Python: add GETRANGE command (valkey-io#1585)

---------

Co-authored-by: Andrew Carbonetto <andrew.carbonetto@improving.com>

CHANGELOG.md

@@ -14,6 +14,7 @@
 * Python: Added XLEN command ([#1503](https://github.com/aws/glide-for-redis/pull/1503))
 * Python: Added LASTSAVE command ([#1509](https://github.com/aws/glide-for-redis/pull/1509))
 * Python: Added GETDEL command ([#1514](https://github.com/aws/glide-for-redis/pull/1514))
+* Python: Added GETRANGE command ([#1585](https://github.com/aws/glide-for-redis/pull/1585))
 * Python: Added ZINTER, ZUNION commands ([#1478](https://github.com/aws/glide-for-redis/pull/1478))
 * Python: Added SINTERCARD command ([#1511](https://github.com/aws/glide-for-redis/pull/1511))
 * Python: Added SORT command ([#1439](https://github.com/aws/glide-for-redis/pull/1439))

python/python/glide/async_commands/core.py

@@ -472,6 +472,43 @@ async def getdel(self, key: str) -> Optional[str]:
             Optional[str], await self._execute_command(RequestType.GetDel, [key])
         )
 
+    async def getrange(self, key: str, start: int, end: int) -> str:
+        """
+        Returns the substring of the string value stored at `key`, determined by the offsets `start` and `end` (both are inclusive).
+        Negative offsets can be used in order to provide an offset starting from the end of the string.
+        So `-1` means the last character, `-2` the penultimate and so forth.
+
+        If `key` does not exist, an empty string is returned. If `start` or `end`
+        are out of range, returns the substring within the valid range of the string.
+
+        See https://valkey.io/commands/getrange/ for more details.
+
+        Args:
+            key (str): The key of the string.
+            start (int): The starting offset.
+            end (int): The ending offset.
+
+        Returns:
+            str: A substring extracted from the value stored at `key`.
+
+        Examples:
+            >>> await client.set("mykey", "This is a string")
+            >>> await client.getrange("mykey", 0, 3)
+                "This"
+            >>> await client.getrange("mykey", -3, -1)
+                "ing"  # extracted last 3 characters of a string
+            >>> await client.getrange("mykey", 0, 100)
+                "This is a string"
+            >>> await client.getrange("non_existing", 5, 6)
+                ""
+        """
+        return cast(
+            str,
+            await self._execute_command(
+                RequestType.GetRange, [key, str(start), str(end)]
+            ),
+        )
+
     async def append(self, key: str, value: str) -> int:
         """
         Appends a value to a key.

python/python/glide/async_commands/transaction.py

@@ -99,6 +99,27 @@ def getdel(self: TTransaction, key: str) -> TTransaction:
         """
         return self.append_command(RequestType.GetDel, [key])
 
+    def getrange(self: TTransaction, key: str, start: int, end: int) -> TTransaction:
+        """
+        Returns the substring of the string value stored at `key`, determined by the offsets `start` and `end` (both are inclusive).
+        Negative offsets can be used in order to provide an offset starting from the end of the string.
+        So `-1` means the last character, `-2` the penultimate and so forth.
+
+        If `key` does not exist, an empty string is returned. If `start` or `end`
+        are out of range, returns the substring within the valid range of the string.
+
+        See https://valkey.io/commands/getrange/ for more details.
+
+        Args:
+            key (str): The key of the string.
+            start (int): The starting offset.
+            end (int): The ending offset.
+
+        Commands response:
+            str: A substring extracted from the value stored at `key`.
+        """
+        return self.append_command(RequestType.GetRange, [key, str(start), str(end)])
+
     def set(
         self: TTransaction,
         key: str,

python/python/tests/test_async_client.py

@@ -437,6 +437,40 @@ async def test_getdel(self, redis_client: TRedisClient):
         with pytest.raises(RequestError) as e:
             await redis_client.getdel(list_key)
 
+    @pytest.mark.parametrize("cluster_mode", [True, False])
+    @pytest.mark.parametrize("protocol", [ProtocolVersion.RESP2, ProtocolVersion.RESP3])
+    async def test_getrange(self, redis_client: TRedisClient):
+        key = get_random_string(16)
+        value = get_random_string(10)
+        non_string_key = get_random_string(10)
+
+        assert await redis_client.set(key, value) == OK
+        assert await redis_client.getrange(key, 0, 3) == value[:4]
+        assert await redis_client.getrange(key, -3, -1) == value[-3:]
+        assert await redis_client.getrange(key, 0, -1) == value
+
+        # out of range
+        assert await redis_client.getrange(key, 10, 100) == value[10:]
+        assert await redis_client.getrange(key, -200, -3) == value[-200:-2]
+        assert await redis_client.getrange(key, 100, 200) == ""
+
+        # incorrect range
+        assert await redis_client.getrange(key, -1, -3) == ""
+
+        # a redis bug, fixed in version 8: https://github.com/redis/redis/issues/13207
+        if await check_if_server_version_lt(redis_client, "8.0.0"):
+            assert await redis_client.getrange(key, -200, -100) == value[0]
+        else:
+            assert await redis_client.getrange(key, -200, -100) == ""
+
+        if await check_if_server_version_lt(redis_client, "8.0.0"):
+            assert await redis_client.getrange(non_string_key, 0, -1) == ""
+
+        # non-string key
+        assert await redis_client.lpush(non_string_key, ["_"]) == 1
+        with pytest.raises(RequestError):
+            await redis_client.getrange(non_string_key, 0, -1)
+
     @pytest.mark.parametrize("cluster_mode", [True, False])
     @pytest.mark.parametrize("protocol", [ProtocolVersion.RESP2, ProtocolVersion.RESP3])
     async def test_config_reset_stat(self, redis_client: TRedisClient):

python/python/tests/test_transaction.py

@@ -101,6 +101,8 @@ async def transaction_test(
 
     transaction.set(key, value)
     args.append(OK)
+    transaction.getrange(key, 0, -1)
+    args.append(value)
     transaction.getdel(key)
     args.append(value)
     transaction.getdel(key)