Merge pull request #501 from go-redis/feature/scan-slice

Feature/scan slice

command.go

@@ -542,6 +542,10 @@ func (cmd *StringSliceCmd) String() string {
 	return cmdString(cmd, cmd.val)
 }
 
+func (cmd *StringSliceCmd) ScanSlice(container interface{}) error {
+	return proto.ScanSlice(cmd.Val(), container)
+}
+
 func (cmd *StringSliceCmd) readReply(cn *pool.Conn) error {
 	var v interface{}
 	v, cmd.err = cn.Rd.ReadArrayReply(stringSliceParser)

commands_test.go

@@ -1264,14 +1264,19 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should HVals", func() {
-			hSet := client.HSet("hash", "key1", "hello1")
+			err := client.HSet("hash", "key1", "hello1").Err()
-			Expect(hSet.Err()).NotTo(HaveOccurred())
+			Expect(err).NotTo(HaveOccurred())
-			hSet = client.HSet("hash", "key2", "hello2")
+			err = client.HSet("hash", "key2", "hello2").Err()
-			Expect(hSet.Err()).NotTo(HaveOccurred())
+			Expect(err).NotTo(HaveOccurred())
 
-			hVals := client.HVals("hash")
+			v, err := client.HVals("hash").Result()
-			Expect(hVals.Err()).NotTo(HaveOccurred())
+			Expect(err).NotTo(HaveOccurred())
-			Expect(hVals.Val()).To(Equal([]string{"hello1", "hello2"}))
+			Expect(v).To(Equal([]string{"hello1", "hello2"}))
+
+			var slice []string
+			err = client.HVals("hash").ScanSlice(&slice)
+			Expect(err).NotTo(HaveOccurred())
+			Expect(slice).To(Equal([]string{"hello1", "hello2"}))
 		})
 
 	})

internal/proto/scan.go

@@ -3,6 +3,7 @@ package proto
 import (
 	"encoding"
 	"fmt"
+	"reflect"
 
 	"gopkg.in/redis.v5/internal"
 )
@@ -105,3 +106,26 @@ func Scan(b []byte, v interface{}) error {
 			"redis: can't unmarshal %T (consider implementing BinaryUnmarshaler)", v)
 	}
 }
+
+func ScanSlice(data []string, slice interface{}) error {
+	v := reflect.ValueOf(slice)
+	if !v.IsValid() {
+		return fmt.Errorf("redis: ScanSlice(nil)")
+	}
+	if v.Kind() != reflect.Ptr {
+		return fmt.Errorf("redis: ScanSlice(non-pointer %T)", slice)
+	}
+	v = v.Elem()
+	if v.Kind() != reflect.Slice {
+		return fmt.Errorf("redis: ScanSlice(non-slice %T)", slice)
+	}
+
+	for i, s := range data {
+		elem := internal.SliceNextElem(v)
+		if err := Scan([]byte(s), elem.Addr().Interface()); err != nil {
+			return fmt.Errorf("redis: ScanSlice(index=%d value=%q) failed: %s", i, s, err)
+		}
+	}
+
+	return nil
+}

internal/proto/scan_test.go

@@ -0,0 +1,48 @@
+package proto
+
+import (
+	"encoding/json"
+
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+type testScanSliceStruct struct {
+	ID   int
+	Name string
+}
+
+func (s *testScanSliceStruct) MarshalBinary() ([]byte, error) {
+	return json.Marshal(s)
+}
+
+func (s *testScanSliceStruct) UnmarshalBinary(b []byte) error {
+	return json.Unmarshal(b, s)
+}
+
+var _ = Describe("ScanSlice", func() {
+	data := []string{
+		`{"ID":-1,"Name":"Back Yu"}`,
+		`{"ID":1,"Name":"szyhf"}`,
+	}
+
+	It("[]testScanSliceStruct", func() {
+		var slice []testScanSliceStruct
+		err := ScanSlice(data, &slice)
+		Expect(err).NotTo(HaveOccurred())
+		Expect(slice).To(Equal([]testScanSliceStruct{
+			{-1, "Back Yu"},
+			{1, "szyhf"},
+		}))
+	})
+
+	It("var testContainer []*testScanSliceStruct", func() {
+		var slice []*testScanSliceStruct
+		err := ScanSlice(data, &slice)
+		Expect(err).NotTo(HaveOccurred())
+		Expect(slice).To(Equal([]*testScanSliceStruct{
+			{-1, "Back Yu"},
+			{1, "szyhf"},
+		}))
+	})
+})

internal/util.go

@@ -1,5 +1,7 @@
 package internal
 
+import "reflect"
+
 func ToLower(s string) string {
 	if isLower(s) {
 		return s
@@ -25,3 +27,21 @@ func isLower(s string) bool {
 	}
 	return true
 }
+
+func SliceNextElem(v reflect.Value) reflect.Value {
+	if v.Len() < v.Cap() {
+		v.Set(v.Slice(0, v.Len()+1))
+		return v.Index(v.Len() - 1)
+	}
+
+	elemType := v.Type().Elem()
+
+	if elemType.Kind() == reflect.Ptr {
+		elem := reflect.New(elemType.Elem())
+		v.Set(reflect.Append(v, elem))
+		return elem.Elem()
+	}
+
+	v.Set(reflect.Append(v, reflect.Zero(elemType)))
+	return v.Index(v.Len() - 1)
+}