Env Sourcer slices

[Paul Meier]

Is it possible to get a slice of string from an env var? Using env:"list" default:"'blue', 'red', 'green'" would not work. What I need is a []string specifically.

[Eric Fritz]

By default you can JSON-encode any of the values. Supplying ["blue", "red", "green"] should deserialize into a []string. The structtags could then be env:"list" default:"{\"blue\", \"red\", \"green\"}".

Does that work or do you need special value parsing logic?

[Paul Meier]

I've tried to use the basic JSON encoded example you provided but it responds with an error about type coercion:

returned a fatal error (failed to initialize painting (failed to load config (default value for field 'List' cannot be coerced into the expected type)

From this example:

type Paints struct {
    List []string `env:"list" default:"{\"blue\", \"red\", \"green\"}"`
}

Thats really all I need, nothing special!

[Eric Fritz]

Oops, sorry! I had a typo in the suggestion. Here's a full working example:

package main

import (
	"fmt"

	"github.com/go-nacelle/nacelle"
)

type PaintsInitializer struct{}

type Paints struct {
	List []string `env:"list" default:"[\"blue\", \"red\", \"green\"]"`
}

func (i *PaintsInitializer) Init(config nacelle.Config) error {
	p := &Paints{}
	if err := config.Load(p); err != nil {
		return err
	}

	fmt.Printf("> %#v\n", p.List)
	return nil
}

func setup(processes nacelle.ProcessContainer, services nacelle.ServiceContainer) error {
	processes.RegisterInitializer(&PaintsInitializer{})
	return nil
}

func main() {
	nacelle.NewBootstrapper("example", setup).BootAndExit()
}

Notice [] instead of {} in the default.

[Paul Meier]

Cool that works! Thanks!