load_dotenv() returns True even if .env file is not found

[scollovati]

This behaviour is not ideal since if the configuration file is not found in the filesystem it may be better to return False.
In this way the user can write something like:

if load_dotenv():
    #do stuff
else
    print("No file .env found")

Steps to reproduce

In [1]: import dotenv

In [2]: dotenv.load_dotenv()
Out[2]: True

In [3]: dotenv.find_dotenv()
Out[3]: ''

[theskumar]

I understand the return response for load_dotenv is not ideal, but at the same time as load_dotenv just not accepts a file on the filesystem but a StringIO as well, so the return value indicating the existing of a file doesn't make any sense.

There are other ways to get around this for you use case.

1. Enable verbose=True in load_dotenv to get a error log if file is not found.
2. Use the find_dotenv function to check if the file exist or not or simply check the file yourself, before loading the values from .env.

It feel like exposing an instance of Dotenv class might make sense here or None if nothing is processed by load_dotenv. cc: @bbc2 thoughts?

[bbc2]

so the return value indicating the existing of a file doesn't make any sense.

I think it would be OK to return True if a StringIO was provided. False would still be useful for users using files.

So I'd suggest implementing that, or changing strategies and adding a raise_if_file_not_found argument to load_dotenv and dotenv_values. One or the other, but not both.

It feel like exposing an instance of Dotenv class might make sense here or None if nothing is processed by load_dotenv.

Although it could lead to interesting features, I'm worried that exposing the Dotenv class would increase our API surface considerably. I kind of like the fact that we can change that class easily at the moment, which wouldn't be the case if we exposed it to users.

About returning None, what would be the advantage compared to returning False?

[iamsannyrai]

@theskumar why we can access values from .env files by just os.getenv("VARIABLE_NAME") without even calling load_env() ? Any reason?

[ethsanders]

@theskumar why we can access values from .env files by just os.getenv("VARIABLE_NAME") without even calling load_env() ? Any reason?

load_env sets the environment variables of the python instance to the ones found in the file. If you don't call I, then it uses the local variables of the system.

[larsks]

I've submitted a PR that changes the behavior of dotenv.Dotenv.set_as_environment_variables such that load_dotenv will return False if it is unable to load any environment variables from a file or stream. I think that addresses the concerns raised in this issue.

[rptaylor]

I think this is the same or similar to #297 ?