Redis Command: LSET - BigBoxCode

Summary

Command Name	LSET
Usage	Change list value at specific index
Group	list
ACL Category	@write @list @slow
Time Complexity	O(N)
Flag	WRITE DENYOOM
Arity	4

Notes

In the time complexity, N is the length of the list.
Setting the first and/or last element of the list has a time complexity of O(1).

Signature

LSET <key> <index> <new_item>

Usage

Change/replace value at a specific index of a list. For the command to work there should be an existing list, with some items and we can only change items that are already set(have an index).

Both positive and negative indexes will work for this command.

Notes

Index is zero(0) based. So the first item is considered at index Zero(0).

Arguments

Parameter	Description	Name	Type
<key>	Name of the key of the list	key	key
<index>	Index of list where we want to replace the value	index	integer
<new_item>	New value that will replace the existing item	element	string

Return Value

Return value	Case for the return value	Type
OK	On successful execution of the command	const
error	If the index is out of range, the list does not exist or provided key is not of a list	error

Notes

If the type of the value in the provided key is not a string then the following error is returned-
(error) WRONGTYPE Operation against a key holding the wrong kind of value
If the provided key of the list does not exist then the following error is returned-
(error) ERR no such key
If the provided <index> is out of range of the list, then the following error is returned-
(error) ERR index out of range

Examples

Here are a few examples of the LSET command usage-

# Redis LSET command examples

# Push some value to list
127.0.0.1:6379> rpush bigboxlist "Item A" "Item B" "Item C" "Item D" "Item E"
(integer) 5

# Check list
127.0.0.1:6379> lrange bigboxlist 0 -1
1) "Item A"
2) "Item B"
3) "Item C"
4) "Item D"
5) "Item E"

# Set value at index 0
127.0.0.1:6379> lset bigboxlist 0 "Changed item AAAA"
OK

# Set value at index 2 of list
127.0.0.1:6379> lset bigboxlist 2 "Changed item CCCC"
OK

# Set value at index -1 of list
127.0.0.1:6379> lset bigboxlist -1 "Changed item EEEE"
OK

# Check list value
127.0.0.1:6379> lrange bigboxlist 0 -1
1) "Changed item AAAA"
2) "Item B"
3) "Changed item CCCC"
4) "Item D"
5) "Changed item EEEE"

# Try to set value at some out of range index
# error returned
127.0.0.1:6379> lset bigboxlist 200 "Some out of range dummy"
(error) ERR index out of range

# Try to set value at some out of range index
# error returned
127.0.0.1:6379> lset bigboxlist -100 "Another out of range dummy"
(error) ERR index out of range

# Try to use LSET on a non existing list
# We get an error
127.0.0.1:6379> lset nonexistinglist 0 "My value 101"
(error) ERR no such key

# Set some string value
127.0.0.1:6379> set bigboxstr "some string value here"
OK

# Try to use LSET for a string
# error returned as LSET can only be used on a list
127.0.0.1:6379> lset bigboxstr 0 "use lset for str"
(error) WRONGTYPE Operation against a key holding the wrong kind of value

Notes

We can not set any new index using LSET. Only can change/replace existing index value.

Code Implementations

Here are the usage examples of the Redis LSET command in different programming languages.

Go
NodeJS

Python
Ruby

// Redis LSET command example in Golang

package main

import (
	"context"
	"fmt"

	"github.com/redis/go-redis/v9"
)

var rdb *redis.Client
var ctx context.Context

func init() {
	rdb = redis.NewClient(&redis.Options{
		Addr:     "localhost:6379",
		Username: "default",
		Password: "",
		DB:       0,
	})

	ctx = context.Background()
}

func main() {

	// Push some value to list
	// Command: rpush bigboxlist "Item A" "Item B" "Item C" "Item D" "Item E"
	// Result: (integer) 5
	rpushResult, err := rdb.RPush(ctx, "bigboxlist", "Item A", "Item B", "Item C", "Item D", "Item E").Result()

	if err != nil {
		fmt.Println("Command: rpush bigboxlist \"Item A\" \"Item B\" \"Item C\" \"Item D\" \"Item E\" | Error: " + err.Error())
	}

	fmt.Println("Command: rpush bigboxlist \"Item A\" \"Item B\" \"Item C\" \"Item D\" \"Item E\" | Result: ", rpushResult)

	// Check list
	// Command: lrange bigboxlist 0 -1
	// Result:
	//          1) "Item A"
	//          2) "Item B"
	//          3) "Item C"
	//          4) "Item D"
	//          5) "Item E"
	lrangeResult, err := rdb.LRange(ctx, "bigboxlist", 0, -1).Result()

	if err != nil {
		fmt.Println("Command: lrange bigboxlist 0 -1 | Error: " + err.Error())
	}

	fmt.Println("Command: lrange bigboxlist 0 -1 | Result: ", lrangeResult)

	// Set value at index 0
	// Command: lset bigboxlist 0 "Changed item AAAA"
	// Result: OK
	lsetResult, err := rdb.LSet(ctx, "bigboxlist", 0, "Changed item AAAA").Result()

	if err != nil {
		fmt.Println("Command: lset bigboxlist 0 \"Changed item AAAA\" | Error: " + err.Error())
	}

	fmt.Println("Command: lset bigboxlist 0 \"Changed item AAAA\" | Result: " + lsetResult)

	// Set value at index 2 of list
	// Command: lset bigboxlist 2 "Changed item CCCC"
	// Result: OK
	lsetResult, err = rdb.LSet(ctx, "bigboxlist", 2, "Changed item CCCC").Result()

	if err != nil {
		fmt.Println("Command: lset bigboxlist 2 \"Changed item CCCC\" | Error: " + err.Error())
	}

	fmt.Println("Command: lset bigboxlist 2 \"Changed item CCCC\" | Result: " + lsetResult)

