From 64431f66e829f51c5b11fc9f6df6e29debc67871 Mon Sep 17 00:00:00 2001
From: Celian Garcia <celian.garcia1@gmail.com>
Date: Sun, 2 Aug 2020 13:37:50 +0200
Subject: [PATCH] Support maps in configuration structure

---
 README.md       |  8 ++++++++
 enviper.go      | 10 ++++++++++
 enviper_test.go |  5 +++++
 fixture.yaml    |  5 +++++
 fixture_env     |  1 +
 5 files changed, 29 insertions(+)

diff --git a/README.md b/README.md
index 39bb5b2..29a19e2 100644
--- a/README.md
+++ b/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
diff --git a/enviper.go b/enviper.go
index 2237619..798f319 100644
--- a/enviper.go
+++ b/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
diff --git a/enviper_test.go b/enviper_test.go
index bc15bc8..64970a8 100644
--- a/enviper_test.go
+++ b/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"`
 }
 
diff --git a/fixture.yaml b/fixture.yaml
index e6d4d39..4597de3 100644
--- a/fixture.yaml
+++ b/fixture.yaml
@@ -1,4 +1,9 @@
 Foo: foo
 bar:
   baz: 1
+QuxMap:
+  key1:
+    Quuux: false
+  key2:
+    Quuux: false
 Quuux: true
diff --git a/fixture_env b/fixture_env
index 98d818e..c3c926d 100644
--- a/fixture_env
+++ b/fixture_env
@@ -1,3 +1,4 @@
 PREF_FOO=fooooo
 PREF_BAR_BAZ=2
 PREF_QUUUX=false
+PREF_QUXMAP_KEY1_QUUUX=true