Recursively construct toml key (#7)

config.go

@@ -31,7 +31,7 @@ func Load(filepath string, dst interface{}) error {
 		return err
 	}
 
-	return bindFlags(dst, metadata)
+	return bindFlags(dst, metadata, "")
 }
 
 // bindEnvVariables will bind CLI flags to their respective elements in dst, defined by the struct-tag "env".
@@ -65,7 +65,7 @@ func bindEnvVariables(dst interface{}) error {
 }
 
 // bindFlags will bind CLI flags to their respective elements in dst, defined by the struct-tag "flag".
-func bindFlags(dst interface{}, metadata toml.MetaData) error {
+func bindFlags(dst interface{}, metadata toml.MetaData, fieldPath string) error {
 	fields := structs.Fields(dst)
 	for _, field := range fields {
 		tag := field.Tag(flagTag)
@@ -75,7 +75,18 @@ func bindFlags(dst interface{}, metadata toml.MetaData) error {
 				continue
 			}
 
-			if err := bindFlags(dstElem.Addr().Interface(), metadata); err != nil {
+			var path string
+			if fieldPath != "" {
+				path = fmt.Sprintf("%s.", fieldPath)
+			}
+
+			if field.Tag(tomlTag) != "" {
+				path += field.Tag(tomlTag)
+			} else {
+				path += field.Name()
+			}
+
+			if err := bindFlags(dstElem.Addr().Interface(), metadata, path); err != nil {
 				return err
 			}
 
@@ -91,7 +102,15 @@ func bindFlags(dst interface{}, metadata toml.MetaData) error {
 		useFlagDefaultValue := false
 		if !isFlagSet(tag) {
 			_, envHasKey := os.LookupEnv(field.Tag(envTag))
-			if envHasKey || tomlHasKey(metadata, field.Tag(tomlTag)) {
+
+			var tomlKey string
+			if fieldPath == "" {
+				tomlKey = field.Tag(tomlTag)
+			} else {
+				tomlKey = fmt.Sprintf("%s.%s", fieldPath, field.Tag(tomlTag))
+			}
+
+			if envHasKey || tomlHasKey(metadata, tomlKey) {
 				continue
 			} else {
 				useFlagDefaultValue = true
@@ -190,10 +209,10 @@ func isFlagSet(tag string) bool {
 	return flagSet
 }
 
-// tomlHasKey will check if the tag presents in toml metadata
-func tomlHasKey(metadata toml.MetaData, tag string) bool {
+// tomlHasKey will check if the toml key presents in toml metadata
+func tomlHasKey(metadata toml.MetaData, tomlKey string) bool {
 	for _, key := range metadata.Keys() {
-		if strings.ToLower(key.String()) == strings.ToLower(tag) {
+		if strings.EqualFold(key.String(), tomlKey) {
 			return true
 		}
 	}

config_test.go

@@ -428,6 +428,70 @@ LogLevel = "debug"
 	}
 }
 
+func TestLoad_TomlNested_FlagSetAndNotGiven(t *testing.T) {
+	var cfg struct {
+		DB struct {
+			Account     string `toml:"account" flag:"db-account"`
+			Username    string `toml:"username" flag:"db-user"`
+			Credentials struct {
+				Secret   string `toml:"secret" flag:"db-secret"`
+				Password string `toml:"password" flag:"db-password"`
+			} `toml:"credentials"`
+			Options *struct {
+				Port int `toml:"port" flag:"db-port"`
+			}
+		} `toml:"database"`
+	}
+	tmp, _ := ioutil.TempFile("", "")
+	defer os.Remove(tmp.Name())
+
+	_, err := tmp.WriteString(`
+[database]
+account = "test_account"
+username = "test_user"
+[database.credentials]
+secret = "wowowow"
+password = "12345"
+[database.options]
+port = 3306
+`)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	fs := flag.NewFlagSet("tmp", flag.ExitOnError)
+	_ = fs.String("db-account", "default", "")
+	_ = fs.String("db-user", "default", "")
+	_ = fs.String("db-secret", "default", "")
+	_ = fs.String("db-password", "default", "")
+	_ = fs.Int("db-port", 0, "")
+	flag.CommandLine = fs
+
+	if err := Load(tmp.Name(), &cfg); err != nil {
+		t.Fatalf("unexpected error %v", err)
+	}
+
+	if cfg.DB.Account != "test_account" {
+		t.Errorf("got: %v, expected: %v", cfg.DB.Account, "test_account")
+	}
+
+	if cfg.DB.Username != "test_user" {
+		t.Errorf("got: %v, expected: %v", cfg.DB.Username, "test_user")
+	}
+
+	if cfg.DB.Credentials.Secret != "wowowow" {
+		t.Errorf("got: %v, expected: %v", cfg.DB.Credentials.Secret, "wowowow")
+	}
+
+	if cfg.DB.Credentials.Password != "12345" {
+		t.Errorf("got: %v, expected: %v", cfg.DB.Credentials.Password, "12345")
+	}
+
+	if cfg.DB.Options.Port != 3306 {
+		t.Errorf("got: %v, expected: %v", cfg.DB.Options.Port, 3306)
+	}
+}
+
 func TestLoad_EnvGivenWithNested(t *testing.T) {
 	os.Clearenv()
 	var cfg struct {