	// Set value at index -1 of list
	// Command: lset bigboxlist -1 "Changed item EEEE"
	// Result: OK
	lsetResult, err = rdb.LSet(ctx, "bigboxlist", -1, "Changed item EEEE").Result()

	if err != nil {
		fmt.Println("Command: lset bigboxlist -1 \"Changed item EEEE\" | Error: " + err.Error())
	}

	fmt.Println("Command: lset bigboxlist -1 \"Changed item EEEE\" | Result: " + lsetResult)

	// Check list value
	// Command: lrange bigboxlist 0 -1
	// Result:
	//         1) "Changed item AAAA"
	//         2) "Item B"
	//         3) "Changed item CCCC"
	//         4) "Item D"
	//         5) "Changed item EEEE"
	lrangeResult, err = rdb.LRange(ctx, "bigboxlist", 0, -1).Result()

	if err != nil {
		fmt.Println("Command: lrange bigboxlist 0 -1 | Error: " + err.Error())
	}

	fmt.Println("Command: lrange bigboxlist 0 -1 | Result: ", lrangeResult)

	// Try to set value at some out of range index
	// error returned
	// Command: lset bigboxlist 200 "Some out of range dummy"
	// Result: (error) ERR index out of range
	lsetResult, err = rdb.LSet(ctx, "bigboxlist", 200, "Some out of range dummy").Result()

	if err != nil {
		fmt.Println("Command: lset bigboxlist 200 \"Some out of range dummy\" | Error: " + err.Error())
	}

	fmt.Println("Command: lset bigboxlist 200 \"Some out of range dummy\" | Result: " + lsetResult)

	// Try to set value at some out of range index
	// error returned
	// Command: lset bigboxlist -100 "Another out of range dummy"
	// Result: (error) ERR index out of range
	lsetResult, err = rdb.LSet(ctx, "bigboxlist", -200, "Another out of range dummy").Result()

	if err != nil {
		fmt.Println("Command: lset bigboxlist -100 \"Another out of range dummy\" | Error: " + err.Error())
	}

	fmt.Println("Command: lset bigboxlist -100 \"Another out of range dummy\" | Result: " + lsetResult)

	// Try to use LSET on a non existing list
	//  We get an error
	// Command: lset nonexistinglist 0 "My value 101"
	// Result: (error) ERR no such key
	lsetResult, err = rdb.LSet(ctx, "nonexistinglist", 0, "My value 101").Result()

	if err != nil {
		fmt.Println("Command: lset nonexistinglist 0 \"My value 101\" | Error: " + err.Error())
	}

	fmt.Println("Command: lset nonexistinglist 0 \"My value 101\" | Result: " + lsetResult)

	// Set some string value
	// Command: set bigboxstr "some string value here"
	// Result: OK
	setResult, err := rdb.Set(ctx, "bigboxstr", "some string value here", 0).Result()

	if err != nil {
		fmt.Println("Command: set bigboxstr \"some string value here\" | Error: " + err.Error())
	}

	fmt.Println("Command: set bigboxstr \"some string value here\" | Result: " + setResult)

	// Try to use LSET for a string
	// error returned as LSET can only be used on a list
	// Command: lset bigboxstr 0 "use lset for str"
	// Result: (error) WRONGTYPE Operation against a key holding the wrong kind of value
	lsetResult, err = rdb.LSet(ctx, "bigboxstr", 0, "use lset for str").Result()

	if err != nil {
		fmt.Println("Command: lset bigboxstr 0 \"use lset for str\" | Error: " + err.Error())
	}

	fmt.Println("Command: lset bigboxstr 0 \"use lset for str\" | Result: " + lsetResult)

}

Output:

Command: rpush bigboxlist "Item A" "Item B" "Item C" "Item D" "Item E" | Result:  5
Command: lrange bigboxlist 0 -1 | Result:  [Item A Item B Item C Item D Item E]

Command: lset bigboxlist 0 "Changed item AAAA" | Result: OK
Command: lset bigboxlist 2 "Changed item CCCC" | Result: OK
Command: lset bigboxlist -1 "Changed item EEEE" | Result: OK

Command: lrange bigboxlist 0 -1 | Result:  [Changed item AAAA Item B Changed item CCCC Item D Changed item EEEE]

Command: lset bigboxlist 200 "Some out of range dummy" | Error: ERR index out of range
Command: lset bigboxlist 200 "Some out of range dummy" | Result:

Command: lset bigboxlist -100 "Another out of range dummy" | Error: ERR index out of range
Command: lset bigboxlist -100 "Another out of range dummy" | Result:

Command: lset nonexistinglist 0 "My value 101" | Error: ERR no such key
Command: lset nonexistinglist 0 "My value 101" | Result:

Command: set bigboxstr "some string value here" | Result: OK
Command: lset bigboxstr 0 "use lset for str" | Error: WRONGTYPE Operation against a key holding the wrong kind of value
Command: lset bigboxstr 0 "use lset for str" | Result:

Notes

Use “LSet” method from redis-go module.
Signature of the method is-
func (c cmdable) LSet(ctx context.Context, key string, index int64, value interface{}) *StatusCmd

// Redis LSET command example in JavaScript(NodeJS)

import { createClient } from "redis";

// Create redis client
const redisClient = createClient({
  url: "redis://default:@localhost:6379",
});

redisClient.on("error", (err) =>
  console.log("Error while connecting to Redis", err)
);

// Connect Redis client
await redisClient.connect();

/**
 * Push some value to list
 *
 * Command: rpush bigboxlist "Item A" "Item B" "Item C" "Item D" "Item E"
 * Result: (integer) 5
 */
let commandResult = await redisClient.rPush("bigboxlist", [
  "Item A",
  "Item B",
  "Item C",
  "Item D",
  "Item E",
]);

console.log(
  'Command: rpush bigboxlist "Item A" "Item B" "Item C" "Item D" "Item E" | Result: ' +
    commandResult
);

/**
 * Check list
 *
 * Command: lrange bigboxlist 0 -1
 * Result:
 *          1) "Item A"
 *          2) "Item B"
 *          3) "Item C"
 *          4) "Item D"
 *          5) "Item E"
 */
commandResult = await redisClient.lRange("bigboxlist", 0, -1);

console.log("Command: lrange bigboxlist 0 -1 | Result: ", commandResult);

