support types that implement encoding.TextUnmarshaler

bench_test.go

@@ -6,7 +6,7 @@ import (
 	"github.com/profclems/go-dotenv"
 )
 
-func BenchmarkDotenv_LoadConfig(b *testing.B) {
+func BenchmarkDotenv_Load(b *testing.B) {
 	b.ReportAllocs()
 	for i := 0; i < b.N; i++ {
 		config := dotenv.New()
@@ -41,7 +41,7 @@ func BenchmarkDotenv_Init_GetSet(b *testing.B) {
 	})
 }
 
-func BenchmarkDotenv_LoadConfig_GetSet(b *testing.B) {
+func BenchmarkDotenv_Load_GetSet(b *testing.B) {
 	dotenv.SetConfigFile("fixtures/large.env")
 	err := dotenv.Load()
 	if err != nil {

dotenv.go

@@ -2,6 +2,7 @@ package dotenv
 
 import (
 	"bytes"
+	"encoding"
 	"fmt"
 	"os"
 	"path/filepath"
@@ -175,12 +176,22 @@ func (e *DotEnv) SetConfigFile(configFile string) {
 }
 
 // UnMarshal unmarshals the config file into a struct.
+// Recognizes the following struct tags:
+//   - env:"KEY" to specify the key name to look up in the config file
+//   - default:"value" to specify a default value if the key is not found
 func UnMarshal(v any) error {
 	return d.Unmarshal(v)
 }
 
-func (e *DotEnv) Unmarshal(v any) error {
-	val := reflect.ValueOf(v).Elem()
+func (e *DotEnv) Unmarshal(v any) (err error) {
+	defer func() {
+		if r := recover(); r != nil {
+			err = fmt.Errorf("%v", r)
+		}
+	}()
+
+	vPtr := reflect.ValueOf(v)
+	val := vPtr.Elem()
 
 	if vk := val.Kind(); vk != reflect.Struct {
 		return fmt.Errorf("expected a struct, got %T", vk)
@@ -191,28 +202,38 @@ func (e *DotEnv) Unmarshal(v any) error {
 		field := typ.Field(i)
 		fieldVal := val.Field(i)
 
-		if field.Type.Kind() == reflect.Struct {
-			if err := e.Unmarshal(fieldVal.Addr().Interface()); err != nil {
-				return err
+		getConfigVal := func() string {
+			tag := field.Tag.Get("env")
+			if tag != "" {
+				if envVal := e.GetString(tag); envVal != "" {
+					return envVal
+				}
 			}
-			continue
+			// set default value
+			if def := field.Tag.Get("default"); def != "" {
+				return def
+			}
+			return ""
 		}
 
-		tag := field.Tag.Get("env")
-		var configVal string
-		if tag != "" {
-			if envVal := e.GetString(tag); envVal != "" {
-				configVal = envVal
+		if fieldVal.CanAddr() {
+			if m, ok := fieldVal.Addr().Interface().(encoding.TextUnmarshaler); ok {
+				if err := m.UnmarshalText([]byte(getConfigVal())); err != nil {
+					return err
+				}
+				continue
 			}
 		}
-		if configVal == "" {
-			// set default value
-			if def := field.Tag.Get("default"); def != "" {
-				configVal = def
-			} else {
-				continue
+
+		if field.Type.Kind() == reflect.Struct {
+			if err := e.Unmarshal(fieldVal.Addr().Interface()); err != nil {
+				return err
 			}
+			continue
 		}
+
+		configVal := getConfigVal()
+
 		// set the value based on the field type
 		switch field.Type {
 		case reflect.TypeOf(time.Time{}):
@@ -241,7 +262,7 @@ func (e *DotEnv) Unmarshal(v any) error {
 		}
 	}
 
-	return nil
+	return err
 }
 
 // Get can retrieve any value given the key to use.

dotenv_test.go

@@ -1,6 +1,8 @@
 package dotenv_test
 
 import (
+	"encoding"
+	"log"
 	"testing"
 	"time"
 
@@ -169,3 +171,36 @@ func TestUnMarshal(t *testing.T) {
 
 	require.Equal(t, expectedConfig, config)
 }
+
+type customDuration struct {
+	value time.Duration
+}
+
+// check that it implements encoding.TextUnmarshaler
+var _ encoding.TextUnmarshaler = (*customDuration)(nil)
+
+func (c *customDuration) UnmarshalText(text []byte) error {
+	d, err := time.ParseDuration(string(text))
+	if err != nil {
+		return err
+	}
+	log.Println(d)
+	c.value = d
+	return nil
+}
+
+func TestUnMarshal_fieldWithTextUnmarshaler(t *testing.T) {
+	type config struct {
+		Interval customDuration `env:"INTERVAL" default:"15m"`
+	}
+
+	expectedConfig := config{
+		Interval: customDuration{value: 15 * time.Minute},
+	}
+	cfg := config{}
+
+	dotenv := dotenv.New()
+	err := dotenv.Unmarshal(&cfg)
+	require.NoError(t, err)
+	require.Equal(t, expectedConfig, cfg)
+}