feat: add dotenv struct support to DotenvMarshaler

config.go

@@ -90,7 +90,7 @@ func extractContextValues(ctx context.Context) (string, Marshaler, error) {
 	}
 
 	if len(missing) > 0 {
-		return "", marshaler, errors.New(fmt.Sprintf("missing required values in context: %s", strings.Join(missing, ",")))
+		return "", marshaler, fmt.Errorf("missing required values in context: %s", strings.Join(missing, ","))
 	}
 	return name, marshaler, nil
 }

dotenv.go

@@ -0,0 +1,134 @@
+package gophig
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+
+	"github.com/joho/godotenv"
+)
+
+type DotenvMarshaler struct{}
+
+func (DotenvMarshaler) Marshal(v any) ([]byte, error) {
+	rv := reflect.ValueOf(v)
+	if rv.Kind() == reflect.Pointer {
+		rv = rv.Elem()
+	}
+	if !rv.IsValid() {
+		return nil, fmt.Errorf("DotenvMarshaler: Marshal expects a valid value")
+	}
+
+	var sb strings.Builder
+
+	switch rv.Kind() {
+	case reflect.Map:
+		m, ok := v.(map[string]string)
+		if !ok {
+			return nil, fmt.Errorf("DotenvMarshaler: Marshal expects map[string]string")
+		}
+		for key, val := range m {
+			val = strings.ReplaceAll(val, "\n", `\n`)
+			sb.WriteString(fmt.Sprintf("%s=%s\n", key, val))
+		}
+
+	case reflect.Struct:
+		rt := rv.Type()
+		for i := 0; i < rt.NumField(); i++ {
+			field := rt.Field(i)
+			fv := rv.Field(i)
+			if !fv.CanInterface() {
+				continue
+			}
+
+			key := field.Tag.Get("env")
+			if key == "" {
+				continue // skip fields without env tag
+			}
+
+			val := fmt.Sprintf("%v", fv.Interface())
+			val = strings.ReplaceAll(val, "\n", `\n`)
+			sb.WriteString(fmt.Sprintf("%s=%s\n", key, val))
+		}
+
+	default:
+		return nil, fmt.Errorf("DotenvMarshaler: unsupported type %s", rv.Kind())
+	}
+
+	return []byte(sb.String()), nil
+}
+
+func (DotenvMarshaler) Unmarshal(data []byte, v any) error {
+	envMap, err := godotenv.Unmarshal(string(data))
+	if err != nil {
+		return fmt.Errorf("DotenvMarshaler: failed to unmarshal dotenv: %w", err)
+	}
+
+	rv := reflect.ValueOf(v)
+	if rv.Kind() != reflect.Pointer || rv.IsNil() {
+		return fmt.Errorf("DotenvMarshaler: Unmarshal expects a non-nil pointer")
+	}
+
+	rvElem := rv.Elem()
+
+	switch rvElem.Kind() {
+	case reflect.Map:
+		if rvElem.Type().Key().Kind() != reflect.String || rvElem.Type().Elem().Kind() != reflect.String {
+			return fmt.Errorf("DotenvMarshaler: only map[string]string supported")
+		}
+		rvElem.Set(reflect.ValueOf(envMap))
+
+	case reflect.Struct:
+		for i := 0; i < rvElem.NumField(); i++ {
+			field := rvElem.Type().Field(i)
+			tag := field.Tag.Get("env")
+			if tag == "" {
+				tag = strings.ToUpper(field.Name)
+			}
+			if val, ok := envMap[tag]; ok {
+				f := rvElem.Field(i)
+				if f.CanSet() {
+					switch f.Kind() {
+					case reflect.String:
+						f.SetString(val)
+					case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+						var intVal int64
+						_, err := fmt.Sscan(val, &intVal)
+						if err != nil {
+							return fmt.Errorf("DotenvMarshaler: failed to parse int for field %s: %w", field.Name, err)
+						}
+						f.SetInt(intVal)
+					case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+						var uintVal uint64
+						_, err := fmt.Sscan(val, &uintVal)
+						if err != nil {
+							return fmt.Errorf("DotenvMarshaler: failed to parse uint for field %s: %w", field.Name, err)
+						}
+						f.SetUint(uintVal)
+					case reflect.Bool:
+						var boolVal bool
+						_, err := fmt.Sscan(val, &boolVal)
+						if err != nil {
+							return fmt.Errorf("DotenvMarshaler: failed to parse bool for field %s: %w", field.Name, err)
+						}
+						f.SetBool(boolVal)
+					case reflect.Float32, reflect.Float64:
+						var floatVal float64
+						_, err := fmt.Sscan(val, &floatVal)
+						if err != nil {
+							return fmt.Errorf("DotenvMarshaler: failed to parse float for field %s: %w", field.Name, err)
+						}
+						f.SetFloat(floatVal)
+					default:
+						return fmt.Errorf("DotenvMarshaler: unsupported field type %s for field %s", f.Kind(), field.Name)
+					}
+				}
+			}
+		}
+
+	default:
+		return fmt.Errorf("DotenvMarshaler: unsupported type %s", rvElem.Kind())
+	}
+
+	return nil
+}