/**
 * Set value at index 0
 *
 * Command: lset bigboxlist 0 "Changed item AAAA"
 * Result: OK
 */
commandResult = await redisClient.lSet("bigboxlist", 0, "Changed item AAAA");

console.log(
  'Command: lset bigboxlist 0 "Changed item AAAA" | Result: ' + commandResult
);

/**
 * Set value at index 2 of list
 *
 * Command: lset bigboxlist 2 "Changed item CCCC"
 * Result: OK
 */
commandResult = await redisClient.lSet("bigboxlist", 2, "Changed item CCCC");

console.log(
  'Command: lset bigboxlist 2 "Changed item CCCC" | Result: ' + commandResult
);

/**
 * Set value at index -1 of list
 *
 * Command: lset bigboxlist -1 "Changed item EEEE"
 * Result: OK
 */
commandResult = await redisClient.lSet("bigboxlist", -1, "Changed item EEEE");

console.log(
  'Command: lset bigboxlist -1 "Changed item EEEE" | Result: ' + commandResult
);

/**
 * Check list value
 *
 * Command: lrange bigboxlist 0 -1
 * Result:
 *         1) "Changed item AAAA"
 *         2) "Item B"
 *         3) "Changed item CCCC"
 *         4) "Item D"
 *         5) "Changed item EEEE"
 */
commandResult = await redisClient.lRange("bigboxlist", 0, -1);

console.log("Command: lrange bigboxlist 0 -1 | Result: ", commandResult);

/**
 * Try to set value at some out of range index
 * error returned
 *
 * Command: lset bigboxlist 200 "Some out of range dummy"
 * Result: (error) ERR index out of range
 */
try {
  commandResult = await redisClient.lSet(
    "bigboxlist",
    200,
    "Some out of range dummy"
  );

  console.log(
    'Command: lset bigboxlist 200 "Some out of range dummy" | Result: ' +
      commandResult
  );
} catch (err) {
  console.log(
    'Command: lset bigboxlist 200 "Some out of range dummy" | Error: ',
    err
  );
}

/**
 * Try to set value at some out of range index
 * error returned
 *
 * Command: lset bigboxlist -100 "Another out of range dummy"
 * Result: (error) ERR index out of range
 */
try {
  commandResult = await redisClient.lSet(
    "bigboxlist",
    -200,
    "Another out of range dummy"
  );

  console.log(
    'Command: lset bigboxlist -100 "Another out of range dummy" | Result: ' +
      commandResult
  );
} catch (err) {
  console.log(
    'Command: lset bigboxlist -100 "Another out of range dummy" | Error: ',
    err
  );
}

/**
 * Try to use LSET on a non existing list
 *  We get an error
 *
 * Command: lset nonexistinglist 0 "My value 101"
 * Result: (error) ERR no such key
 */
try {
  commandResult = await redisClient.lSet("nonexistinglist", 0, "My value 101");

  console.log(
    'Command: lset nonexistinglist 0 "My value 101" | Result: ' + commandResult
  );
} catch (err) {
  console.log('Command: lset nonexistinglist 0 "My value 101" | Error: ', err);
}

/**
 * Set some string value
 *
 * Command: set bigboxstr "some string value here"
 * Result: OK
 */
commandResult = await redisClient.set("bigboxstr", "some string value here");

console.log(
  'Command: set bigboxstr "some string value here" | Result: ' + commandResult
);

/**
 * Try to use LSET for a string
 * error returned as LSET can only be used on a list
 *
 * Command: lset bigboxstr 0 "use lset for str"
 * Result: (error) WRONGTYPE Operation against a key holding the wrong kind of value
 */
try {
  commandResult = await redisClient.lSet("bigboxstr", 0, "use lset for str");

  console.log(
    'Command: lset bigboxstr 0 "use lset for str" | Result: ' + commandResult
  );
} catch (err) {
  console.log('Command: lset bigboxstr 0 "use lset for str" | Error: ', err);
}

process.exit(0);

Output:

Command: rpush bigboxlist "Item A" "Item B" "Item C" "Item D" "Item E" | Result: 5
Command: lrange bigboxlist 0 -1 | Result:  [ 'Item A', 'Item B', 'Item C', 'Item D', 'Item E' ]

Command: lset bigboxlist 0 "Changed item AAAA" | Result: OK
Command: lset bigboxlist 2 "Changed item CCCC" | Result: OK
Command: lset bigboxlist -1 "Changed item EEEE" | Result: OK

Command: lrange bigboxlist 0 -1 | Result:  [
  'Changed item AAAA',
  'Item B',
  'Changed item CCCC',
  'Item D',
  'Changed item EEEE'
]

Command: lset bigboxlist 200 "Some out of range dummy" | Error:  [ErrorReply: ERR index out of range]
Command: lset bigboxlist -100 "Another out of range dummy" | Error:  [ErrorReply: ERR index out of range]

Command: lset nonexistinglist 0 "My value 101" | Error:  [ErrorReply: ERR no such key]

Command: set bigboxstr "some string value here" | Result: OK
Command: lset bigboxstr 0 "use lset for str" | Error:  [ErrorReply: WRONGTYPE Operation against a key holding the wrong kind of value]

Notes

Use the function “lSet” of node-redis.

