Fix map in map (#101)

aconfig_test.go

@@ -1360,3 +1360,32 @@ func TestSliceStructs(t *testing.T) {
 		t.Fatalf("want %v, got %v", want, got)
 	}
 }
+
+func TestMapOfMap(t *testing.T) {
+	type TestConfig struct {
+		Options map[string]float64
+	}
+	var cfg TestConfig
+
+	loader := LoaderFor(&cfg, Config{
+		SkipDefaults: true,
+		SkipEnv:      true,
+		SkipFlags:    true,
+		Files:        []string{"testdata/toy.json"},
+	})
+
+	if err := loader.Load(); err != nil {
+		t.Fatal(err)
+	}
+
+	var want = TestConfig{
+		Options: map[string]float64{
+			"foo": 0.4,
+			"bar": 0.25,
+		},
+	}
+
+	if got := cfg; !reflect.DeepEqual(want, got) {
+		t.Fatalf("want %v, got %v", want, got)
+	}
+}

reflection.go

@@ -196,7 +196,26 @@ func (l *Loader) setFieldData(field *fieldData, value interface{}) error {
 		return l.setSlice(field, sliceToString(value))
 
 	case reflect.Map:
-		return l.setMap(field, fmt.Sprint(value))
+		v, ok := value.(map[string]interface{})
+		if !ok {
+			return l.setMap(field, fmt.Sprint(value))
+		}
+
+		mapp := reflect.MakeMapWithSize(field.field.Type, len(v))
+		for key, val := range v {
+			fdk := l.newSimpleFieldData(reflect.New(field.field.Type.Key()).Elem())
+			if err := l.setFieldData(fdk, key); err != nil {
+				return fmt.Errorf("incorrect map key %q: %w", key, err)
+			}
+
+			fdv := l.newSimpleFieldData(reflect.New(field.field.Type.Elem()).Elem())
+			if err := l.setFieldData(fdv, val); err != nil {
+				return fmt.Errorf("incorrect map value %q: %w", val, err)
+			}
+			mapp.SetMapIndex(fdk.value, fdv.value)
+		}
+		field.value.Set(mapp)
+		return nil
 
 	default:
 		return fmt.Errorf("type kind %q isn't supported", kind)

testdata/toy.json

@@ -0,0 +1,6 @@
+{
+  "options": {
+    "foo": 0.4,
+    "bar": 0.25
+  }
+}