Redis 4.x Cookbook

How to do it...

The steps for using Lua are as follows:

1. We'll use a Lua script to update a JSON string object in Redis.
2. Open a console and create a Lua script, as follows:

$ mkdir /redis/coding/lua; cd /redis/coding/lua
$ cat updatejson.lua
local id = KEYS[1]
local data = ARGV[1]
local dataSource = cjson.decode(data)
 
local retJson = redis.call('get',  id)
if retJson == false then
    retJson = {}
else
    retJson = cjson.decode(retJson)
end
   
for k,v in pairs(dataSource) do
    retJson[k] = v 
end
redis.call('set', id, cjson.encode(retJson))
return redis.call('get',id)

3. To execute the Lua script, you can use redis-cli to evaluate the script file:

bin/redis-cli --eval updatejson.lua users:id:992452 , '{"name": "Tina", "sex": "female", "grade": "A"}' "{"grade":"A","name":"Tina","sex":"female"}" ...