javascript 如何将javascript数组保存为redis列表
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How to save javascript array as redis list
提问by user2522545
The following code save the whole array as single value in redis list. But I want to save array values individually. How can I do it?
以下代码将整个数组保存为 redis 列表中的单个值。但我想单独保存数组值。我该怎么做？
P.S So sorry for poor English.
PS 很抱歉英语不好。
var redis = require('redis'),
client = redis.createClient();
var arr = [1,2,3];
client.rpush('testlist',arr);
回答by gimenete
Use multi()to pipeline multiple commands at once:
用于multi()一次管道化多个命令：
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) {
})
And finally call exec()to send the commands to redis.
最后调用exec()将命令发送到redis。
回答by FGRibreau
Even if @gimenete answer works, the best way to do what you want is to forward the list elements as arguments to rpush like so:
即使@gimenete 回答有效，做你想做的最好的方法是将列表元素作为参数转发给 rpush，如下所示：
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);
}));
Pros: - a single instruction will be transmited to Redis
优点： - 一条指令将被传输到 Redis
Cons:
- a corner-case: .applywill throw a RangeError: Maximum call stack size exceededif the arguments list length passed to rpush is too large (a little over 100 000 items for v8).
缺点： - 一个极端情况：如果传递给 rpush 的参数列表长度太大（v8 的项目超过 100 000 项），.apply则会抛出 a RangeError: Maximum call stack size exceeded。
From MDC:
来自 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.
应用具有过多参数的函数（想想超过数万个参数）的后果因引擎而异（JavaScriptCore 的硬编码参数限制为 65536），因为限制（实际上甚至任何过大堆栈的性质）行为）未指定。有些引擎会抛出异常。更有害的是，其他人会任意限制实际传递给应用函数的参数数量。
