From 29dcff61f265fbfe3caa4d5fca302cbdbb173267 Mon Sep 17 00:00:00 2001
From: Arieh Schneier <15041913+AriehSchneier@users.noreply.github.com>
Date: Thu, 5 Aug 2021 02:00:45 +1000
Subject: [PATCH] AllKeys() should include slices allowing overriding of keys
 with slices with environment variables

---
 viper.go      | 54 +++++++++++++++++++++++++++++++++++++++++++++++++--
 viper_test.go | 34 +++++++++++++++++++++++++++++---
 2 files changed, 83 insertions(+), 5 deletions(-)

diff --git a/viper.go b/viper.go
index 46b1a85..329abd2 100644
--- a/viper.go
+++ b/viper.go
@@ -1035,8 +1035,8 @@ func (v *Viper) Unmarshal(rawVal interface{}, opts ...DecoderConfigOption) error
 	return decode(v.AllSettings(), defaultDecoderConfig(rawVal, opts...))
 }
 
-// defaultDecoderConfig returns default mapsstructure.DecoderConfig with suppot
-// of time.Duration values & string slices
+// defaultDecoderConfig returns a default mapstructure.DecoderConfig with support
+// for time.Duration values & string slices
 func defaultDecoderConfig(output interface{}, opts ...DecoderConfigOption) *mapstructure.DecoderConfig {
 	c := &mapstructure.DecoderConfig{
 		Metadata:         nil,
@@ -1976,6 +1976,8 @@ func (v *Viper) flattenAndMergeMap(shadow map[string]bool, m map[string]interfac
 			m2 = val.(map[string]interface{})
 		case map[interface{}]interface{}:
 			m2 = cast.ToStringMap(val)
+		case []interface{}:
+			m2 = castSliceToStringMap(val.([]interface{}))
 		default:
 			// immediate value
 			shadow[strings.ToLower(fullKey)] = true
@@ -1987,6 +1989,17 @@ func (v *Viper) flattenAndMergeMap(shadow map[string]bool, m map[string]interfac
 	return shadow
 }
 
+// castSliceToStringMap converts a slice to a map where the keys are the indices.
+func castSliceToStringMap(v []interface{}) map[string]interface{} {
+	m := make(map[string]interface{}, len(v))
+
+	for i, val := range v {
+		m[strconv.Itoa(i)] = val
+	}
+
+	return m
+}
+
 // mergeFlatMap merges the given maps, excluding values of the second map
 // shadowed by values from the first map.
 func (v *Viper) mergeFlatMap(shadow map[string]bool, m map[string]interface{}) map[string]bool {
@@ -2028,9 +2041,46 @@ func (v *Viper) AllSettings() map[string]interface{} {
 		// set innermost value
 		deepestMap[lastKey] = value
 	}
+
+	// convert any maps of integer keys back to slices
+	i := convertMapsToSlices(m)
+	if m2, ok := i.(map[string]interface{}); ok {
+		m = m2
+	}
+
 	return m
 }
 
+// convertMapsToSlices will do a deep check for any maps where the keys are all integers (as strings)
+// as well as being contiguous from 0, and convert them to a slice.
+func convertMapsToSlices(m map[string]interface{}) interface{} {
+	allInts := true
+	for k, v := range m {
+		if _, ok := strconv.Atoi(k); ok != nil {
+			allInts = false
+		}
+
+		if m2, ok := v.(map[string]interface{}); ok {
+			m[k] = convertMapsToSlices(m2)
+		}
+	}
+
+	if !allInts {
+		return m
+	}
+
+	s := make([]interface{}, len(m))
+	for i := 0; i < len(m); i++ {
+		v, ok := m[strconv.Itoa(i)]
+		if !ok {
+			return m
+		}
+		s[i] = v
+	}
+
+	return s
+}
+
 // SetFs sets the filesystem to use to read configuration.
 func SetFs(fs afero.Fs) { v.SetFs(fs) }
 
diff --git a/viper_test.go b/viper_test.go
index 4192748..ee3bf2a 100644
--- a/viper_test.go
+++ b/viper_test.go
@@ -570,6 +570,29 @@ func TestAutoEnv(t *testing.T) {
 	assert.Equal(t, "13", Get("foo_bar"))
 }
 
+func TestAutoEnvWithSlice(t *testing.T) {
+	initJSON()
+
+	AutomaticEnv()
+
+	type config struct {
+		Batters struct {
+			Batter []struct {
+				Type string
+			}
+		}
+	}
+
+	testutil.Setenv(t, "BATTERS.BATTER.1.TYPE", "Small")
+
+	var C config
+	err := Unmarshal(&C)
+	if err != nil {
+		t.Fatalf("unable to decode into struct, %v", err)
+	}
+	assert.Equal(t, []struct{ Type string }{{"Regular"}, {"Small"}, {"Blueberry"}, {"Devil's Food"}}, C.Batters.Batter)
+}
+
 func TestAutoEnvWithPrefix(t *testing.T) {
 	Reset()
 
@@ -620,8 +643,13 @@ func TestAllKeys(t *testing.T) {
 		"name",
 		"beard",
 		"ppu",
-		"batters.batter",
-		"hobbies",
+		"batters.batter.0.type",
+		"batters.batter.1.type",
+		"batters.batter.2.type",
+		"batters.batter.3.type",
+		"hobbies.0",
+		"hobbies.1",
+		"hobbies.2",
 		"clothing.jacket",
 		"clothing.trousers",
 		"default.import_path",
@@ -1983,7 +2011,7 @@ clothing:
 
 func TestDotParameter(t *testing.T) {
 	initJSON()
-	// shoud take precedence over batters defined in jsonExample
+	// should take precedence over batters defined in jsonExample
 	r := bytes.NewReader([]byte(`{ "batters.batter": [ { "type": "Small" } ] }`))
 	unmarshalReader(r, v.config)