Add support for encoding.TextUnmarshaler

README.md

@@ -14,13 +14,14 @@ AWS Lambda functions. It should be suitable for additional applications.
 
 Set some parameters in [AWS Parameter Store](https://docs.aws.amazon.com/systems-manager/latest/userguide/systems-manager-parameter-store.html):
 
-| Name                         | Value                | Type         | Key ID        |
-| ---------------------------- | -------------------- | ------------ | ------------- |
-| /exmaple_service/prod/debug  | false                | String       | -             |
-| /exmaple_service/prod/port   | 8080                 | String       | -             |
-| /exmaple_service/prod/user   | Ian                  | String       | -             |
-| /exmaple_service/prod/rate   | 0.5                  | String       | -             |
-| /exmaple_service/prod/secret | zOcZkAGB6aEjN7SAoVBT | SecureString | alias/aws/ssm |
+| Name                         | Value                     | Type         | Key ID        |
+| ---------------------------- | --------------------      | ------------ | ------------- |
+| /example_service/prod/debug  | false                     | String       | -             |
+| /example_service/prod/port   | 8080                      | String       | -             |
+| /example_service/prod/user   | Ian                       | String       | -             |
+| /example_service/prod/rate   | 0.5                       | String       | -             |
+| /example_service/prod/secret | zOcZkAGB6aEjN7SAoVBT      | SecureString | alias/aws/ssm |
+| /example_service/prod/ts     | 2020-04-14T21:26:00+02:00 | String       | -             |
 
 Write some code:
 
@@ -36,11 +37,13 @@ import (
 )
 
 type Config struct {
-    Debug  bool    `smm:"debug" default:"true"`
-    Port   int     `smm:"port"`
-    User   string  `smm:"user"`
-    Rate   float32 `smm:"rate"`
-    Secret string  `smm:"secret" required:"true"`
+    Debug     bool       `smm:"debug" default:"true"`
+    Port      int        `smm:"port"`
+    User      string     `smm:"user"`
+    Rate      float32    `smm:"rate"`
+    Secret    string     `smm:"secret" required:"true"`
+    Timestamp time.Time  `smm:"ts"`
+    AltIp     *net.IP    `smm:"alt_ip"`
 }
 
 func main() {
@@ -50,8 +53,8 @@ func main() {
         log.Fatal(err.Error())
     }
 
