Support maps in configuration structure

README.md

@@ -42,6 +42,7 @@ type bazzy struct {
 type config struct {
     Foo string
     Barry barry
+    Barries map[string]barry
     Bazzy bazzy `mapstructure:",squash"`
 }
 
@@ -50,16 +51,23 @@ type config struct {
 //  Barry:
 //    bar: 42
 //  Baz: true
+//  Barries: 
+//    key1:
+//      Bar: 255
+//    key2:
+//      Bar: 256
 //
 // And then it could be overriden by next env variables:
 //  FOO=foo
 //  BARRY_BAR=42
 //  BAZ=true
+//  BARRIES_KEY1_BAR=42
 //
 // Or with prefix:
 //  MYAPP_FOO=foo
 //  MYAPP_BARRY_BAR=42
 //  MYAPP_BAZ=true
+//  MYAPP_BARRIES_KEY1_BAR=42
 
 func main() {    
     var c config

enviper.go

@@ -55,6 +55,9 @@ func (e *Enviper) Unmarshal(rawVal interface{}) error {
 			return err
 		}
 	}
+	// We need to unmarshal before the env binding to make sure that keys of maps are bound just like the struct fields
+	// We silence errors here because we'll unmarshal a second time
+	_ = e.Viper.Unmarshal(rawVal)
 	e.readEnvs(rawVal)
 	return e.Viper.Unmarshal(rawVal)
 }
@@ -84,6 +87,13 @@ func (e *Enviper) bindEnvs(in interface{}, prev ...string) {
 		switch fv.Kind() {
 		case reflect.Struct:
 			e.bindEnvs(fv.Interface(), append(prev, tv)...)
+		case reflect.Map:
+			iter := fv.MapRange()
+			for iter.Next() {
+				if key, ok := iter.Key().Interface().(string); ok {
+					e.bindEnvs(iter.Value().Interface(), append(prev, tv, key)...)
+				}
+			}
 		default:
 			env := strings.Join(append(prev, tv), ".")
 			// Viper.BindEnv will never return error

enviper_test.go

@@ -82,6 +82,8 @@ func (s *UnmarshalSuite) TestWithEnvs() {
 	s.Equal("fooooo", c.Foo)
 	s.Equal(2, c.Bar.BAZ)
 	s.Equal(false, c.QUX.Quuux)
+	s.Equal(true, c.QuxMap["key1"].Quuux)
+	s.Equal(false, c.QuxMap["key2"].Quuux)
 
 	s.tearDownEnvConfig()
 }
@@ -139,6 +141,9 @@ type Config struct {
 	Bar struct {
 		BAZ int `mapstructure:"baz"`
 	} `mapstructure:"bar"`
+	QuxMap map[string]struct {
+		Quuux bool
+	}
 	QUX `mapstructure:",squash"`
 }
 

fixture.yaml

@@ -1,4 +1,9 @@
 Foo: foo
 bar:
   baz: 1
+QuxMap:
+  key1:
+    Quuux: false
+  key2:
+    Quuux: false
 Quuux: true

fixture_env

@@ -1,3 +1,4 @@
 PREF_FOO=fooooo
 PREF_BAR_BAZ=2
 PREF_QUUUX=false
+PREF_QUXMAP_KEY1_QUUUX=true