Refactor scan signature to work with Slice and StringMap cmds

Author: knadh

command.go

@@ -372,11 +372,12 @@ func (cmd *SliceCmd) String() string {
 	return cmdString(cmd, cmd.val)
 }
 
-// Scan scans the results from a key-value Redis map result set ([]interface{})
-// like HMGET and HGETALL to a destination struct.
-// The Redis keys are matched to the struct's field with the `redis` tag.
-func (cmd *SliceCmd) Scan(val interface{}) error {
-	return hscan.Scan(cmd.val, val)
+// Scan scans the results from the map into a destination struct. The map keys
+// are matched in the Redis struct fields by the `redis:"field"` tag.
+func (cmd *SliceCmd) Scan(dest interface{}) error {
+	// Pass the list of keys and values. Skip the first to args (command, key),
+	// eg: HMGET map.
+	return hscan.Scan(cmd.args[2:], cmd.val, dest)
 }
 
 func (cmd *SliceCmd) readReply(rd *proto.Reader) error {
@@ -925,6 +926,23 @@ func (cmd *StringStringMapCmd) String() string {
 	return cmdString(cmd, cmd.val)
 }
 
+// Scan scans the results from the map into a destination struct. The map keys
+// are matched in the Redis struct fields by the `redis:"field"` tag.
+func (cmd *StringStringMapCmd) Scan(dest interface{}) error {
+	// Pass the list of keys and values. Skip the first to args (command, key),
+	// eg: HGETALL map.
+	var (
+		keys = make([]interface{}, 0, len(cmd.val))
+		vals = make([]interface{}, 0, len(cmd.val))
+	)
+	for k, v := range cmd.val {
+		keys = append(keys, k)
+		vals = append(vals, v)
+	}
+
+	return hscan.Scan(keys, vals, dest)
+}
+
 func (cmd *StringStringMapCmd) readReply(rd *proto.Reader) error {
 	_, err := rd.ReadArrayReply(func(rd *proto.Reader, n int64) (interface{}, error) {
 		cmd.val = make(map[string]string, n/2)

commands_test.go

@@ -1375,6 +1375,22 @@ var _ = Describe("Commands", func() {
 			Expect(m).To(Equal(map[string]string{"key1": "hello1", "key2": "hello2"}))
 		})
 
+		It("should scan", func() {
+			err := client.HMSet(ctx, "hash", "key1", "hello1", "key2", 123).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"`
+			}
+			var d data
+			Expect(res.Scan(&d)).NotTo(HaveOccurred())
+			Expect(d).To(Equal(data{Key1: "hello1", Key2: 123}))
+		})
+
 		It("should HIncrBy", func() {
 			hSet := client.HSet(ctx, "hash", "key", "5")
 			Expect(hSet.Err()).NotTo(HaveOccurred())

internal/hscan/hscan.go

@@ -46,12 +46,11 @@ var (
 	structSpecs = newStructMap()
 )
 
-// Scan scans the results from a key-value Redis map result set ([]interface{})
-// to a destination struct. The Redis keys are matched to the struct's field
-// with the `redis` tag.
-func Scan(vals []interface{}, dest interface{}) error {
-	if len(vals)%2 != 0 {
-		return errors.New("args should have an even number of items (key-val)")
+// Scan scans the results from a key-value Redis map result set to a destination struct.
+// The Redis keys are matched to the struct's field with the `redis` tag.
+func Scan(keys []interface{}, vals []interface{}, dest interface{}) error {
+	if len(keys) != len(vals) {
+		return errors.New("args should have the same number of keys and vals")
 	}
 
 	// The destination to scan into should be a struct pointer.
@@ -72,13 +71,13 @@ func Scan(vals []interface{}, dest interface{}) error {
 	fMap := structSpecs.get(typ)
 
 	// Iterate through the (key, value) sequence.
-	for i := 0; i < len(vals); i += 2 {
-		key, ok := vals[i].(string)
+	for i := 0; i < len(vals); i++ {
+		key, ok := keys[i].(string)
 		if !ok {
 			continue
 		}
 
-		val, ok := vals[i+1].(string)
+		val, ok := vals[i].(string)
 		if !ok {
 			continue
 		}

internal/hscan/hscan_test.go

@@ -19,42 +19,42 @@ type data struct {
 	Bool   bool    `redis:"bool"`
 }
 
+type i []interface{}
+
 func TestGinkgoSuite(t *testing.T) {
 	RegisterFailHandler(Fail)
 	RunSpecs(t, "hscan")
 }
 
 var _ = Describe("Scan", func() {
 	It("catches bad args", func() {
-		var d data
+		var (
+			d data
+		)
 
-		Expect(Scan([]interface{}{}, &d)).NotTo(HaveOccurred())
+		Expect(Scan(i{}, i{}, &d)).NotTo(HaveOccurred())
 		Expect(d).To(Equal(data{}))
 
