Redis Command: LLEN

// Redis LLEN 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() {

	// Create list and push element. We are pushing 5 elements to the list
	// Command: rpush bigboxlist one two three four five
	// Result: (integer) 5
	pushResult, err := rdb.RPush(ctx, "bigboxlist", "one", "two", "three", "four", "five").Result()

	if err != nil {
		fmt.Println("Command: rpush bigboxlist one two three four five | Error: " + err.Error())
	}

	fmt.Printf("Command: rpush bigboxlist one two three four five | Result: %v\n", pushResult)

	// Check length of the list
	// Command: llen bigboxlist
	// Result: (integer) 5
	listLength, err := rdb.LLen(ctx, "bigboxlist").Result()

	if err != nil {
		fmt.Println("Command: llen bigboxlist | Error: " + err.Error())
	}

	fmt.Printf("Command: llen bigboxlist | Result: %v\n", listLength)

	// Use LLEN for an non existing key
	// It returns Zero(0)
	// Command: llen nonexistingkey
	// Result: (integer) 0
	listLength, err = rdb.LLen(ctx, "nonexistingkey").Result()

	if err != nil {
		fmt.Println("Command: llen nonexistingkey | Error: " + err.Error())
	}

	fmt.Printf("Command: llen nonexistingkey | Result: %v\n", listLength)

	// Set a string key/value
	// Command: set somestrkey "my string value here for test"
	// Result: OK
	setResult, err := rdb.Set(ctx, "somestrkey", "my string value here for test", 0).Result()

	if err != nil {
		fmt.Println("Command: set somestrkey \"my string value here for test\" | Error: " + err.Error())
	}

	fmt.Println("Command: set somestrkey \"my string value here for test\" | Result: " + setResult)

	// Try to use LLEN command for string type key
	// It returns error which indicates, the type of key is wrong
	// Command: llen somestrkey
	// Result: (error) WRONGTYPE Operation against a key holding the wrong kind of value
	listLength, err = rdb.LLen(ctx, "somestrkey").Result()

	if err != nil {
		fmt.Println("Command: llen somestrkey | Error: " + err.Error())
	}

	fmt.Printf("Command: llen somestrkey | Result: %v\n", listLength)

}

Output:

Command: rpush bigboxlist one two three four five | Result: 5

Command: llen bigboxlist | Result: 5

Command: llen nonexistingkey | Result: 0

Command: set somestrkey "my string value here for test" | Result: OK
Command: llen somestrkey | Error: WRONGTYPE Operation against a key holding the wrong kind of value
Command: llen somestrkey | Result: 0

// Redis LLEN command example in JavaScript(NodeJS)

import { createClient } from "redis";

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

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

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

/**
 * Create list and push element. We are pushing 5 elements to the list
 *
 * Command: rpush bigboxlist one two three four five
 * Result: (integer) 5
 */
let commandResult = await redisClient.rPush("bigboxlist", [
  "one",
  "two",
  "three",
  "four",
  "five"
]);

console.log(
  "Command: rpush bigboxlist one two three four five | Result: " + commandResult
);

/**
 * Check length of the list
 *
 * Command: llen bigboxlist
 * Result: (integer) 5
 */
commandResult = await redisClient.lLen("bigboxlist");

console.log("Command: llen bigboxlist | Result: " + commandResult);

/**
 * Use LLEN for an non existing key
 * It returns Zero(0)
 *
 * Command: llen nonexistingkey
 * Result: (integer) 0
 */
commandResult = await redisClient.lLen("nonexistingkey");

console.log("Command: llen nonexistingkey | Result: " + commandResult);

/**
 * Set a string key/value
 *
 * Command: set somestrkey "my string value here for test"
 * Result: OK
 */
commandResult = await redisClient.set("somestrkey", "my string value here for test");

console.log(
  'Command: set somestrkey "my string value here for test" | Result: ' +
    commandResult
);

/**
 * Try to use LLEN command for string type key
 * It returns error which indicates, the type of key is wrong
 *
 * Command: llen somestrkey
 * Result: (error) WRONGTYPE Operation against a key holding the wrong kind of value
 */
try {
  commandResult = await redisClient.lLen("somestrkey");

  console.log("Command: llen somestrkey | Result: " + commandResult);
} catch (e) {
  console.log("Command: llen somestrkey | Error: ", e);
}

process.exit(0);

Output:

Command: rpush bigboxlist one two three four five | Result: 5

Command: llen bigboxlist | Result: 5

Command: llen nonexistingkey | Result: 0

Command: set somestrkey "my string value here for test" | Result: OK
Command: llen somestrkey | Error:  [ErrorReply: WRONGTYPE Operation against a key holding the wrong kind of value]

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

public class Llen {

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

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

            /**
             * Create list and push element. We are pushing 5 elements to the list
             *
             * Command: rpush bigboxlist one two three four five
             * Result: (integer) 5
             */
            long pushResult = jedis.rpush("bigboxlist", "one", "two", "three", "four", "five");

