我有一个lua脚本，我从node.js运行，我的脚本返回一个lua表，其中包含键值对，如{ '1'：15，'2'：35 }.在node中我得到了一个空数组.但是如果我返回arrayName ['1'].它给我正确的值15.我在这里做错了什么.我正在使用node_redis客户端作为node to redis.下面给出了不同的文件.
Lua脚本- groupBy.lua

local db = "";
local table = "students";
local groupBy = "class";
local aggregate = "marks";

local a = {};
local marksGroupedByClass = {};
for i = 1, 4 do
    local dataArr = redis.call("hgetall", db..table..":"..i);
    local dataObj = {};
    for i = 1, #dataArr, 2 do
        dataObj[dataArr[i]] = dataArr[i+1];
    end
    if a[dataObj["class"]] then
        a[dataObj["class"]] = a[dataObj["class"]] + dataObj["marks"]
    else
        a[dataObj["class"]] = dataObj["marks"]
    end
end

return a['2'];      -- This returns proper value 35
-- return a;            This returns empty array to node

节点文件- luaExec.js

let fs = require('fs');
let redis  = require('redis');
let client = redis.createClient();

client.on("error", cb);

function cb(err) {
    console.log("Error " + err);
}

client.eval(fs.readFileSync('groupBy.lua'), 0, (err, replies) => {
    if(err) cb(err);
    console.log(replies);
})

client.quit();

我用这个脚本保存了我的数据- saveStudentData.lua

redis.call("hmset","students:1", "name", "A", "class", 1, "marks", 5 );
redis.call("hmset","students:2", "name", "B", "class", 1, "marks", 10 );
redis.call("hmset","students:3", "name", "C", "class", 2, "marks", 15 );
redis.call("hmset","students:4", "name", "D", "class", 2, "marks", 20 );