[FIXED] How to send JSON in Redis stream NodeJs

Issue

I am creating one script where I want some dummy data to send to redis server using streams. For that, I am using "ioredis" module for Redis stream. Its working fine when I send simple key value structure i.e {a:"hello",b:"world"}.

But not working for Json array structure.

{
    "name": "abc",
    "ts": 123,
    "lists": [{
        "oil": "1",
        "food": "1,
        "item": "1"
    }]

}

It throws errors like

throw new Error(`Data type of property ${key} is not supported.`);

Solution

Redis Streams don't do JSON. They do allow key-value data to be associated with each event. Note that both the key and the value must be strings.

ioredis does this with variadic arguments for the keys and values. There's an example on the ioredis repo but here's the bit you probably care about:

client.xadd("user-stream", "*", "name", "John", "age", "20")

Node Redis has a different syntax that allows you to pass in a JavaScript object. But, that object must be flat and full of strings. There's an example on GitHub but here's the tl;dr:

client.xAdd('user-stream', '*', { name: "John", age: "20" })

Also, note, that in both cases, the function is async so you can await it if you like.

If you want to store JSON in an event in a Stream in Redis, you'll need to stringify it first:

const data = JSON.stringify({
  "name": "abc",
  "ts": 123,
  "lists": [{
    "oil": "1",
    "food": "1",
    "item": "1"
  }]
})

/* if you use ioredis */
client.xadd("user-stream", "*", "data", data)

/* if you use Node Redis */
client.xAdd('user-stream', '*', { data })

Hope this helps!

Answered By - Guy Royse

Answer Checked By - Pedro (PHPFixing Volunteer)