如何將javascript數組保存爲redis列表

Question

以下代碼將整個數組保存爲redis列表中的單個值。但我想單獨保存數組值。我該怎麼做？

P.S對不起英文不好。

var redis = require('redis'), 
    client = redis.createClient(); 

var arr = [1,2,3]; 

client.rpush('testlist',arr); 

Answer 1

使用multi()流水線多個命令一次：

var redis = require('redis'), 
    client = redis.createClient(); 

var arr = [1,2,3]; 

var multi = client.multi() 

for (var i=0; i<arr.length; i++) { 
    multi.rpush('testlist', arr[i]); 
} 

multi.exec(function(errors, results) { 

}) 

最後調用exec()發送命令Redis的。

Answer 2

即使@gimenete答案的作品，做你想要什麼，最好的辦法是列表元素轉發作爲參數傳遞給RPUSH像這樣：

var redis = require('redis'), 
    client = redis.createClient(); 

var arr = [1,2,3]; 
client.rpush.apply(client, ['testlist'].concat(arr)); 

// ... or with a callback 
client.rpush.apply(client, ['testlist'].concat(arr).concat(function(err, ok){ 
    console.log(err, ok); 
})); 

優點： - 單指令會transmited到Redis的

缺點： - 一個極端情況：.apply將拋出一個RangeError: Maximum call stack size exceeded如果傳遞給RPUSH參數列表長度過大（有點OVE v8的100 000個項目）。

從MDC：

The consequences of applying a function with too many arguments (think more than tens of thousands of arguments) vary across engines (JavaScriptCore has hard-coded argument limit of 65536), because the limit (indeed even the nature of any excessively-large-stack behavior) is unspecified. Some engines will throw an exception. More perniciously, others will arbitrarily limit the number of arguments actually passed to the applied function.