Signature of the method-
lSet(key: RedisCommandArgument, index: number, element: RedisCommandArgument)

// Redis LSET Command example in Java

import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;

import java.util.List;

public class Lset {
    public static void main(String[] args) {
        // Create connection pool
        JedisPool jedisPool = new JedisPool("localhost", 6379);

        try (Jedis jedis = jedisPool.getResource()) {

            /**
             * Push some value to list
             *
             * Command: rpush bigboxlist "Item A" "Item B" "Item C" "Item D" "Item E"
             * Result: (integer) 5
             */
            long rpushResult = jedis.rpush("bigboxlist", "Item A", "Item B", "Item C", "Item D", "Item E");

            System.out.println("Command: rpush bigboxlist \"Item A\" \"Item B\" \"Item C\" \"Item D\" \"Item E\" | Result: " + rpushResult);

             /**
             * Check list
              *
             * Command: lrange bigboxlist 0 -1
             * Result:
             *          1) "Item A"
             *          2) "Item B"
             *          3) "Item C"
             *          4) "Item D"
             *          5) "Item E"
             */
            List<String> lrangeResult = jedis.lrange("bigboxlist", 0, -1);

            System.out.println("Command: lrange bigboxlist 0 -1 | Result: " + lrangeResult.toString());

            /**
             * Set value at index 0
             *
             * Command: lset bigboxlist 0 "Changed item AAAA"
             * Result: OK
             */
            String lsetResult = jedis.lset("bigboxlist", 0, "Changed item AAAA");

            System.out.println("Command: lset bigboxlist 0 \"Changed item AAAA\" | Result: " + lsetResult);

            /**
             * Set value at index 2 of list
             *
             * Command: lset bigboxlist 2 "Changed item CCCC"
             * Result: OK
             */
            lsetResult = jedis.lset("bigboxlist", 2, "Changed item CCCC");

            System.out.println("Command: lset bigboxlist 2 \"Changed item CCCC\" | Result: " + lsetResult);

            /**
             * Set value at index -1 of list
             *
             * Command: lset bigboxlist -1 "Changed item EEEE"
             * Result: OK
             */
            lsetResult = jedis.lset("bigboxlist", -1, "Changed item EEEE");

            System.out.println("Command: lset bigboxlist -1 \"Changed item EEEE\" | Result: " + lsetResult);

            /**
             * Check list value
             *
             * Command: lrange bigboxlist 0 -1
             * Result:
             *         1) "Changed item AAAA"
             *         2) "Item B"
             *         3) "Changed item CCCC"
             *         4) "Item D"
             *         5) "Changed item EEEE"
             */
            lrangeResult = jedis.lrange("bigboxlist", 0, -1);

            System.out.println("Command: lrange bigboxlist 0 -1 | Result: " + lrangeResult.toString());

            /**
             * Try to set value at some out of range index
             * error returned
             *
             * Command: lset bigboxlist 200 "Some out of range dummy"
             * Result: (error) ERR index out of range
             */
            try {
                lsetResult = jedis.lset("bigboxlist", 200, "Some out of range dummy");

                System.out.println("Command: lset bigboxlist 200 \"Some out of range dummy\" | Result: " + lsetResult);
            } catch(Exception e) {
                System.out.println("Command: lset bigboxlist 200 \"Some out of range dummy\" | Error: " + e.getMessage());
            }

            /**
             * Try to set value at some out of range index
             * error returned
             *
             * Command: lset bigboxlist -100 "Another out of range dummy"
             * Result: (error) ERR index out of range
             */
            try {
                lsetResult = jedis.lset("bigboxlist", -200, "Another out of range dummy");

                System.out.println("Command: lset bigboxlist -100 \"Another out of range dummy\" | Result: " + lsetResult);
            } catch(Exception e) {
                System.out.println("Command: lset bigboxlist -100 \"Another out of range dummy\" | Error: " + e.getMessage());
            }

            /**
             * Try to use LSET on a non existing list
             *  We get an error
             *
             * Command: lset nonexistinglist 0 "My value 101"
             * Result: (error) ERR no such key
             */
            try {
                lsetResult = jedis.lset("nonexistinglist", 0, "My value 101");

                System.out.println("Command: lset nonexistinglist 0 \"My value 101\" | Result: " + lsetResult);
            } catch(Exception e) {
                System.out.println("Command: lset nonexistinglist 0 \"My value 101\" | Error: " + e.getMessage());
            }

            /**
             * Set some string value
             *
             * Command: set bigboxstr "some string value here"
             * Result: OK
             */
            String setResult = jedis.set("bigboxstr", "some string value here");

            System.out.println("Command: set bigboxstr \"some string value here\" | Result: " + setResult);

            /**
             * Try to use LSET for a string
             * error returned as LSET can only be used on a list
             *
             * Command: lset bigboxstr 0 "use lset for str"
             * Result: (error) WRONGTYPE Operation against a key holding the wrong kind of value
             */
            try {
                lsetResult = jedis.lset("bigboxstr", 0, "use lset for str");

                System.out.println("Command: lset bigboxstr 0 \"use lset for str\" | Result: " + lsetResult);
            } catch(Exception e) {
                System.out.println("Command: lset bigboxstr 0 \"use lset for str\" | Error: " + e.getMessage());
            }

        }

        jedisPool.close();
    }
}

Output:

Command: rpush bigboxlist "Item A" "Item B" "Item C" "Item D" "Item E" | Result: 5
Command: lrange bigboxlist 0 -1 | Result: [Item A, Item B, Item C, Item D, Item E]

Command: lset bigboxlist 0 "Changed item AAAA" | Result: OK
Command: lset bigboxlist 2 "Changed item CCCC" | Result: OK
Command: lset bigboxlist -1 "Changed item EEEE" | Result: OK

Command: lrange bigboxlist 0 -1 | Result: [Changed item AAAA, Item B, Changed item CCCC, Item D, Changed item EEEE]

Command: lset bigboxlist 200 "Some out of range dummy" | Error: ERR index out of range
Command: lset bigboxlist -100 "Another out of range dummy" | Error: ERR index out of range
Command: lset nonexistinglist 0 "My value 101" | Error: ERR no such key

Command: set bigboxstr "some string value here" | Result: OK
Command: lset bigboxstr 0 "use lset for str" | Error: WRONGTYPE Operation against a key holding the wrong kind of value

Notes

Use method “lset” from Jedis package.
The signature of the method is-
public String lset(final String key, final long index, final String value)

// Redis LSET command examples in C#

using StackExchange.Redis;

namespace Lset
{
    internal class Program
    {
        static void Main(string[] args)
        {
            ConnectionMultiplexer redis = ConnectionMultiplexer.Connect("localhost");
            IDatabase rdb = redis.GetDatabase();

