Check that env is not empty

[koterin]

We have a required flag that ensures that env is set. But it doesn't check if it's just listed or really set to any value.
It's crucial for most apps I'm working with and can help with throwing away ugly validators like this

...
if cfg.URL == "" {
    return errors.New("URL can't be empty")
}
...

This feature is also present in some other libs as notEmpty.

I suggest we add it here as well so providing a notEmpty flag would make a comparison of the env to its zero type value and throw parsing error as a result

[cristaloleg]

Hi,

if it's just listed or really set to any value.

basically you're describing a case when FOO= (which is set but empty), am I right?

[koterin]

Hi,

if it's just listed or really set to any value.

basically you're describing a case when FOO= (which is set but empty), am I right?

Yeap, there are many cases when providing an empty value is fatal for the app in some further from initialization step. So we use those “ifs”, while having that flag in lib would be super comfy.

I may create a PR, if everyone likes the idea

[cristaloleg]

I'm fine with it. Looks like the check should be added here (rough idea, haven't checked yet)

aconfig/aconfig.go

Line 266 in c6faa7e

if field.isSet {

Feel free to submit a PR, thanks!

[cristaloleg]

@koterin hey, can I assign it to you? (it's fine if you don't wanna take it, I will)

[koterin]

No, it's fine, I'll take it