Unprefixed value is used if prefixed value is not available about envconfig HOT 4 CLOSED

Had to fix it for my project so ended up creating a pull request anyway: #15

from envconfig.

We still get this problem when adding a tag. For example, in the code bellow I expected to fill the T.Thing only when there's a MYAPP_THING environment variable. But it accepts a THING environment variable.

package main

import (
	"fmt"
	"os"

	"github.com/kelseyhightower/envconfig"
)

type T struct {
	Thing string `envconfig:"thing"`
}

func main() {
	os.Setenv("THING", "123")
	t := T{}
	envconfig.Process("myapp", &t)
	fmt.Printf("This should be empty: %v", t.Thing)
}

This problem was introduced by the varInfo.Alt attribute in PR #61. We use the Alt whenever the varInfo.Key wasn't found, but Alt doesn't have the prefix in it. Is there any reason to why we don't add prefix to varInfo.Alt? @davidkbainbridge

from envconfig.

@rafaeljusto Attempting to think back, so please be patient ...

As I recall when I was doing the update the alt specification was documented as not using the prefix, but instead being the directly used for looking up a value. I believe, but haven't verified, that this is how the tests cases were designed as well.

from envconfig.

You are right! This behavior is much older than your PR. It was introduced in the commit fab02b3 and is also documented in README:

If envconfig can't find an environment variable in the form PREFIX_MYVAR, and there is a struct tag defined, it will try to populate your variable with an environment variable that directly matches the envconfig tag in your struct definition

Thanks!

from envconfig.