JSON.ARRLEN - Upstash Documentation

Use JSON.ARRLEN to get the number of elements in the arrays a path selects.

Without a path the root value is used. The reply is one length per match, with null for matches that are not arrays, so it doubles as a cheap way to check that a branch of the document really is an array before working on it.

Syntax#

JSON.ARRLEN <key> [path]

Arguments#

Argument	Required	Repeatable	Description
`key`	Yes	No	JSON document key.
`path`	No	No	Path selecting arrays; defaults to the root.

Important points#

Raw TCP examples pass JSON values as valid JSON text. Typed Upstash SDK helpers serialize native objects and values for you.
Paths beginning with $ use JSONPath and can match multiple values, so many JSON commands return an array of per-match results.

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	Array of integer lengths or null values, one per matched path
RESP3	Array of integer lengths or null values, one per matched path

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

JSON.ARRLEN profile $.tags

@upstash/redis

import { Redis } from "@upstash/redis";const redis = Redis.fromEnv();const length = await redis.json.arrlen("key", "$.path.to.array");

upstash_redis

from upstash_redis import Redisredis = Redis.from_env()result = redis.json().arrlen("profile", "$.tags")print(result)

ioredis

import Redis from "ioredis";const redis = new Redis(process.env.REDIS_URL!);const result = await redis.call("JSON.ARRLEN", "profile", "$.tags");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.json.arrLen("profile", { path: "$.tags" });console.log(result);

redis-py

import osimport redisclient = redis.from_url(os.environ["REDIS_URL"])result = client.json().arrlen("profile", "$.tags")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.JSONArrLen(context.Background(), "profile", "$.tags").Result()    if err != nil {        panic(err)    }    fmt.Println(result)}

jedis

import java.net.URI;import redis.clients.jedis.JedisPooled;try (JedisPooled jedis = new JedisPooled(new URI(System.getenv("REDIS_URL")))) {  Object result = jedis.jsonArrLen("profile", new redis.clients.jedis.json.Path("$.tags"));  System.out.println(result);}

redis-rs

use redis::JsonCommands;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: redis::Value = connection.json_arr_len("profile", "$.tags")?;    println!("{result:?}");    Ok(())}