            /**
             * Push some value to list
             *
             * Command: rpush bigboxlist "Item A" "Item B" "Item C" "Item D" "Item E"
             * Result: (integer) 5
             */
            long rpushResult = rdb.ListRightPush("bigboxlist", new RedisValue[] { "Item A", "Item B", "Item C", "Item D", "Item E" });

            Console.WriteLine("Command: rpush bigboxlist \"Item A\" \"Item B\" \"Item C\" \"Item D\" \"Item E\" | Result: " + rpushResult);

            /**
            * Check list
             *
            * Command: lrange bigboxlist 0 -1
            * Result:
            *          1) "Item A"
            *          2) "Item B"
            *          3) "Item C"
            *          4) "Item D"
            *          5) "Item E"
            */
            RedisValue[] lrangeResult = rdb.ListRange("bigboxlist", 0, -1);
            Console.WriteLine("Command: lrange bigboxlist 0 -1 | Result: " + string.Join(", ", lrangeResult));

            /**
             * Set value at index 0
             *
             * Command: lset bigboxlist 0 "Changed item AAAA"
             * Result: OK
             */
            rdb.ListSetByIndex("bigboxlist", 0, "Changed item AAAA");
            Console.WriteLine("Command: lset bigboxlist 0 \"Changed item AAAA\"");

            /**
             * Set value at index 2 of list
             *
             * Command: lset bigboxlist 2 "Changed item CCCC"
             * Result: OK
             */
            rdb.ListSetByIndex("bigboxlist", 2, "Changed item CCCC");

            Console.WriteLine("Command: lset bigboxlist 2 \"Changed item CCCC\"");

            /**
             * Set value at index -1 of list
             *
             * Command: lset bigboxlist -1 "Changed item EEEE"
             * Result: OK
             */
            rdb.ListSetByIndex("bigboxlist", -1, "Changed item EEEE");

            Console.WriteLine("Command: lset bigboxlist -1 \"Changed item EEEE\"");

            /**
             * Check list value
             *
             * Command: lrange bigboxlist 0 -1
             * Result:
             *         1) "Changed item AAAA"
             *         2) "Item B"
             *         3) "Changed item CCCC"
             *         4) "Item D"
             *         5) "Changed item EEEE"
             */
            lrangeResult = rdb.ListRange("bigboxlist", 0, -1);

            Console.WriteLine("Command: lrange bigboxlist 0 -1 | Result: " + string.Join(", ", lrangeResult));

            /**
             * Try to set value at some out of range index
             * error returned
             *
             * Command: lset bigboxlist 200 "Some out of range dummy"
             * Result: (error) ERR index out of range
             */
            try
            {
                rdb.ListSetByIndex("bigboxlist", 200, "Some out of range dummy");

                Console.WriteLine("Command: lset bigboxlist 200 \"Some out of range dummy\"");
            }
            catch (Exception e)
            {
                Console.WriteLine("Command: lset bigboxlist 200 \"Some out of range dummy\" | Error: " + e.Message);
            }

            /**
             * Try to set value at some out of range index
             * error returned
             *
             * Command: lset bigboxlist -100 "Another out of range dummy"
             * Result: (error) ERR index out of range
             */
            try
            {
                rdb.ListSetByIndex("bigboxlist", -200, "Another out of range dummy");

                Console.WriteLine("Command: lset bigboxlist -100 \"Another out of range dummy\"");
            }
            catch (Exception e)
            {
                Console.WriteLine("Command: lset bigboxlist -100 \"Another out of range dummy\" | Error: " + e.Message);
            }

            /**
             * Try to use LSET on a non existing list
             *  We get an error
             *
             * Command: lset nonexistinglist 0 "My value 101"
             * Result: (error) ERR no such key
             */
            try
            {
                rdb.ListSetByIndex("nonexistinglist", 0, "My value 101");

                Console.WriteLine("Command: lset nonexistinglist 0 \"My value 101\"");
            }
            catch (Exception e)
            {
                Console.WriteLine("Command: lset nonexistinglist 0 \"My value 101\" | Error: " + e.Message);
            }

            /**
             * Set some string value
             *
             * Command: set bigboxstr "some string value here"
             * Result: OK
             */
            bool setResult = rdb.StringSet("bigboxstr", "some string value here");
            Console.WriteLine("Command: set bigboxstr \"some string value here\" | Result: " + setResult);

            /**
             * Try to use LSET for a string
             * error returned as LSET can only be used on a list
             *
             * Command: lset bigboxstr 0 "use lset for str"
             * Result: (error) WRONGTYPE Operation against a key holding the wrong kind of value
             */
            try
            {
                rdb.ListSetByIndex("bigboxstr", 0, "use lset for str");

                Console.WriteLine("Command: lset bigboxstr 0 \"use lset for str\"");
            }
            catch (Exception e)
            {
                Console.WriteLine("Command: lset bigboxstr 0 \"use lset for str\" | Error: " + e.Message);
            }
        }
    }
}

Output:

Command: rpush bigboxlist "Item A" "Item B" "Item C" "Item D" "Item E" | Result: 5
Command: lrange bigboxlist 0 -1 | Result: Item A, Item B, Item C, Item D, Item E

Command: lset bigboxlist 0 "Changed item AAAA"
Command: lset bigboxlist 2 "Changed item CCCC"
Command: lset bigboxlist -1 "Changed item EEEE"

Command: lrange bigboxlist 0 -1 | Result: Changed item AAAA, Item B, Changed item CCCC, Item D, Changed item EEEE

Command: lset bigboxlist 200 "Some out of range dummy" | Error: ERR index out of range
Command: lset bigboxlist -100 "Another out of range dummy" | Error: ERR index out of range

Command: lset nonexistinglist 0 "My value 101" | Error: ERR no such key

Command: set bigboxstr "some string value here" | Result: True
Command: lset bigboxstr 0 "use lset for str" | Error: WRONGTYPE Operation against a key holding the wrong kind of value

Notes

Use the method “ListSetByIndex” from StackExchange.Redis.
Signature of the method is-
void ListSetByIndex(RedisKey key, long index, RedisValue value, CommandFlags flags = CommandFlags.None)

