Adding time.Duration support (#12)

Author: jeeyoungk

README.md

@@ -37,6 +37,8 @@ type serverEnvVars struct {
 	// time.Time in order to set the value of the field. In this case, the
 	// UnmarshalText method expects the string value to be in RFC 3339 format.
 	StartTime time.Time `envvar:"START_TIME" default:"2017-10-31T14:18:00Z"`
+	// Duration is supported via time.ParseDuration()
+	Timeout time.Duration `envvar:"TIMEOUT" default:"30m"`
 }
 
 func main() {

envvar/envvar.go

@@ -10,6 +10,7 @@ import (
 	"strconv"
 	"strings"
 	"syscall"
+	"time"
 )
 
 // Parse parses environment variables into v, which must be a pointer to a
@@ -191,11 +192,20 @@ func setFieldVal(structField reflect.Value, name string, v string) error {
 	case reflect.String:
 		structField.SetString(v)
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
-		vInt, err := strconv.Atoi(v)
-		if err != nil {
-			return InvalidVariableError{name, v, err}
+		if structField.Type() == reflect.TypeOf(time.Duration(0)) {
+			// special handling for duration types.
+			dur, err := time.ParseDuration(v)
+			if err != nil {
+				return InvalidVariableError{name, v, err}
+			}
+			structField.SetInt(int64(dur))
+		} else {
+			vInt, err := strconv.Atoi(v)
+			if err != nil {
+				return InvalidVariableError{name, v, err}
+			}
+			structField.SetInt(int64(vInt))
 		}
-		structField.SetInt(int64(vInt))
 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
 		vUint, err := strconv.ParseUint(v, 10, 64)
 		if err != nil {

envvar/envvar_test.go

@@ -85,21 +85,22 @@ func TestParseCustomNames(t *testing.T) {
 
 func TestParseDefaultVals(t *testing.T) {
 	expected := defaultVars{
-		STRING:  "foo",
-		INT:     272309480983,
-		INT8:    -4,
-		INT16:   15893,
-		INT32:   -230984,
-		INT64:   12,
-		UINT:    42,
-		UINT8:   13,
-		UINT16:  1337,
-		UINT32:  348904,
-		UINT64:  12093803,
-		FLOAT32: 0.001234,
-		FLOAT64: 23.7,
-		BOOL:    true,
-		TIME:    time.Date(1992, 9, 29, 0, 0, 0, 0, time.UTC),
+		STRING:   "foo",
+		INT:      272309480983,
+		INT8:     -4,
+		INT16:    15893,
+		INT32:    -230984,
+		INT64:    12,
+		UINT:     42,
+		UINT8:    13,
+		UINT16:   1337,
+		UINT32:   348904,
+		UINT64:   12093803,
+		FLOAT32:  0.001234,
+		FLOAT64:  23.7,
+		BOOL:     true,
+		DURATION: time.Minute * 30,
+		TIME:     time.Date(1992, 9, 29, 0, 0, 0, 0, time.UTC),
 		CUSTOM: customUnmarshaler{
 			strings: []string{"one", "two", "three"},
 		},
@@ -365,23 +366,24 @@ type customNamedVars struct {
 }
 
 type defaultVars struct {
-	STRING  string                   `default:"foo"`
-	INT     int                      `default:"272309480983"`
-	INT8    int8                     `default:"-4"`
-	INT16   int16                    `default:"15893"`
-	INT32   int32                    `default:"-230984"`
-	INT64   int64                    `default:"12"`
-	UINT    uint                     `default:"42"`
-	UINT8   uint8                    `default:"13"`
-	UINT16  uint16                   `default:"1337"`
-	UINT32  uint32                   `default:"348904"`
-	UINT64  uint64                   `default:"12093803"`
-	FLOAT32 float32                  `default:"0.001234"`
-	FLOAT64 float64                  `default:"23.7"`
-	BOOL    bool                     `default:"true"`
-	TIME    time.Time                `default:"1992-09-29T00:00:00Z"`
-	CUSTOM  customUnmarshaler        `default:"one,two,three"`
-	WRAPPER customUnmarshalerWrapper `default:"apple,banana,cranberry"`
+	STRING   string                   `default:"foo"`
+	INT      int                      `default:"272309480983"`
+	INT8     int8                     `default:"-4"`
+	INT16    int16                    `default:"15893"`
+	INT32    int32                    `default:"-230984"`
+	INT64    int64                    `default:"12"`
+	UINT     uint                     `default:"42"`
+	UINT8    uint8                    `default:"13"`
+	UINT16   uint16                   `default:"1337"`
+	UINT32   uint32                   `default:"348904"`
+	UINT64   uint64                   `default:"12093803"`
+	FLOAT32  float32                  `default:"0.001234"`
+	FLOAT64  float64                  `default:"23.7"`
+	BOOL     bool                     `default:"true"`
+	DURATION time.Duration            `default:"30m"`
+	TIME     time.Time                `default:"1992-09-29T00:00:00Z"`
+	CUSTOM   customUnmarshaler        `default:"one,two,three"`
+	WRAPPER  customUnmarshalerWrapper `default:"apple,banana,cranberry"`
 }
 
 type customNameAndDefaultVars struct {