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Is it possible to store the array of objects as hash into the Redis?

I’m using Redis with my NodeJS app. I want to store an array of objects (policies) against a key as a hash in Redis. Below is my key and value:-

Key – <tenantid>~<userid> e.g. - tenant123~john123

Value – [{ ptype: 'p', v0: 'admin', v1: '/*', v2: 'GET' }, { ptype: 'p', v0: 'viewer', v1: '/post', v2: 'GET' }]

I’m getting below error :-

err
ReplyError: ERR wrong number of arguments for 'hmset' command
args:Array(2) ["tenant123~john123", "[{ ptype: 'p', v0: 'admin', v1: '/*', v2: 'GET' }, { ptype: 'p', v0: 'viewer', v1: '/post', v2: 'GET' }]"]
code:"ERR"
command:"HMSET"
message:"ERR wrong number of arguments for 'hmset' command"
name:"ReplyError"
stack:"ReplyError: ERR wrong number of arguments for 'hmset' command
    at parseError (/var/task/node_modules/redis-parser/lib/parser.js:179:12)
    at parseType (/var/task/node_modules/redis-parser/lib/parser.js:302:14)"
__proto__:RedisError {constructor: , name: <accessor>}

Below is my NodeJS code where I’m calling hmset() to save the policies into Redis.

module.exports.updateCache = async (hashKey, ttl, obj, logger) => {
    logger.debug('Redis:: Key:', hashKey, ', Obj:', obj);
    return new Promise(function (resolve, reject) {
        myRedisClient.hmset(hashKey, obj, (err, result) => {
            if (err) {
                logger.error(err);
                reject(err);
            } else {
                myRedisClient.expire(hashKey, ttl);
                console.log('result:', result);
                resolve(true);
            }
            console.log('closing redis connection');
            myRedisClient.quit();
        });
    });
}

I tried to debug a lot but could not fix this. Is it not possible to store an array of objects against a hashkey in Redis?

Please assist. Thanks

[Update]

New code:-

module.exports.updateCache = async (hashKey, ttl, obj, logger) => {
    logger.debug('Redis:: Key:', hashKey, ', Obj:', obj);
    return new Promise(function (resolve, reject) {
        myRedisClient.hmset(hashKey, JSON.stringify(obj), (err, result) => {
            if (err) {
                logger.error(err);
                reject(err);
            } else {
                myRedisClient.expire(hashKey, ttl);
                console.log('result:', result);
                resolve(true);
            }
            console.log('closing redis connection');
            myRedisClient.quit();
        });
    });
}

Error:-

err
ReplyError: ERR wrong number of arguments for 'hmset' command
args:Array(2) ["tenant123~john123", "[{"ptype":"p","v0":"admin","v1":"/*","v2":"GET"}]"]
code:"ERR"
command:"HMSET"
message:"ERR wrong number of arguments for 'hmset' command"
name:"ReplyError"
stack:"ReplyError: ERR wrong number of arguments for 'hmset' command
    at parseError (/var/task/node_modules/redis-parser/lib/parser.js:179:12)
    at parseType (/var/task/node_modules/redis-parser/lib/parser.js:302:14)"
Tags:

3

Answers


  1. 0

    It is impossible.

    Redis stores everything in string or in its string representation. you can’t store array of objects or even object(except string) in redis.

    There is no direct means to store objects – it can be done only via serialization and storing resultant byte-array.

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  2. 0

    Redis store strings so you must serialize your JSON object/array to store them, and then deserialize them when you read those keys.

    module.exports.updateCache = async (hashKey, ttl, obj, logger) => {
    logger.debug('Redis:: Key:', hashKey, ', Obj:', obj);
    return new Promise(function (resolve, reject) {
        myRedisClient.hmset(hashKey, { array: JSON.stringify(obj) }, (err, result) => {
            if (err) {
                logger.error(err);
                reject(err);
            } else {
                myRedisClient.expire(hashKey, ttl);
                console.log('result:', result);
                resolve(true);
            }
            console.log('closing redis connection');
            myRedisClient.quit();
        });
    });
}
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  3. 0

    The function hmset is deprecated as of Redis v4.0. Use hset instead.

    Using your newer example, something like

    myRedisClient.hset(hashKey, , 'name', JSON.stringify(obj), (err, result) => ...

    could work. Failures. What was failing, the cause of the error? Pay close attention to the keyname – if this is calling a key by the same name but is a different datatype such as a set, this call would fail.

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