<?php
// Redis LSET command example in PHP

require 'vendor/autoload.php';

// Connect to Redis
$redisClient = new Predis\Client([
    'scheme' => 'tcp',
    'host' => 'localhost',
    'port' => 6379,
]);


/**
 * Push some value to list
 *
 * Command: rpush bigboxlist "Item A" "Item B" "Item C" "Item D" "Item E"
 * Result: (integer) 5
 */
$commandResult = $redisClient->rpush("bigboxlist", ["Item A", "Item B", "Item C", "Item D", "Item E"]);

echo "Command: rpush bigboxlist \"Item A\" \"Item B\" \"Item C\" \"Item D\" \"Item E\" | Result: " . $commandResult . "\n";

/**
 * Check list
 *
 * Command: lrange bigboxlist 0 -1
 * Result:
 *          1) "Item A"
 *          2) "Item B"
 *          3) "Item C"
 *          4) "Item D"
 *          5) "Item E"
 */
$commandResult = $redisClient->lrange("bigboxlist", 0, -1);

echo "Command: lrange bigboxlist 0 -1 | Result: ";
print_r($commandResult);

/**
 * Set value at index 0
 *
 * Command: lset bigboxlist 0 "Changed item AAAA"
 * Result: OK
 */
$commandResult = $redisClient->lset("bigboxlist", 0, "Changed item AAAA");

echo "Command: lset bigboxlist 0 \"Changed item AAAA\" | Result: " . $commandResult . "\n";

/**
 * Set value at index 2 of list
 *
 * Command: lset bigboxlist 2 "Changed item CCCC"
 * Result: OK
 */
$commandResult = $redisClient->lset("bigboxlist", 2, "Changed item CCCC");

echo "Command: lset bigboxlist 2 \"Changed item CCCC\" | Result: " . $commandResult . "\n";

/**
 * Set value at index -1 of list
 *
 * Command: lset bigboxlist -1 "Changed item EEEE"
 * Result: OK
 */
$commandResult = $redisClient->lset("bigboxlist", -1, "Changed item EEEE");

echo "Command: lset bigboxlist -1 \"Changed item EEEE\" | Result: " . $commandResult . "\n";

/**
 * Check list value
 *
 * Command: lrange bigboxlist 0 -1
 * Result:
 *         1) "Changed item AAAA"
 *         2) "Item B"
 *         3) "Changed item CCCC"
 *         4) "Item D"
 *         5) "Changed item EEEE"
 */
$commandResult = $redisClient->lrange("bigboxlist", 0, -1);

echo "Command: lrange bigboxlist 0 -1 | Result: ";
print_r($commandResult);

/**
 * Try to set value at some out of range index
 * error returned
 *
 * Command: lset bigboxlist 200 "Some out of range dummy"
 * Result: (error) ERR index out of range
 */
try {
    $commandResult = $redisClient->lset("bigboxlist", 200, "Some out of range dummy");

    echo "Command: lset bigboxlist 200 \"Some out of range dummy\" | Result: " . $commandResult . "\n";
} catch (\Exception $e) {
    echo "Command: lset bigboxlist 200 \"Some out of range dummy\" | Error: " . $e->getMessage() . "\n";
}

/**
 * Try to set value at some out of range index
 * error returned
 *
 * Command: lset bigboxlist -100 "Another out of range dummy"
 * Result: (error) ERR index out of range
 */
try {
    $commandResult = $redisClient->lset("bigboxlist", -200, "Another out of range dummy");

    echo "Command: lset bigboxlist -100 \"Another out of range dummy\" | Result: " . $commandResult . "\n";
} catch (\Exception $e) {
    echo "Command: lset bigboxlist -100 \"Another out of range dummy\" | Error: " . $e->getMessage() . "\n";
}

/**
 * Try to use LSET on a non existing list
 *  We get an error
 *
 * Command: lset nonexistinglist 0 "My value 101"
 * Result: (error) ERR no such key
 */
try {
    $commandResult = $redisClient->lset("nonexistinglist", 0, "My value 101");

    echo "Command: lset nonexistinglist 0 \"My value 101\" | Result: " . $commandResult . "\n";
} catch (\Exception $e) {
    echo "Command: lset nonexistinglist 0 \"My value 101\" | Error: " . $e->getMessage() . "\n";
}

/**
 * Set some string value
 *
 * Command: set bigboxstr "some string value here"
 * Result: OK
 */
$commandResult = $redisClient->set("bigboxstr", "some string value here");

echo "Command: set bigboxstr \"some string value here\" | Result: " . $commandResult . "\n";

/**
 * Try to use LSET for a string
 * error returned as LSET can only be used on a list
 *
 * Command: lset bigboxstr 0 "use lset for str"
 * Result: (error) WRONGTYPE Operation against a key holding the wrong kind of value
 */
try {
    $commandResult = $redisClient->lset("bigboxstr", 0, "use lset for str");

    echo "Command: lset bigboxstr 0 \"use lset for str\" | Result: " . $commandResult . "\n";
} catch (\Exception $e) {
    echo "Command: lset bigboxstr 0 \"use lset for str\" | Error: " . $e->getMessage() . "\n";
}

Output:

Command: rpush bigboxlist "Item A" "Item B" "Item C" "Item D" "Item E" | Result: 5
Command: lrange bigboxlist 0 -1 | Result: Array
(
    [0] => Item A
    [1] => Item B
    [2] => Item C
    [3] => Item D
    [4] => Item E
)

Command: lset bigboxlist 0 "Changed item AAAA" | Result: OK
Command: lset bigboxlist 2 "Changed item CCCC" | Result: OK
Command: lset bigboxlist -1 "Changed item EEEE" | Result: OK

Command: lrange bigboxlist 0 -1 | Result: Array
(
    [0] => Changed item AAAA
    [1] => Item B
    [2] => Changed item CCCC
    [3] => Item D
    [4] => Changed item EEEE
)

Command: lset bigboxlist 200 "Some out of range dummy" | Error: ERR index out of range
Command: lset bigboxlist -100 "Another out of range dummy" | Error: ERR index out of range

Command: lset nonexistinglist 0 "My value 101" | Error: ERR no such key

Command: set bigboxstr "some string value here" | Result: OK
Command: lset bigboxstr 0 "use lset for str" | Error: WRONGTYPE Operation against a key holding the wrong kind of value

Notes

Use the method “lset” of predis.

