executing sequent command in redis - node.js

Question

This code doesn't work and I couldn't find out why?
It is always pushing obj right serialized JSON string but it always return with wrong key. In obj id is regularly increasing but key isn't.
var c = redis.createClient(),
obj = {id:0, name:"dudu"},
key="person:";
c.select(0);
c.multi()
.incr("idx:person", function(err, _idx) {
console.log("incr -> #idx: " + _idx);
key += obj.id = _idx;
console.log("After Inc obj: " + JSON.stringify(obj));
})
.set(key, JSON.stringify(obj), function(err, _setResp) {
console.log("set -> #_setResp: " + _setResp);
console.log(JSON.stringify(ihale));
})
.get(key, function(er, _obj) {
console.log("get -> " + key);
if (er) {
res.json(er);
} else {
console.log("Found: " + JSON.stringify(_obj));
res.json(_obj);
}
})
.exec(function(err, replies) {
console.log("MULTI got " + replies.length + " replies");
replies.forEach(function(reply, index) {
console.log("Reply " + index + ": " + reply.toString());
});
});
c.quit();

Answer 1

This worked:
c.INCR("idx:person", function(a,b) {
obj.id = b;
console.dir(obj);
key = "pa:" + b;
c.set(key, JSON.stringify(obj), function(err, _setResp) {
console.log("set -> #_setResp: " + _setResp);
console.log(JSON.stringify(obj));
c.get(key, function(er, _obj) {
console.log("get -> " + key);
if (er) {
res.json(er);
} else {
console.log("Found: " + JSON.stringify(_obj));
res.json(_obj);
}
});
});
});
The way to do this is simple :)
Event driven node is executing every part inside of previous one:
c.INCR("idx:person", function(a,b) {
obj.id = b;
key = "pa:" + b;
c.set(key, JSON.stringify(obj), function(err, _setResp) {
c.get(key, function(er, _obj) {
if (er) {
res.json(er);
} else {
res.json(_obj);
}
});
});
});

Answer 2

In transaction mode command are grouped and passed to Redis . The Exec command execute code you passed . When you pass the key value to a the set command , there is no incremental key value on right of it.
For this kind of use, and if you still want have merged commands in one , script it In Lua:
local keyid = redis.call('INCR', 'idx:person')
local result = redis.call('SET', 'person:'..keyid,ARGV[1])
return 'person:'..keyid
for using it in a redis eval command :
eval "local keyid = redis.call('INCR', 'idx:person'); local result = redis.call('SET', 'person:'..keyid,ARGV[1]);return 'person:'..keyid" 0 "yourJSONObject"
this should work:
client.eval([ "local keyid = redis.call('INCR', 'idx:person'); local result = redis.call('SET', 'person:'..keyid,ARGV[1]);return result", 0,JSON.stringify(obj) ], function (err, res) {
console.log(res); // give the personID
});
You Can also use a Hash instead of a simple key in your example for separate id, name , and json object . Return the hash from the lua script will be like return it from a hset.