	Coverage Δ
unittests	89.70% <87.50%> (-0.03%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
nonebot/config.py	93.68% <87.50%> (-0.89%)	⬇️

[github-actions]

🚀 Deployed on https://deploy-preview-2143--nonebot2.netlify.app

[yanyongyu]

应该替换这两行的默认值为 pydantic.fields.Undefined 然后下面改为is not undefined

nonebot2/nonebot/config.py

Lines 47 to 49 in 3bee189

	env_val: Optional[str] = None
	for env_name in field.field_info.extra["env_names"]:
	env_val = env_vars.get(env_name)

[eya46]

应该替换这两行的默认值为 pydantic.fields.Undefined 然后下面改为is not undefined

nonebot2/nonebot/config.py

Lines 47 to 49 in 3bee189

	env_val: Optional[str] = None
	for env_name in field.field_info.extra["env_names"]:
	env_val = env_vars.get(env_name)

env_val: Optional[str] = Undefined #46
for env_name in field.field_info.extra["env_names"]: #47
    env_val = env_vars.get(env_name) #48
# ...
if is_complex:
    # ...
elif env_val is not Undefined:
    d[field.alias] = env_val

这样改好像会导致pydantic报错

  File "pydantic\env_settings.py", line 39, in pydantic.env_settings.BaseSettings.__init__
  File "pydantic\main.py", line 341, in pydantic.main.BaseModel.__init__
pydantic.error_wrappers.ValidationError: 3 validation errors for Config
  driver
none is not an allowed value (type=type_error.none.not_allowed)
  host
none is not an allowed value (type=type_error.none.not_allowed)
  session_expire_timeout
none is not an allowed value (type=type_error.none.not_allowed)

[yanyongyu]

49行get的默认值呢？