在 MongoDB 中使用乘法聚合 [英] Using multiply aggregation with MongoDB
本文介绍了在 MongoDB 中使用乘法聚合的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我有几个文件看起来像这样:
I have several documents that looks like this:
{
"hostname" : "server1.example.com",
"virtual" : true,
"processors" : {
"cores" : 1,
"sockets" : 4
}
}
{
"hostname" : "server2.example.com",
"virtual" : false,
"processors" : {
"cores" : 2,
"sockets" : 2
}
}
我正在尝试输出每个文档的主机名、虚拟内核数和内核总数.我不断收到让我难倒的语法错误.这是我的查询和语法错误.
I am trying to output the hostname, virtual and total number of cores for each document. I keep getting a syntax error that has me stumped. Here is my query and the syntax error.
c.aggregate( {
$project: {
hostname: 1,
total-cores: {$multiply: ["$processors.sockets", "$processors.cores"]},
virtual: 1,
_id: 0
}
});
Thu Apr 25 14:12:18 SyntaxError: missing : after property id (shell):1
从文档来看,这应该可行.我错过了什么?我正在运行 MongoDB 2.2.2.
Judging from the documentation, this should work. What am I missing? I am running MongoDB 2.2.2.
http://docs.mongodb.org/manual/reference/aggregation/project/
推荐答案
引用 total-cores
键,以便使用嵌入的连字符正确解析它:
Quote the total-cores
key so that it's parsed correctly with the embedded hyphen:
c.aggregate({
$project: {
hostname: 1,
"total-cores": {$multiply: ["$processors.sockets","$processors.cores"]},
virtual: 1,
_id: 0
}
});
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