added get in set

docs/src/content/docs/commands/SET.md

@@ -8,7 +8,7 @@ The `SET` command in DiceDB is used to set the value of a key. If the key alread
 ## Syntax
 
 ```bash
-SET key value [EX seconds | PX milliseconds | EXAT unix-time-seconds | PXAT unix-time-milliseconds | KEEPTTL] [NX | XX]
+SET key value  [NX | XX] [GET] [EX seconds | PX milliseconds | EXAT unix-time-seconds | PXAT unix-time-milliseconds | KEEPTTL]
 ```
 
 ## Parameters
@@ -24,6 +24,7 @@ SET key value [EX seconds | PX milliseconds | EXAT unix-time-seconds | PXAT unix
 | `NX`      | Only set the key if it does not already exist.                            | None    | No       |
 | `XX`      | Only set the key if it already exists.                                    | None    | No       |
 | `KEEPTTL` | Retain the time-to-live associated with the key.                          | None    | No       |
+| `GET`     | Return the value of the key before setting it.                            | None    | No       |
 
 ## Return values
 
@@ -32,6 +33,8 @@ SET key value [EX seconds | PX milliseconds | EXAT unix-time-seconds | PXAT unix
 | Command is successful                       | `OK`         |
 | `NX` or `XX` conditions are not met         | `nil`        |
 | Syntax or specified constraints are invalid | error        |
+| If the `GET` option is provided              | The value of the key before setting it or error if value cannot be returned as a string |
+
 
 ## Behaviour
 
@@ -41,6 +44,7 @@ SET key value [EX seconds | PX milliseconds | EXAT unix-time-seconds | PXAT unix
 - Using the `EX`, `EXAT`, `PX` or `PXAT` options together with `KEEPTTL` is not allowed and will result in an error.
 - When provided, `EX` sets the expiry time in seconds and `PX` sets the expiry time in milliseconds.
 - The `KEEPTTL` option ensures that the key's existing TTL is retained.
+- The `GET` option can be used to return the value of the key before setting it. If the key does not exist, `nil` is returned. If the key exists but does not contain a value which can be returned as a string, an error is returned. The set operation is not performed in this case.
 