go.mod

@@ -4,6 +4,7 @@ go 1.20
 
 require (
 	github.com/goccy/go-json v0.10.2
+	github.com/joho/godotenv v1.5.1
 	github.com/pelletier/go-toml/v2 v2.0.7
 	github.com/stretchr/testify v1.9.0
 	gopkg.in/yaml.v3 v3.0.1

go.sum

@@ -3,6 +3,8 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/goccy/go-json v0.10.2 h1:CrxCmQqYDkv1z7lO7Wbh2HN93uovUHgrECaO5ZrCXAU=
 github.com/goccy/go-json v0.10.2/go.mod h1:6MelG93GURQebXPDq3khkgXZkazVtN9CRI+MGFi0w8I=
+github.com/joho/godotenv v1.5.1 h1:7eLL/+HRGLY0ldzfGMeQkb7vMd0as4CfYvUVzLqw0N0=
+github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=
 github.com/kr/pretty v0.2.1 h1:Fmg33tUaq4/8ym9TJN1x7sLJnHVwhP33CNkpYV/7rwI=
 github.com/kr/pretty v0.2.1/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=

gophig_test.go

@@ -1,18 +1,19 @@
 package gophig_test
 
 import (
-	"github.com/restartfu/gophig"
-	"github.com/stretchr/testify/require"
 	"os"
 	"testing"
+
+	"github.com/restartfu/gophig"
+	"github.com/stretchr/testify/require"
 )
 
 type MockMarshaler struct{}
 
-func (m MockMarshaler) Marshal(interface{}) ([]byte, error) {
+func (m MockMarshaler) Marshal(any) ([]byte, error) {
 	return []byte{}, nil
 }
-func (MockMarshaler) Unmarshal([]byte, interface{}) error {
+func (MockMarshaler) Unmarshal([]byte, any) error {
 	return nil
 }
 
@@ -34,6 +35,7 @@ func TestGophig_GetConf(t *testing.T) {
 		"json",
 		"toml",
 		"yaml",
+		"env",
 	} {
 		t.Run("sample unmarshals successfully into "+ext+" sample struct", func(t *testing.T) {
 			marshaler, err := gophig.MarshalerFromExtension(ext)
@@ -62,6 +64,7 @@ func TestGophig_SetConf(t *testing.T) {
 		"json",
 		"toml",
 		"yaml",
+		"env",
 	} {
 		t.Run("sample marshals successfully into "+ext+" sample data", func(t *testing.T) {
 			marshaler, err := gophig.MarshalerFromExtension(ext)

marshal.go

@@ -25,8 +25,8 @@ func IsUnsupportedExtensionErr(err error) bool {
 
 // Marshaler is an interface that can marshal and unmarshal data.
 type Marshaler interface {
-	Marshal(v interface{}) ([]byte, error)
-	Unmarshal(data []byte, v interface{}) error
+	Marshal(v any) ([]byte, error)
+	Unmarshal(data []byte, v any) error
 }
 
 // MarshalerFromExtension is a Marshaler that uses a file extension to determine which Marshaler to use.
@@ -39,6 +39,8 @@ func MarshalerFromExtension(ext string) (Marshaler, error) {
 		return JSONMarshaler{}, nil
 	case "yaml":
 		return YAMLMarshaler{}, nil
+	case "env":
+		return DotenvMarshaler{}, nil
 	}
 	return nil, UnsupportedExtensionError{ext}
 }

tests/assets/sample.env

@@ -0,0 +1,3 @@
+NAME=jane
+SURNAME=doe
+AGE=20