            System.out.println("Command: rpush bigboxlist one two three four five | Result: " + pushResult);

            /**
             * Check length of the list
             *
             * Command: llen bigboxlist
             * Result: (integer) 5
             */
            long listLength = jedis.llen("bigboxlist");

            System.out.println("Command: llen bigboxlist | Result: " + listLength);

            /**
             * Use LLEN for an non existing key
             * It returns Zero(0)
             *
             * Command: llen nonexistingkey
             * Result: (integer) 0
             */
            listLength = jedis.llen("nonexistingkey");

            System.out.println("Command: llen nonexistingkey | Result: " + listLength);

            /**
             * Set a string key/value
             *
             * Command: set somestrkey "my string value here for test"
             * Result: OK
             */
            String setResult = jedis.set("somestrkey", "my string value here for test");

            System.out.println("Command: set somestrkey \"my string value here for test\" | Result: " + setResult);

            /**
             * Try to use LLEN command for string type key
             * It returns error which indicates, the type of key is wrong
             *
             * Command: llen somestrkey
             * Result: (error) WRONGTYPE Operation against a key holding the wrong kind of value
             */
            try {
                listLength = jedis.llen("somestrkey");

                System.out.println("Command: llen somestrkey | Result: " + listLength);
            } catch (Exception e) {
                System.out.println("Command: llen somestrkey | Error: " + e.getMessage());
            }
        }

        jedisPool.close();
    }
}

Output:

Command: rpush bigboxlist one two three four five | Result: 5

Command: llen bigboxlist | Result: 5

Command: llen nonexistingkey | Result: 0

Command: set somestrkey "my string value here for test" | Result: OK

Command: llen somestrkey | Error: WRONGTYPE Operation against a key holding the wrong kind of value

// Redis LMOVE command examples in C#

using StackExchange.Redis;

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

            /**
             * Create list and push element. We are pushing 5 elements to the list
             *
             * Command: rpush bigboxlist one two three four five
             * Result: (integer) 5
             */
            long pushResult = rdb.ListRightPush("bigboxlist", new RedisValue[] { "one", "two", "three", "four", "five" });

            Console.WriteLine("Command: rpush bigboxlist one two three four five | Result: " + pushResult);

            /**
             * Check length of the list
             *
             * Command: llen bigboxlist
             * Result: (integer) 5
             */
            long listLength = rdb.ListLength("bigboxlist");

            Console.WriteLine("Command: llen bigboxlist | Result: " + listLength);

            /**
             * Use LLEN for an non existing key
             * It returns Zero(0)
             *
             * Command: llen nonexistingkey
             * Result: (integer) 0
             */
            listLength = rdb.ListLength("nonexistingkey");

            Console.WriteLine("Command: llen nonexistingkey | Result: " + listLength);

            /**
             * Set a string key/value
             *
             * Command: set somestrkey "my string value here for test"
             * Result: OK
             */
            bool setResult = rdb.StringSet("somestrkey", "my string value here for test");

            Console.WriteLine("Command: set somestrkey \"my string value here for test\" | Result: " + setResult);

            /**
             * Try to use LLEN command for string type key
             * It returns error which indicates, the type of key is wrong
             *
             * Command: llen somestrkey
             * Result: (error) WRONGTYPE Operation against a key holding the wrong kind of value
             */
            try
            {
                listLength = rdb.ListLength("somestrkey");

                Console.WriteLine("Command: llen somestrkey | Result: " + listLength);
            }
            catch (Exception e)
            {
                Console.WriteLine("Command: llen somestrkey | Error: " + e.Message);
            }
        }
    }
}

Output:

Command: rpush bigboxlist one two three four five | Result: 5

Command: llen bigboxlist | Result: 5

Command: llen nonexistingkey | Result: 0

Command: set somestrkey "my string value here for test" | Result: True
Command: llen somestrkey | Error: WRONGTYPE Operation against a key holding the wrong kind of value

<?php
// Redis llen command example in PHP

require 'vendor/autoload.php';

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


/**
 * Create list and push element. We are pushing 5 elements to the list
 *
 * Command: rpush bigboxlist one two three four five
 * Result: (integer) 5
 */
$commandResult = $redisClient->rpush("bigboxlist", [
    "one",
    "two",
    "three",
    "four",
    "five"
]);

echo "Command: rpush bigboxlist one two three four five | Result: " . $commandResult . "\n";

/**
 * Check length of the list
 *
 * Command: llen bigboxlist
 * Result: (integer) 5
 */
$commandResult = $redisClient->llen("bigboxlist");

echo "Command: llen bigboxlist | Result: " . $commandResult . "\n";

/**
 * Use LLEN for an non existing key
 * It returns Zero(0)
 *
 * Command: llen nonexistingkey
 * Result: (integer) 0
 */
$commandResult = $redisClient->llen("nonexistingkey");

echo "Command: llen nonexistingkey | Result: " . $commandResult . "\n";