Signature of the method is-
lset(string $key, int $index, string $value): mixed

# Redis LSET command example in Python

import redis
import time

# Create Redis client
redisClient = redis.Redis(host='localhost', port=6379,
                          username='default', password='',
                          decode_responses=True)


# Push some value to list
# Command: rpush bigboxlist "Item A" "Item B" "Item C" "Item D" "Item E"
# Result: (integer) 5
commandResult = redisClient.rpush("bigboxlist", "Item A", "Item B", "Item C", "Item D", "Item E")

print("Command: rpush bigboxlist \"Item A\" \"Item B\" \"Item C\" \"Item D\" \"Item E\" | Result: {}".format(commandResult))

# Check list
# Command: lrange bigboxlist 0 -1
# Result:
#          1) "Item A"
#          2) "Item B"
#          3) "Item C"
#          4) "Item D"
#          5) "Item E"
commandResult = redisClient.lrange("bigboxlist", 0, -1)

print("Command: lrange bigboxlist 0 -1 | Result: {}".format(commandResult))

# Set value at index 0
# Command: lset bigboxlist 0 "Changed item AAAA"
# Result: OK
commandResult = redisClient.lset("bigboxlist", 0, "Changed item AAAA")

print("Command: lset bigboxlist 0 \"Changed item AAAA\" | Result: {}".format(commandResult))

# Set value at index 2 of list
# Command: lset bigboxlist 2 "Changed item CCCC"
# Result: OK
commandResult = redisClient.lset("bigboxlist", 2, "Changed item CCCC")

print("Command: lset bigboxlist 2 \"Changed item CCCC\" | Result: {}".format(commandResult))

# Set value at index -1 of list
# Command: lset bigboxlist -1 "Changed item EEEE"
# Result: OK
commandResult = redisClient.lset("bigboxlist", -1, "Changed item EEEE")

print("Command: lset bigboxlist -1 \"Changed item EEEE\" | Result: {}".format(commandResult))

# Check list value
# Command: lrange bigboxlist 0 -1
# Result:
#         1) "Changed item AAAA"
#         2) "Item B"
#         3) "Changed item CCCC"
#         4) "Item D"
#         5) "Changed item EEEE"
commandResult = redisClient.lrange("bigboxlist", 0, -1)

print("Command: lrange bigboxlist 0 -1 | Result: {}".format(commandResult))

# Try to set value at some out of range index
# error returned
# Command: lset bigboxlist 200 "Some out of range dummy"
# Result: (error) ERR index out of range
try:
    commandResult = redisClient.lset("bigboxlist", 200, "Some out of range dummy")

    print("Command: lset bigboxlist 200 \"Some out of range dummy\" | Result: {}".format(commandResult))
except Exception as error:
    print("Command: lset bigboxlist 200 \"Some out of range dummy\" | Error: ", error)

# Try to set value at some out of range index
# error returned
# Command: lset bigboxlist -100 "Another out of range dummy"
# Result: (error) ERR index out of range
try:
    commandResult = redisClient.lset("bigboxlist", -200, "Another out of range dummy")

    print("Command: lset bigboxlist -100 \"Another out of range dummy\" | Result: {}".format(commandResult))
except Exception as error:
    print("Command: lset bigboxlist -100 \"Another out of range dummy\" | Error: ", error)

# Try to use LSET on a non existing list
#  We get an error
# Command: lset nonexistinglist 0 "My value 101"
# Result: (error) ERR no such key
try:
    commandResult = redisClient.lset("nonexistinglist", 0, "My value 101")

    print("Command: lset nonexistinglist 0 \"My value 101\" | Result: {}".format(commandResult))
except Exception as error:
    print("Command: lset nonexistinglist 0 \"My value 101\" | Error: ", error)

# Set some string value
# Command: set bigboxstr "some string value here"
# Result: OK
commandResult = redisClient.set("bigboxstr", "some string value here")

print("Command: set bigboxstr \"some string value here\" | Result: {}".format(commandResult))

# Try to use LSET for a string
# error returned as LSET can only be used on a list
# Command: lset bigboxstr 0 "use lset for str"
# Result: (error) WRONGTYPE Operation against a key holding the wrong kind of value
try:
    commandResult = redisClient.lset("bigboxstr", 0, "use lset for str")

    print("Command: lset bigboxstr 0 \"use lset for str\" | Result: {}".format(commandResult))
except Exception as error:
    print("Command: lset bigboxstr 0 \"use lset for str\" | Error: ", error)

Output:

Command: rpush bigboxlist "Item A" "Item B" "Item C" "Item D" "Item E" | Result: 5
Command: lrange bigboxlist 0 -1 | Result: ['Item A', 'Item B', 'Item C', 'Item D', 'Item E']

Command: lset bigboxlist 0 "Changed item AAAA" | Result: True
Command: lset bigboxlist 2 "Changed item CCCC" | Result: True
Command: lset bigboxlist -1 "Changed item EEEE" | Result: True

Command: lrange bigboxlist 0 -1 | Result: ['Changed item AAAA', 'Item B', 'Changed item CCCC', 'Item D', 'Changed item EEEE']       

Command: lset bigboxlist 200 "Some out of range dummy" | Error:  index out of range
Command: lset bigboxlist -100 "Another out of range dummy" | Error:  index out of range

Command: lset nonexistinglist 0 "My value 101" | Error:  no such key

Command: set bigboxstr "some string value here" | Result: True
Command: lset bigboxstr 0 "use lset for str" | Error:  WRONGTYPE Operation against a key holding the wrong kind of value

Notes

Use method “lset” from redis-py.
Signature of the method is –
def lset(self, name: str, index: int, value: str) -> Union[Awaitable[str], str]

# Redis LSET command example in Ruby

require 'redis'

redis = Redis.new(host: "localhost", port: 6379)


