mongodb 如何使用多个 $cond 对查询进行分组？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/20836978/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
How to group query with multiple $cond?
提问by yountae.kang
I want to query like below, but this contains only one $cond.
我想像下面这样查询，但这只包含一个$cond.
How to query with two $cond?
如何查询两个$cond？
collection.aggregate(
{
$match : {
'_id' : {$in:ids}
}
},
{
$group: {
_id: '$someField',
...
count: {$sum: { $cond: [ { $eq: [ "$otherField", false] } , 1, 0 ] }}
}
},
function(err, result){
...
}
);
回答by Asya Kamsky
You want to use a compound expression inside {$cond:[]}- something like:
您想在内部使用复合表达式{$cond:[]}- 例如：
collection.aggregate(
{
$match : {
'_id' : {$in:ids}
}
},
{
$group: {
_id: '$someField',
...
count: {$sum: { $cond: [ {$and : [ { $eq: [ "$otherField", false] },
{ $eq: [ "$anotherField","value"] }
] },
1,
0 ] }}
}
},
function(err, result){
...
}
);
The $andoperatoris documented here: http://docs.mongodb.org/manual/reference/operator/aggregation/#boolean-operators
该$and操作记录在这里：http://docs.mongodb.org/manual/reference/operator/aggregation/#boolean-operators