-		Expect(Scan([]interface{}{"key"}, &d)).To(HaveOccurred())
-		Expect(Scan([]interface{}{"key", "1", "2"}, &d)).To(HaveOccurred())
-		Expect(Scan([]interface{}{"key", "1"}, nil)).To(HaveOccurred())
+		Expect(Scan(i{"key"}, i{}, &d)).To(HaveOccurred())
+		Expect(Scan(i{"key"}, i{"1", "2"}, &d)).To(HaveOccurred())
+		Expect(Scan(i{"key", "1"}, i{}, nil)).To(HaveOccurred())
 
-		var i map[string]interface{}
-		Expect(Scan([]interface{}{"key", "1"}, &i)).To(HaveOccurred())
-		Expect(Scan([]interface{}{"key", "1"}, data{})).To(HaveOccurred())
-		Expect(Scan([]interface{}{"key", nil, "string", nil}, data{})).To(HaveOccurred())
+		var m map[string]interface{}
+		Expect(Scan(i{"key"}, i{"1"}, &m)).To(HaveOccurred())
+		Expect(Scan(i{"key"}, i{"1"}, data{})).To(HaveOccurred())
+		Expect(Scan(i{"key", "string"}, i{nil, nil}, data{})).To(HaveOccurred())
 	})
 
 	It("scans good values", func() {
 		var d data
 
 		// non-tagged fields.
-		Expect(Scan([]interface{}{"key", "value"}, &d)).NotTo(HaveOccurred())
+		Expect(Scan(i{"key"}, i{"value"}, &d)).NotTo(HaveOccurred())
 		Expect(d).To(Equal(data{}))
 
-		res := []interface{}{"string", "str!",
-			"byte", "bytes!",
-			"int", "123",
-			"uint", "456",
-			"float", "123.456",
-			"bool", "1"}
-		Expect(Scan(res, &d)).NotTo(HaveOccurred())
+		keys := i{"string", "byte", "int", "uint", "float", "bool"}
+		vals := i{"str!", "bytes!", "123", "456", "123.456", "1"}
+		Expect(Scan(keys, vals, &d)).NotTo(HaveOccurred())
 		Expect(d).To(Equal(data{
 			String: "str!",
 			Bytes:  []byte("bytes!"),
@@ -75,7 +75,7 @@ var _ = Describe("Scan", func() {
 			Bool   bool    `redis:"bool"`
 		}
 		var d2 data2
-		Expect(Scan(res, &d2)).NotTo(HaveOccurred())
+		Expect(Scan(keys, vals, &d2)).NotTo(HaveOccurred())
 		Expect(d2).To(Equal(data2{
 			String: "str!",
 			Bytes:  []byte("bytes!"),
@@ -85,10 +85,7 @@ var _ = Describe("Scan", func() {
 			Bool:   true,
 		}))
 
-		Expect(Scan([]interface{}{
-			"string", "",
-			"float", "1",
-			"bool", "t"}, &d)).NotTo(HaveOccurred())
+		Expect(Scan(i{"string", "float", "bool"}, i{"", "1", "t"}, &d)).NotTo(HaveOccurred())
 		Expect(d).To(Equal(data{
 			String: "",
 			Bytes:  []byte("bytes!"),
@@ -102,10 +99,7 @@ var _ = Describe("Scan", func() {
 	It("omits untagged fields", func() {
 		var d data
 
-		Expect(Scan([]interface{}{
-			"empty", "value",
-			"omit", "value",
-			"string", "str!"}, &d)).NotTo(HaveOccurred())
+		Expect(Scan(i{"empty", "omit", "string"}, i{"value", "value", "str!"}, &d)).NotTo(HaveOccurred())
 		Expect(d).To(Equal(data{
 			String: "str!",
 		}))
@@ -114,12 +108,12 @@ var _ = Describe("Scan", func() {
 	It("catches bad values", func() {
 		var d data
 
-		Expect(Scan([]interface{}{"int", "a"}, &d)).To(HaveOccurred())
-		Expect(Scan([]interface{}{"uint", "a"}, &d)).To(HaveOccurred())
-		Expect(Scan([]interface{}{"uint", ""}, &d)).To(HaveOccurred())
-		Expect(Scan([]interface{}{"float", "b"}, &d)).To(HaveOccurred())
-		Expect(Scan([]interface{}{"bool", "-1"}, &d)).To(HaveOccurred())
-		Expect(Scan([]interface{}{"bool", ""}, &d)).To(HaveOccurred())
-		Expect(Scan([]interface{}{"bool", "123"}, &d)).To(HaveOccurred())
+		Expect(Scan(i{"int"}, i{"a"}, &d)).To(HaveOccurred())
+		Expect(Scan(i{"uint"}, i{"a"}, &d)).To(HaveOccurred())
+		Expect(Scan(i{"uint"}, i{""}, &d)).To(HaveOccurred())
+		Expect(Scan(i{"float"}, i{"b"}, &d)).To(HaveOccurred())
+		Expect(Scan(i{"bool"}, i{"-1"}, &d)).To(HaveOccurred())
+		Expect(Scan(i{"bool"}, i{""}, &d)).To(HaveOccurred())
+		Expect(Scan(i{"bool"}, i{"123"}, &d)).To(HaveOccurred())
 	})
 })