# Push some value to list
# Command: rpush bigboxlist "Item A" "Item B" "Item C" "Item D" "Item E"
# Result: (integer) 5
commandResult = redis.rpush("bigboxlist", ["Item A", "Item B", "Item C", "Item D", "Item E"])

print("Command: rpush bigboxlist \"Item A\" \"Item B\" \"Item C\" \"Item D\" \"Item E\" | Result: ", commandResult, "\n")

# Check list
# Command: lrange bigboxlist 0 -1
# Result:
#          1) "Item A"
#          2) "Item B"
#          3) "Item C"
#          4) "Item D"
#          5) "Item E"
commandResult = redis.lrange("bigboxlist", 0, -1)

print("Command: lrange bigboxlist 0 -1 | Result: ", commandResult, "\n")

# Set value at index 0
# Command: lset bigboxlist 0 "Changed item AAAA"
# Result: OK
commandResult = redis.lset("bigboxlist", 0, "Changed item AAAA")

print("Command: lset bigboxlist 0 \"Changed item AAAA\" | Result: ", commandResult, "\n")

# Set value at index 2 of list
# Command: lset bigboxlist 2 "Changed item CCCC"
# Result: OK
commandResult = redis.lset("bigboxlist", 2, "Changed item CCCC")

print("Command: lset bigboxlist 2 \"Changed item CCCC\" | Result: ", commandResult, "\n")

# Set value at index -1 of list
# Command: lset bigboxlist -1 "Changed item EEEE"
# Result: OK
commandResult = redis.lset("bigboxlist", -1, "Changed item EEEE")

print("Command: lset bigboxlist -1 \"Changed item EEEE\" | Result: ", commandResult, "\n")

# Check list value
# Command: lrange bigboxlist 0 -1
# Result:
#         1) "Changed item AAAA"
#         2) "Item B"
#         3) "Changed item CCCC"
#         4) "Item D"
#         5) "Changed item EEEE"
commandResult = redis.lrange("bigboxlist", 0, -1)

print("Command: lrange bigboxlist 0 -1 | Result: ", commandResult, "\n")

# Try to set value at some out of range index
# error returned
# Command: lset bigboxlist 200 "Some out of range dummy"
# Result: (error) ERR index out of range
begin
    commandResult = redis.lset("bigboxlist", 200, "Some out of range dummy")

    print("Command: lset bigboxlist 200 \"Some out of range dummy\" | Result: ", commandResult, "\n")
rescue => e
    print("Command: lset bigboxlist 200 \"Some out of range dummy\" | Error: ", e, "\n")
end

# Try to set value at some out of range index
# error returned
# Command: lset bigboxlist -100 "Another out of range dummy"
# Result: (error) ERR index out of range
begin
    commandResult = redis.lset("bigboxlist", -200, "Another out of range dummy")

    print("Command: lset bigboxlist -100 \"Another out of range dummy\" | Result: ", commandResult, "\n")
rescue => e
    print("Command: lset bigboxlist -100 \"Another out of range dummy\" | Error: ", e, "\n")
end

# Try to use LSET on a non existing list
#  We get an error
# Command: lset nonexistinglist 0 "My value 101"
# Result: (error) ERR no such key
begin
    commandResult = redis.lset("nonexistinglist", 0, "My value 101")

    print("Command: lset nonexistinglist 0 \"My value 101\" | Result: ", commandResult, "\n")
rescue => e
    print("Command: lset nonexistinglist 0 \"My value 101\" | Error: ", e, "\n")
end

# Set some string value
# Command: set bigboxstr "some string value here"
# Result: OK
commandResult = redis.set("bigboxstr", "some string value here")

print("Command: set bigboxstr \"some string value here\" | Result: ", commandResult, "\n")

# Try to use LSET for a string
# error returned as LSET can only be used on a list
# Command: lset bigboxstr 0 "use lset for str"
# Result: (error) WRONGTYPE Operation against a key holding the wrong kind of value
begin
    commandResult = redis.lset("bigboxstr", 0, "use lset for str")

    print("Command: lset bigboxstr 0 \"use lset for str\" | Result: ", commandResult, "\n")
rescue => e
    print("Command: lset bigboxstr 0 \"use lset for str\" | Error: ", e, "\n")
end

Output:

Command: rpush bigboxlist "Item A" "Item B" "Item C" "Item D" "Item E" | Result: 5
Command: lrange bigboxlist 0 -1 | Result: ["Item A", "Item B", "Item C", "Item D", "Item E"]

Command: lset bigboxlist 0 "Changed item AAAA" | Result: OK
Command: lset bigboxlist 2 "Changed item CCCC" | Result: OK
Command: lset bigboxlist -1 "Changed item EEEE" | Result: OK

Command: lrange bigboxlist 0 -1 | Result: ["Changed item AAAA", "Item B", "Changed item CCCC", "Item D", "Changed item EEEE"]

Command: lset bigboxlist 200 "Some out of range dummy" | Error: ERR index out of range
Command: lset bigboxlist -100 "Another out of range dummy" | Error: ERR index out of range

Command: lset nonexistinglist 0 "My value 101" | Error: ERR no such key

Command: set bigboxstr "some string value here" | Result: OK
Command: lset bigboxstr 0 "use lset for str" | Error: WRONGTYPE Operation against a key holding the wrong kind of value

Notes

Use method “lset” from the redis-rb.
Signature of the method is-

# @param [String] key
# @param [Integer] index
# @param [String] value
# @return [String] `OK`
def lset(key, index, value)

Source Code

Use the following links to get the source code used in this article-

Source Code of	Source Code Link
Command Examples	GitHub
Golang Implementation	GitHub
NodeJS Implementation	GitHub
Java Implementation	GitHub
C# Implementation	GitHub
PHP Implementation	GitHub
Python Implementation	GitHub
Ruby Implementation	GitHub

Related Commands

Command	Details
LRANGE	Command Details
LPUSH	Command Details
RPUSH	Command Details

Summary

Signature

Usage

Arguments

Return Value

Examples

Code Implementations

Source Code

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