From 965cc033dbc3f0008e59c9eb023e05221384ffe5 Mon Sep 17 00:00:00 2001
From: Roman Leventov <leventov.ru@gmail.com>
Date: Mon, 10 Aug 2020 11:14:12 +0200
Subject: [PATCH] Add BindEnvSliceValue()

# Conflicts:
#	viper.go
---
 viper.go | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/viper.go b/viper.go
index f900e58..f7cb313 100644
--- a/viper.go
+++ b/viper.go
@@ -174,6 +174,7 @@ type Viper struct {
 	kvstore        map[string]any
 	pflags         map[string]FlagValue
 	env            map[string][]string
+	envSliceValues map[string]bool
 	aliases        map[string]string
 	typeByDefValue bool
 
@@ -204,6 +205,7 @@ func New() *Viper {
 	v.kvstore = make(map[string]any)
 	v.pflags = make(map[string]FlagValue)
 	v.env = make(map[string][]string)
+	v.envSliceValues = make(map[string]bool)
 	v.aliases = make(map[string]string)
 	v.typeByDefValue = false
 	v.logger = slog.New(&discardHandler{})
@@ -1103,6 +1105,7 @@ func (v *Viper) BindFlagValue(key string, flag FlagValue) error {
 // If more arguments are provided, they will represent the env variable names that
 // should bind to this key and will be taken in the specified order.
 // EnvPrefix will be used when set when env name is not provided.
+// Use BindEnvSliceValue() for binding slice variables.
 func BindEnv(input ...string) error { return v.BindEnv(input...) }
 
 func (v *Viper) BindEnv(input ...string) error {
@@ -1132,6 +1135,20 @@ func (v *Viper) MustBindEnv(input ...string) {
 	}
 }
 
+// BindEnvSliceValue is identical to BindEnv but converts the value of the environment variable into
+// a slice using strings.Fields(), e. g. variable with value " a b" is converted into ["a", "b"].
+func BindEnvSliceValue(input ...string) error { return v.BindEnvSliceValue(input...) }
+func (v *Viper) BindEnvSliceValue(input ...string) error {
+	if len(input) == 0 {
+		return fmt.Errorf("missing key to bind to")
+	}
+
+	key := strings.ToLower(input[0])
+	_ = v.BindEnv(input...)
+	v.envSliceValues[key] = true
+	return nil
+}
+
 // Given a key, find the value.
 //
 // Viper will check to see if an alias exists first.
@@ -1209,6 +1226,9 @@ func (v *Viper) find(lcaseKey string, flagDefault bool) any {
 		// even if it hasn't been registered, if automaticEnv is used,
 		// check any Get request
 		if val, ok := v.getEnv(v.mergeWithEnvPrefix(envKey)); ok {
+			if v.envSliceValues[envKey] {
+				return strings.Fields(val)
+			}
 			return val
 		}
 		if nested && v.isPathShadowedInAutoEnv(path) != "" {
@@ -1219,6 +1239,9 @@ func (v *Viper) find(lcaseKey string, flagDefault bool) any {
 	if exists {
 		for _, envkey := range envkeys {
 			if val, ok := v.getEnv(envkey); ok {
+				if v.envSliceValues[envkey] {
+					return strings.Fields(val)
+				}
 				return val
 			}
 		}
@@ -2025,6 +2048,7 @@ func (v *Viper) DebugTo(w io.Writer) {
 	fmt.Fprintf(w, "Override:\n%#v\n", v.override)
 	fmt.Fprintf(w, "PFlags:\n%#v\n", v.pflags)
 	fmt.Fprintf(w, "Env:\n%#v\n", v.env)
+	fmt.Fprintf(w, "Env Slice Values:\n%#v\n", v.envSliceValues)
 	fmt.Fprintf(w, "Key/Value Store:\n%#v\n", v.kvstore)
 	fmt.Fprintf(w, "Config:\n%#v\n", v.config)
 	fmt.Fprintf(w, "Defaults:\n%#v\n", v.defaults)