-    format := "Debug: %v\nPort: %d\nUser: %s\nRate: %f\nSecret: %s\n"
-    _, err = fmt.Printf(format, c.Debug, c.Port, c.User, c.Rate, c.Secret)
+    format := "Debug: %v\nPort: %d\nUser: %s\nRate: %f\nSecret: %s\nTimestamp: %s\nAltIp: %v\n"
+    _, err = fmt.Printf(format, c.Debug, c.Port, c.User, c.Rate, c.Secret, c.Timestamp, c.AltIp)
     if err != nil {
         log.Fatal(err.Error())
     }
@@ -66,6 +69,8 @@ Port: 8080
 User: Ian
 Rate: 0.500000
 Secret: zOcZkAGB6aEjN7SAoVBT
+Timestamp: 2020-04-14 21:26:00 +0200 +0200
+AltIp: <nil>
 ```
 
 [Additional examples](https://godoc.org/github.com/ianlopshire/go-ssm-config#pkg-examples) can be found in godoc.
@@ -101,8 +106,9 @@ ssmconfig supports these struct field types:
 * int, int8, int16, int32, int64
 * bool
 * float32, float64
+* encoding.TextUnmarshaler
 
-More supported types may be added in the future.
+More supported types may be added in the future. Field types that implement the `encoding.TextUnmarshaler` interface can be used directly or as a pointer.
 
 ## Licence
 

ssmconfig.go

@@ -3,6 +3,7 @@
 package ssmconfig
 
 import (
+	"encoding"
 	"path"
 	"reflect"
 	"strconv"
@@ -33,6 +34,8 @@ type Provider struct {
 	SSM ssmiface.SSMAPI
 }
 
+var textUnmarshalerType = reflect.TypeOf((*encoding.TextUnmarshaler)(nil)).Elem()
+
 // Process loads config values from smm (parameter store) into c. Encrypted parameters
 // will automatically be decrypted. c must be a pointer to a struct.
 //
@@ -129,7 +132,27 @@ func (p *Provider) getParameters(spec structSpec) (params map[string]string, inv
 	return params, invalidParams, nil
 }
 
+// Create a new instance of the field's type and call its UnmarshalText([]byte) method.
+// Set the value after execution and fail if the method returns an error.
+func unmarshalText(t reflect.Type, v reflect.Value, s string) error {
+	if v.IsNil() {
+		v.Set(reflect.New(t.Elem()))
+	}
+	err := v.Interface().(encoding.TextUnmarshaler).UnmarshalText([]byte(s))
+	if err != nil {
+		return errors.Errorf("could not decode %q into type %v: %v", s, t.String(), err)
+	}
+
+	return nil
+}
+
 func setValue(v reflect.Value, s string) error {
+	t := v.Type()
+	if t.Implements(textUnmarshalerType) {
+		return unmarshalText(t, v, s)
+	} else if reflect.PtrTo(t).Implements(textUnmarshalerType) {
+		return unmarshalText(t, v.Addr(), s)
+	}
 	switch v.Kind() {
 	case reflect.String:
 		v.SetString(s)

ssmconfig_test.go

@@ -2,8 +2,10 @@ package ssmconfig_test
 
 import (
 	"errors"
+	"net"
 	"reflect"
 	"testing"
+	"time"
 
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/service/ssm"
@@ -29,16 +31,22 @@ func (c *mockSSMClient) GetParameters(input *ssm.GetParametersInput) (*ssm.GetPa
 func TestProvider_Process(t *testing.T) {
 	t.Run("base case", func(t *testing.T) {
 		var s struct {
-			S1      string  `ssm:"/strings/s1"`
-			S2      string  `ssm:"/strings/s2" default:"string2"`
-			I1      int     `ssm:"/int/i1"`
-			I2      int     `ssm:"/int/i2" default:"42"`
-			B1      bool    `ssm:"/bool/b1"`
-			B2      bool    `ssm:"/bool/b2" default:"false"`
-			F321    float32 `ssm:"/float32/f321"`
-			F322    float32 `ssm:"/float32/f322" default:"42.42"`
-			F641    float64 `ssm:"/float64/f641"`
-			F642    float64 `ssm:"/float64/f642" default:"42.42"`
+			S1      string    `ssm:"/strings/s1"`
+			S2      string    `ssm:"/strings/s2" default:"string2"`
+			I1      int       `ssm:"/int/i1"`
+			I2      int       `ssm:"/int/i2" default:"42"`
+			B1      bool      `ssm:"/bool/b1"`
+			B2      bool      `ssm:"/bool/b2" default:"false"`
+			F321    float32   `ssm:"/float32/f321"`
+			F322    float32   `ssm:"/float32/f322" default:"42.42"`
+			F641    float64   `ssm:"/float64/f641"`
+			F642    float64   `ssm:"/float64/f642" default:"42.42"`
+			TU1     time.Time `ssm:"/text_unmarshaler/time1"`
+			TU2     time.Time `ssm:"/text_unmarshaler/time2" default:"2020-04-14T21:26:00+02:00"`
+			TU3     time.Time `ssm:"/text_unmarshaler/time3"`
+			TUP1    *net.IP   `ssm:"/text_unmarshaler/ipv41"`
+			TUP2    *net.IP   `ssm:"/text_unmarshaler/ipv42" default:"127.0.0.1"`
+			TUP3    *net.IP   `ssm:"/text_unmarshaler/ipv43"`
 			Invalid string
 		}
 
@@ -65,6 +73,14 @@ func TestProvider_Process(t *testing.T) {
 						Name:  aws.String("/base/float64/f641"),
 						Value: aws.String("42.42"),
 					},
+					{
+						Name:  aws.String("/base/text_unmarshaler/time1"),
+						Value: aws.String("2020-04-14T21:26:00+02:00"),
+					},
+					{
+						Name:  aws.String("/base/text_unmarshaler/ipv41"),
+						Value: aws.String("127.0.0.1"),
+					},
 				},
 			},
 		}
@@ -94,6 +110,12 @@ func TestProvider_Process(t *testing.T) {
 			"/base/float32/f322",
 			"/base/float64/f641",
 			"/base/float64/f642",
+			"/base/text_unmarshaler/time1",
+			"/base/text_unmarshaler/time2",
+			"/base/text_unmarshaler/time3",
+			"/base/text_unmarshaler/ipv41",
+			"/base/text_unmarshaler/ipv42",
+			"/base/text_unmarshaler/ipv43",
 		}
 
 		if !reflect.DeepEqual(names, expectedNames) {
@@ -130,6 +152,26 @@ func TestProvider_Process(t *testing.T) {
 		if s.F642 != 42.42 {
 			t.Errorf("Process() F642 unexpected value: want %f, have %f", 42.42, s.F642)
 		}
+		tm, _ := time.Parse(time.RFC3339, "2020-04-14T21:26:00+02:00")
+		if !s.TU1.Equal(tm) {
+			t.Errorf("Process() TU1 unexpected value: want %v, have %v", tm, s.TU1)
+		}
+		if !s.TU2.Equal(tm) {
+			t.Errorf("Process() TU2 unexpected value: want %v, have %v", tm, s.TU2)
+		}
+		if !s.TU3.Equal(time.Time{}) {
+			t.Errorf("Process() TU3 unexpected value: want %v, have %v", time.Time{}, s.TU3)
+		}
+		ip := net.ParseIP("127.0.0.1")
+		if !s.TUP1.Equal(ip) {
+			t.Errorf("Process() TUP1 unexpected value: want %v, have %v", ip, s.TUP1)
+		}
+		if !s.TUP2.Equal(ip) {
+			t.Errorf("Process() TUP2 unexpected value: want %v, have %v", ip, s.TUP2)
+		}
+		if s.TUP3 != nil {
+			t.Errorf("Process() TUP3 unexpected value: want %v, have %v", nil, s.TUP3)
+		}
 		if s.Invalid != "" {
 			t.Errorf("Process() Missing unexpected value: want %q, have %q", "", s.Invalid)
 		}
@@ -179,6 +221,24 @@ func TestProvider_Process(t *testing.T) {
 			client:    &mockSSMClient{},
 			shouldErr: true,
 		},
+		{
+			name:       "invalid unmarshal text",
+			configPath: "/base/",
+			c: &struct {
+				TU1 time.Time `ssm:"/text_unmarshaler/time1" default:"notATime"`
+			}{},
+			client:    &mockSSMClient{},
+			shouldErr: true,
+		},
+		{
+			name:       "invalid unmarshal text",
+			configPath: "/base/",
+			c: &struct {
+				TUP1 net.IP `ssm:"/text_unmarshaler/ipv41" default:"notAnIP"`
+			}{},
+			client:    &mockSSMClient{},
+			shouldErr: true,
+		},
 		{
 			name:       "missing required parameter",
 			configPath: "/base/",