feat(scan): add Scanner interface (#2317)

Signed-off-by: monkey92t <golang@88.com>

commands_test.go

@@ -14,6 +14,15 @@ import (
 	"github.com/go-redis/redis/v9/internal/proto"
 )
 
+type TimeValue struct {
+	time.Time
+}
+
+func (t *TimeValue) ScanRedis(s string) (err error) {
+	t.Time, err = time.Parse(time.RFC3339Nano, s)
+	return
+}
+
 var _ = Describe("Commands", func() {
 	ctx := context.TODO()
 	var client *redis.Client
@@ -1192,19 +1201,28 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should scan Mget", func() {
-			err := client.MSet(ctx, "key1", "hello1", "key2", 123).Err()
+			now := time.Now()
+
+			err := client.MSet(ctx, "key1", "hello1", "key2", 123, "time", now.Format(time.RFC3339Nano)).Err()
 			Expect(err).NotTo(HaveOccurred())
 
-			res := client.MGet(ctx, "key1", "key2", "_")
+			res := client.MGet(ctx, "key1", "key2", "_", "time")
 			Expect(res.Err()).NotTo(HaveOccurred())
 
 			type data struct {
-				Key1 string `redis:"key1"`
-				Key2 int    `redis:"key2"`
+				Key1 string    `redis:"key1"`
+				Key2 int       `redis:"key2"`
+				Time TimeValue `redis:"time"`
 			}
 			var d data
 			Expect(res.Scan(&d)).NotTo(HaveOccurred())
-			Expect(d).To(Equal(data{Key1: "hello1", Key2: 123}))
+			Expect(d.Time.UnixNano()).To(Equal(now.UnixNano()))
+			d.Time.Time = time.Time{}
+			Expect(d).To(Equal(data{
+				Key1: "hello1",
+				Key2: 123,
+				Time: TimeValue{Time: time.Time{}},
+			}))
 		})
 
 		It("should MSetNX", func() {
@@ -1732,19 +1750,28 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should scan", func() {
-			err := client.HMSet(ctx, "hash", "key1", "hello1", "key2", 123).Err()
+			now := time.Now()
+
+			err := client.HMSet(ctx, "hash", "key1", "hello1", "key2", 123, "time", now.Format(time.RFC3339Nano)).Err()
 			Expect(err).NotTo(HaveOccurred())
 
 			res := client.HGetAll(ctx, "hash")
 			Expect(res.Err()).NotTo(HaveOccurred())
 
 			type data struct {
-				Key1 string `redis:"key1"`
-				Key2 int    `redis:"key2"`
+				Key1 string    `redis:"key1"`
+				Key2 int       `redis:"key2"`
+				Time TimeValue `redis:"time"`
 			}
 			var d data
 			Expect(res.Scan(&d)).NotTo(HaveOccurred())
-			Expect(d).To(Equal(data{Key1: "hello1", Key2: 123}))
+			Expect(d.Time.UnixNano()).To(Equal(now.UnixNano()))
+			d.Time.Time = time.Time{}
+			Expect(d).To(Equal(data{
+				Key1: "hello1",
+				Key2: 123,
+				Time: TimeValue{Time: time.Time{}},
+			}))
 		})
 
 		It("should HIncrBy", func() {

internal/hscan/hscan.go

@@ -10,6 +10,12 @@ import (
 // decoderFunc represents decoding functions for default built-in types.
 type decoderFunc func(reflect.Value, string) error
 
+// Scanner is the interface implemented by themselves,
+// which will override the decoding behavior of decoderFunc.
+type Scanner interface {
+	ScanRedis(s string) error
+}
+
 var (
 	// List of built-in decoders indexed by their numeric constant values (eg: reflect.Bool = 1).
 	decoders = []decoderFunc{

internal/hscan/hscan_test.go

@@ -4,6 +4,7 @@ import (
 	"math"
 	"strconv"
 	"testing"
+	"time"
 
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
@@ -30,6 +31,20 @@ type data struct {
 	Bool    bool    `redis:"bool"`
 }
 
+type TimeRFC3339Nano struct {
+	time.Time
+}
+
+func (t *TimeRFC3339Nano) ScanRedis(s string) (err error) {
+	t.Time, err = time.Parse(time.RFC3339Nano, s)
+	return
+}
+
+type TimeData struct {
+	Name string           `redis:"name"`
+	Time *TimeRFC3339Nano `redis:"login"`
+}
+
 type i []interface{}
 
 func TestGinkgoSuite(t *testing.T) {
@@ -175,4 +190,14 @@ var _ = Describe("Scan", func() {
 		Expect(Scan(&d, i{"bool"}, i{""})).To(HaveOccurred())
 		Expect(Scan(&d, i{"bool"}, i{"123"})).To(HaveOccurred())
 	})
+
+	It("Implements Scanner", func() {
+		var td TimeData
+
+		now := time.Now()
+		Expect(Scan(&td, i{"name", "login"}, i{"hello", now.Format(time.RFC3339Nano)})).NotTo(HaveOccurred())
+		Expect(td.Name).To(Equal("hello"))
+		Expect(td.Time.UnixNano()).To(Equal(now.UnixNano()))
+		Expect(td.Time.Format(time.RFC3339Nano)).To(Equal(now.Format(time.RFC3339Nano)))
+	})
 })

internal/hscan/structmap.go

@@ -84,7 +84,29 @@ func (s StructValue) Scan(key string, value string) error {
 	if !ok {
 		return nil
 	}
-	if err := field.fn(s.value.Field(field.index), value); err != nil {
+
+	v := s.value.Field(field.index)
+	isPtr := v.Kind() == reflect.Pointer
+
+	if isPtr && v.IsNil() {
+		v.Set(reflect.New(v.Type().Elem()))
+	}
+	if !isPtr && v.Type().Name() != "" && v.CanAddr() {
+		v = v.Addr()
+		isPtr = true
+	}
+
+	if isPtr && v.Type().NumMethod() > 0 && v.CanInterface() {
+		if scan, ok := v.Interface().(Scanner); ok {
+			return scan.ScanRedis(value)
+		}
+	}
+
+	if isPtr {
+		v = v.Elem()
+	}
+
+	if err := field.fn(v, value); err != nil {
 		t := s.value.Type()
 		return fmt.Errorf("cannot scan redis.result %s into struct field %s.%s of type %s, error-%s",
 			value, t.Name(), t.Field(field.index).Name, t.Field(field.index).Type, err.Error())

redis.go

@@ -10,10 +10,14 @@ import (
 	"time"
 
 	"github.com/go-redis/redis/v9/internal"
+	"github.com/go-redis/redis/v9/internal/hscan"
 	"github.com/go-redis/redis/v9/internal/pool"
 	"github.com/go-redis/redis/v9/internal/proto"
 )
 
+// Scanner internal/hscan.Scanner exposed interface.
+type Scanner = hscan.Scanner
+
 // Nil reply returned by Redis when key does not exist.
 const Nil = proto.Nil