 ## Errors
 
@@ -131,3 +135,27 @@ Trying to set key `foo` with both `EX` and `KEEPTTL` will result in an error
 127.0.0.1:7379> SET foo bar EX 10 KEEPTTL
 (error) ERR syntax error
 ```
+
+### Set with GET option
+
+```bash
+127.0.0.1:7379> set foo bar
+OK
+127.0.0.1:7379> set foo bazz get
+"bar"
+```
+### Set with GET option when key does not exist
+
+```bash
+127.0.0.1:7379> set foo bazz get
+(nil)
+127.0.0.1:7379> get foo
+(nil)
+```
+
+### Set with Get with wrong type of value
+```bash
+127.0.0.1:7379> sadd foo item1
+(integer) 1
+127.0.0.1:7379> set foo bazz get
+(error) WRONGTYPE Operation against a key holding the wrong kind of value

integration_tests/commands/http/set_test.go

@@ -188,6 +188,29 @@ func TestSetWithOptions(t *testing.T) {
 			},
 			expected: []interface{}{nil, nil, "OK", nil, nil, nil},
 		},
+		{
+			name: "GET with Existing Value",
+			commands: []HTTPCommand{
+				{Command: "SET", Body: map[string]interface{}{"key": "k", "value": "v"}},
+				{Command: "SET", Body: map[string]interface{}{"key": "k", "value": "vv", "get": true}},
+			},
+			expected: []interface{}{"OK", "v"},
+		},
+		{
+			name: "GET with Non-Existing Value",
+			commands: []HTTPCommand{
+				{Command: "SET", Body: map[string]interface{}{"key": "k", "value": "vv", "get": true}},
+			},
+			expected: []interface{}{nil},
+		},
+		{
+			name: "GET with wrong type of value",
+			commands: []HTTPCommand{
+				{Command: "SADD", Body: map[string]interface{}{"key": "k", "value": "b"}},
+				{Command: "SET", Body: map[string]interface{}{"key": "k", "value": "v", "get": true}},
+			},
+			expected: []interface{}{float64(1), "WRONGTYPE Operation against a key holding the wrong kind of value"},
+		},
 	}
 
 	for _, tc := range testCases {
@@ -207,7 +230,7 @@ func TestWithKeepTTLFlag(t *testing.T) {
 	exec := NewHTTPCommandExecutor()
 	expiryTime := strconv.FormatInt(time.Now().Add(1*time.Minute).UnixMilli(), 10)
 
-	testCases := []TestCase {
+	testCases := []TestCase{
 		{
 			name: "SET WITH KEEP TTL",
 			commands: []HTTPCommand{
@@ -228,39 +251,39 @@ func TestWithKeepTTLFlag(t *testing.T) {
 		},
 		{
 			name: "SET WITH KEEPTTL with PX",
-			commands: []HTTPCommand {
+			commands: []HTTPCommand{
 				{Command: "SET", Body: map[string]interface{}{"key": "k", "value": "v", "px": 2000, "keepttl": true}},
 				{Command: "GET", Body: map[string]interface{}{"key": "k"}},
 			},
 			expected: []interface{}{"ERR syntax error", nil},
 		},
 		{
 			name: "SET WITH KEEPTTL with EX",
-			commands: []HTTPCommand {
+			commands: []HTTPCommand{
 				{Command: "SET", Body: map[string]interface{}{"key": "k", "value": "v", "ex": 3, "keepttl": true}},
 				{Command: "GET", Body: map[string]interface{}{"key": "k"}},
 			},
 			expected: []interface{}{"ERR syntax error", nil},
 		},
 		{
 			name: "SET WITH KEEPTTL with NX",
-			commands: []HTTPCommand {
+			commands: []HTTPCommand{
 				{Command: "SET", Body: map[string]interface{}{"key": "k", "value": "v", "nx": true, "keepttl": true}},
 				{Command: "GET", Body: map[string]interface{}{"key": "k"}},
 			},
 			expected: []interface{}{"OK", "v"},
 		},
 		{
 			name: "SET WITH KEEPTTL with XX",
-			commands: []HTTPCommand {
+			commands: []HTTPCommand{
 				{Command: "SET", Body: map[string]interface{}{"key": "k", "value": "v", "xx": true, "keepttl": true}},
 				{Command: "GET", Body: map[string]interface{}{"key": "k"}},
 			},
 			expected: []interface{}{nil, nil},
 		},
 		{
 			name: "SET WITH KEEPTTL with PXAT",
-			commands: []HTTPCommand {
+			commands: []HTTPCommand{
 				{Command: "SET", Body: map[string]interface{}{"key": "k", "value": "v", "pxat": expiryTime, "keepttl": true}},
 				{Command: "GET", Body: map[string]interface{}{"key": "k"}},
 			},
@@ -269,7 +292,7 @@ func TestWithKeepTTLFlag(t *testing.T) {
 		{
 
 			name: "SET WITH KEEPTTL with EXAT",
-			commands: []HTTPCommand {
+			commands: []HTTPCommand{
 				{Command: "SET", Body: map[string]interface{}{"key": "k", "value": "v", "exat": expiryTime, "keepttl": true}},
 				{Command: "GET", Body: map[string]interface{}{"key": "k"}},
 			},

integration_tests/commands/resp/set_test.go

@@ -52,6 +52,7 @@ func TestSet(t *testing.T) {
 func TestSetWithOptions(t *testing.T) {
 	conn := getLocalConnection()
 	expiryTime := strconv.FormatInt(time.Now().Add(1*time.Minute).UnixMilli(), 10)
+	defer FireCommand(conn, "FLUSHDB")
 	defer conn.Close()
 
 	testCases := []TestCase{
@@ -120,6 +121,21 @@ func TestSetWithOptions(t *testing.T) {
 			commands: []string{"SET k v XX EX 1", "GET k", "SLEEP 2", "GET k", "SET k v XX EX 1", "GET k"},
 			expected: []interface{}{"(nil)", "(nil)", "OK", "(nil)", "(nil)", "(nil)"},
 		},
+		{
+			name:     "GET with Existing Value",
+			commands: []string{"SET k v", "SET k vv GET"},
+			expected: []interface{}{"OK", "v"},
+		},
+		{
+			name:     "GET with Non-Existing Value",
+			commands: []string{"SET k vv GET"},
+			expected: []interface{}{"(nil)"},
+		},
+		{
+			name:     "GET with wrong type of value",
+			commands: []string{"sadd k v", "SET k vv GET"},
+			expected: []interface{}{int64(1), "WRONGTYPE Operation against a key holding the wrong kind of value"},
+		},
 	}
 
 	for _, tc := range testCases {

integration_tests/commands/websocket/set_test.go

@@ -121,6 +121,21 @@ func TestSetWithOptions(t *testing.T) {
 			commands: []string{"SET k v XX EX 1", "GET k", "SLEEP 2", "GET k", "SET k v XX EX 1", "GET k"},
 			expected: []interface{}{nil, nil, "OK", nil, nil, nil},
 		},
+		{
+			name:     "GET with Existing Value",
+			commands: []string{"SET k v", "SET k vv GET"},
+			expected: []interface{}{"OK", "v"},
+		},
+		{
+			name:     "GET with Non-Existing Value",
+			commands: []string{"SET k vv GET"},
+			expected: []interface{}{nil},
+		},
+		{
+			name:     "GET with wrong type of value",
+			commands: []string{"sadd k v", "SET k vv GET"},
+			expected: []interface{}{float64(1), "WRONGTYPE Operation against a key holding the wrong kind of value"},
+		},
 	}
 
 	for _, tc := range testCases {