Pointer structs not created with env prefixes

[mrsimonemms]

Following the issue raised in #202, if a pointer struct is used then the default object is not created - this is different to a non-pointer object. See the following example:

package main

import (
	"encoding/json"
	"fmt"
	"log"
	"os"

	"github.com/caarlos0/env/v6"
)

type Test struct {
	Str string `env:"TEST"`
}
type ComplexConfig struct {
	Foo   *Test `envPrefix:"FOO_"`
	Bar   Test  `envPrefix:"BAR_"`
	Clean *Test
}

func main() {
	os.Setenv("FOO_TEST", "kek")
	os.Setenv("BAR_TEST", "lel")

	cfg := ComplexConfig{}
	err := env.Parse(&cfg)
	if err != nil {
		log.Fatal(err)
	}
	confBytes, _ := json.Marshal(cfg)
	fmt.Printf("%s", confBytes)
}

This results in:

{"Foo":null,"Bar":{"Str":"lel"},"Clean":null}

Notice how Foo is null, but Bar has the object created.

[caarlos0]

yes, pointers need to be non-nil, otherwise env ignores them... I can't quite remember exactly why, will take a look when I have some time.

[caarlos0]

https://github.com/caarlos0/env/compare/nilptr?expand=1

this would init the pointers, but break a lot of other things... would need to investigate more... some other day

in the meantime, if anyone knows a lot about the reflect pkg and wants to take a look

[NithinGudla]

Hi @caarlos0 ,

I tried to fix the nil pointer issue,
Please take a look at this pull request once when you get some time,

#306

Changes:

1. If a struct pointer field is nil, it will be initialised first & then used for further processing.
2. If custom parse function is defined on any type, we don't traverse through the struct recursively.

Thanks

[caarlos0]

thanks @NithinGudla!