LINSERT - Upstash Documentation

Use LINSERT to insert an element immediately before or after another element of a list.

The pivot is matched by value, and only its first occurrence starting from the head is used. The reply is the new length of the list, 0 when the key does not exist, and -1 when the pivot value was not found, which is how you tell a failed insert from a successful one.

Finding the pivot means scanning the list, so this is a linear operation; on long lists it is worth keeping an index elsewhere or using a sorted set instead.

Syntax#

LINSERT <key> (BEFORE | AFTER) <pivot> <element>

Arguments#

Argument	Required	Repeatable	Description
`<key>`	Yes	No	Redis key targeted by the command.
`(BEFORE \| AFTER)`	Yes	No	Where to place the new element relative to the pivot: `BEFORE` or `AFTER`.
`<pivot>`	Yes	No	Existing element to insert next to.
`<element>`	Yes	No	Element to insert.

Response#

The reply reports the result of the operation. Error replies have the same shape in RESP2 and RESP3 and are surfaced as exceptions by the SDKs below.

Protocol	Reply
RESP2	Integer: the list length after insertion, `-1` if the pivot was not found, `0` if the key does not exist
RESP3	Integer: the list length after insertion, `-1` if the pivot was not found, `0` if the key does not exist

Note

Client libraries often decode bulk strings, maps, sets, and numeric strings into language-native values. The table describes the Redis wire reply.

Examples#

TCP examples use the TLS REDIS_URL from the Upstash console. REST examples use UPSTASH_REDIS_REST_URL and UPSTASH_REDIS_REST_TOKEN.

Redis CLI

LINSERT my-key BEFORE pivot element

@upstash/redis

import { Redis } from "@upstash/redis";const redis = Redis.fromEnv();await redis.rpush("key", "a", "b", "c");await redis.linsert("key", "before", "b", "x");

upstash_redis

from upstash_redis import Redisredis = Redis.from_env()result = redis.linsert("my-key", "BEFORE", "pivot", "element")print(result)

ioredis

import Redis from "ioredis";const redis = new Redis(process.env.REDIS_URL!);const result = await redis.linsert("my-key", "BEFORE", "pivot", "element");console.log(result);

node-redis

import { createClient } from "redis";const client = await createClient({ url: process.env.REDIS_URL })  .on("error", console.error)  .connect();const result = await client.lInsert("my-key", "BEFORE", "pivot", "element");console.log(result);

redis-py

import osimport redisclient = redis.from_url(os.environ["REDIS_URL"])result = client.linsert("my-key", "BEFORE", "pivot", "element")print(result)

go-redis

package mainimport (    "context"    "fmt"    "os"    "github.com/redis/go-redis/v9")func main() {    opts, err := redis.ParseURL(os.Getenv("REDIS_URL"))    if err != nil {        panic(err)    }    client := redis.NewClient(opts)    result, err := client.LInsertBefore(context.Background(), "my-key", "pivot", "element").Result()    if err != nil {        panic(err)    }    fmt.Println(result)}

jedis

import java.net.URI;import redis.clients.jedis.Jedis;try (Jedis jedis = new Jedis(new URI(System.getenv("REDIS_URL")))) {  Object result = jedis.linsert("my-key", redis.clients.jedis.args.ListPosition.BEFORE, "pivot", "element");  System.out.println(result);}

redis-rs

use redis::TypedCommands;fn main() -> redis::RedisResult<()> {    let url = std::env::var("REDIS_URL").expect("REDIS_URL is not set");    let client = redis::Client::open(url)?;    let mut connection = client.get_connection()?;    let result = connection.linsert_before("my-key", "pivot", "element")?;    println!("{result:?}");    Ok(())}