Change BaseSettings defaults

[samuelcolvin]

So, to do before version 1:

I would like to see these two BaseSettings Config fields default to the following:

class Settings(BaseSettings):

  class Config:
    env_prefix = ""
    case_insensitive = True

Originally posted by @jasonkuhrt in #576 (comment)

[samuelcolvin]

I definitely agree about case_insensitive, not so sure about env_prefix, but I guess you're probably right.

[samuelcolvin]

I've got extremely frustrated with aliases in BaseSettings a number of times:

• they don't work well with inheritance
• you very often want to look for more than one alias, eg. here I have redis 'redis_settings': 'REDISCLOUD_URL' so aiohttp-toolbox works "out of the box" (no pun intended) on heroku with the redis cloud plugin I regularly use, but it's a slightly mad default. It would be much better if I could set multiple env varibles to inspect {'REDISCLOUD_URL', 'REDIS_URL'} or whatever.
• aliases are weird when initialising normally using arguments (eg. for testing) when you don't want to look for env variables, eg. I'd expect to do Settings(pg_dsn='postgres://postgres@localhost:5432/test_db') not have to respect the env var name and do Settings(DATABASE_URL='postgres://postgres@localhost:5432/test_db')

How do we work around this?

I'd therefore like to completely change how environment variables are interpreted in BaseSettings:

from pydantic import BaseSettings

class Settings(BaseSettings):
    pg_dsn: str = 'postgres://postgres@localhost:5432/app'

    class Config:
        fields = {'pg_dsn': {'env': {'DATABASE_URL', 'PG_DSN'}}}

# or using Field (#577):
class Settings(BaseSettings):
    pg_dsn: str = Field('postgres://postgres@localhost:5432/app', env={'DATABASE_URL', 'PG_DSN'})

# creating manually for testing (here i can use the raw field name since alias hasn't changed):
settings = Settings(pg_dsn='postgres://postgres@localhost:5432/testing')

as discussed on #747 env would be completely case insensitive.

thoughts?

[dmontagu]

It would be much better if I could set multiple env varibles to inspect {'REDISCLOUD_URL', 'REDIS_URL'} or whatever.

+1

In general aliases seem to make more sense to me in the context of BaseModel than BaseSettings. This proposal seems good to me.

[skewty]

I personally prefer the 2nd Field method as a developer new to pydantic is more likely to notice and use parameters there. The nested Config from my experience with my team here is less common and comes as a surprise 🎉.

While the usage of set for env is correct in your example, I also think using a list there would be more typical and reduce confusion of it being a dict. Are the additional features of set being used? Was it chosen simply because items should be unique and because order is not important? Perhaps the ordering offered by a list is an important feature to some.

[samuelcolvin]

Yes order of env may well be important. Either should work.