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Settings - case sensitivity - misleading example in docs #1105
Description
Bug
Please complete:
- OS: Linux
- Python version
import sys; print(sys.version): 3.6.9 - Pydantic version
import pydantic; print(pydantic.VERSION): 1.2
There is an example in docs about case sensitivity of environment variable names: https://pydantic-docs.helpmanual.io/usage/settings/#environment-variable-names.
I cite it here for convenience:
Case-sensitivity can be turned on through the Config:
from pydantic import BaseSettings
class Settings(BaseSettings):
redis_host = 'localhost'
class Config:
case_sensitive = TrueWhen
case_sensitiveisTrue, the environment variable must be in all-caps, so in this exampleredis_hostcould only be modified viaexport REDIS_HOST.
This example is simply incorrect. It leads that you can name Settings attrs using "snake_case", and export env variable named "UPPER_CASE", and Settings will catch them and populate proper attr with value taken from this env variable. This is not the case. In fact, if you want case sensitive environment variable names, you must name Settings attributes all "UPPER_CASE" as well.
Proof
Let's take this example "as is" and try to override settings attribute using environment variable:
import os
from pydantic import BaseSettings
class Settings(BaseSettings):
redis_host = 'localhost'
class Config:
case_sensitive = True
Settings().redis_host
'localhost' # default
os.environ['REDIS_HOST'] = 'myredis' # according to example, we must name env var all UPPER_CASE
Settings().redis_host
'localhost' # still default
os.environ['redis_host'] = 'myredis'
Settings().redis_host
'myredis' # now it's working
Activity
samuelcolvin commentedon Dec 18, 2019
Thank you for reporting this, I guess we forgot to update the documentation when the functionality changed.
PR welcome to correct the docs.
tribals commentedon Dec 18, 2019
I will submit PR, but just need to clarify current behavior/any drawbacks? Does it just turns case sensitivity on without any "smarty" logic? So, attribute names must match environment variable names closely?
samuelcolvin commentedon Dec 18, 2019
No, the other logic for working out environment variable names to look up is unchanged.
Just that if
not self.case_sensitiveeverything is converted to lowercase before the lookup.https://github.com/samuelcolvin/pydantic/blob/de6bd1b4694dc7b04c9626e39fd494965f230b7c/pydantic/env_settings.py#L67-L88
tribals commentedon Dec 18, 2019
But, if there is no explicit binding to environment variable (through
Field.env), then variable name is taken from attribute's name, and follow its case as is, is it correct?samuelcolvin commentedon Dec 18, 2019
well it's
cls.env_prefix + field.namebutenv_prefixis an empty list by default, so yes.Bump uuid from 1.5.0 to 1.6.1 (pydantic#1105)