/**
 * Set a string key/value
 *
 * Command: set somestrkey "my string value here for test"
 * Result: OK
 */
$commandResult = $redisClient->set("somestrkey", "my string value here for test");

echo "Command: set somestrkey \"my string value here for test\" | Result: " . $commandResult . "\n";

/**
 * Try to use LLEN command for string type key
 * It returns error which indicates, the type of key is wrong
 *
 * Command: llen somestrkey
 * Result: (error) WRONGTYPE Operation against a key holding the wrong kind of value
 */
try {
    $commandResult = $redisClient->llen("somestrkey");

    echo "Command: llen somestrkey | Result: " . $commandResult . "\n";
} catch (\Exception $e) {
    echo "Command: llen somestrkey | Error: " . $e->getMessage() . "\n";
}

Output:

Command: rpush bigboxlist one two three four five | Result: 5

Command: llen bigboxlist | Result: 5

Command: llen nonexistingkey | Result: 0

Command: set somestrkey "my string value here for test" | Result: OK
Command: llen somestrkey | Error: WRONGTYPE Operation against a key holding the wrong kind of value

# Redis LLEN command example in Python

import redis
import time

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


# Create list and push element. We are pushing 5 elements to the list
# Command: rpush bigboxlist one two three four five
# Result: (integer) 5
commandResult = redisClient.rpush(
    "bigboxlist",
    "one",
    "two",
    "three",
    "four",
    "five"
)

print("Command: rpush bigboxlist one two three four five | Result: {}".format(commandResult))

# Check length of the list
# Command: llen bigboxlist
# Result: (integer) 5
commandResult = redisClient.llen("bigboxlist")

print("Command: llen bigboxlist | Result: {}".format(commandResult))

# Use LLEN for an non existing key
# It returns Zero(0)
# Command: llen nonexistingkey
# Result: (integer) 0
commandResult = redisClient.llen("nonexistingkey")

print("Command: llen nonexistingkey | Result: {}".format(commandResult))

# Set a string key/value
# Command: set somestrkey "my string value here for test"
# Result: OK
commandResult = redisClient.set("somestrkey", "my string value here for test")

print("Command: set somestrkey \"my string value here for test\" | Result: {}".format(commandResult))

# Try to use LLEN command for string type key
# It returns error which indicates, the type of key is wrong
# Command: llen somestrkey
# Result: (error) WRONGTYPE Operation against a key holding the wrong kind of value
try:
    commandResult = redisClient.llen("somestrkey");

    print("Command: llen somestrkey | Result: {}".format(commandResult))
except Exception as error:
    print("Command: llen somestrkey | Error: ", error)

Output:

Command: rpush bigboxlist one two three four five | Result: 5

Command: llen bigboxlist | Result: 5

Command: llen nonexistingkey | Result: 0

Command: set somestrkey "my string value here for test" | Result: True
Command: llen somestrkey | Error:  WRONGTYPE Operation against a key holding the wrong kind of value

# Redis LLEN command example in Ruby

require 'redis'

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


# Create list and push element. We are pushing 5 elements to the list
# Command: rpush bigboxlist one two three four five
# Result: (integer) 5
commandResult = redis.rpush("bigboxlist", [
    "one",
    "two",
    "three",
    "four",
    "five"
])

print("Command: rpush bigboxlist one two three four five | Result: ", commandResult, "\n")

# Check length of the list
# Command: llen bigboxlist
# Result: (integer) 5
commandResult = redis.llen("bigboxlist")

print("Command: llen bigboxlist | Result: ", commandResult, "\n")

# Use LLEN for an non existing key
# It returns Zero(0)
# Command: llen nonexistingkey
# Result: (integer) 0
commandResult = redis.llen("nonexistingkey")

print("Command: llen nonexistingkey | Result: ", commandResult, "\n")

# Set a string key/value
# Command: set somestrkey "my string value here for test"
# Result: OK
commandResult = redis.set("somestrkey", "my string value here for test")

print("Command: set somestrkey \"my string value here for test\" | Result: ", commandResult, "\n")

# Try to use LLEN command for string type key
# It returns error which indicates, the type of key is wrong
# Command: llen somestrkey
# Result: (error) WRONGTYPE Operation against a key holding the wrong kind of value
begin
    commandResult = redis.llen("somestrkey");

    print("Command: llen somestrkey | Result: ", commandResult, "\n")
rescue => e
    print("Command: llen somestrkey | Error: ", e, "\n")
end

Output:

Command: rpush bigboxlist one two three four five | Result: 5

Command: llen bigboxlist | Result: 5

Command: llen nonexistingkey | Result: 0

Command: set somestrkey "my string value here for test" | Result: OK
Command: llen somestrkey | Error: WRONGTYPE Operation against a key holding the wrong kind of value