获取不同的ISO日期,按日,月,年 [英] Get distinct ISO dates by days, months, year
问题描述
我想为我的MongoDB中的所有文档对象获得一组独特的年份和数月。
I want to get a distinct set of years and months for all document objects in my MongoDB.
例如,如果文件有日期:
For example, if documents have dates:
- 2015/08/11
- 2015/08/11
- 2015/08/12
- 2015/09/14
- 2014/10/30
- 2014/10/30
- 2014/08/11
- 2015/08/11
- 2015/08/11
- 2015/08/12
- 2015/09/14
- 2014/10/30
- 2014/10/30
- 2014/08/11
返回所有文档的唯一的月份和年份,例如:
Return unique months and years for all documents, ex:
- 2015/08
- 2015/09
- 2014/10
- 2014/08
- 2015/08
- 2015/09
- 2014/10
- 2014/08
模式片段:
var myObjSchema = mongoose.Schema({
date: Date,
request: {
...
我尝试使用 distinct
反对模式字段 date
:
I tried using distinct
against schema field date
:
db.mycollection.distinct('date',{},{})
但是这个给了重复的日期输出片段:
But this gave duplicate dates. Output snippet:
ISODate("2015-08-11T20:03:42.122Z"),
ISODate("2015-08-11T20:53:31.135Z"),
ISODate("2015-08-11T21:31:32.972Z"),
ISODate("2015-08-11T22:16:27.497Z"),
ISODate("2015-08-11T22:41:58.587Z"),
ISODate("2015-08-11T23:28:17.526Z"),
ISODate("2015-08-11T23:38:45.778Z"),
ISODate("2015-08-12T06:21:53.898Z"),
ISODate("2015-08-12T13:25:33.627Z"),
ISODate("2015-08-12T14:46:59.763Z")
所以问题是:
- a:如何完成上述?
- b:是否可以指定要区分哪一部分日期?像
distinct('date.month'...)
?
- a: How can I accomplish the above?
- b: Is it possible to specify which part of the date you want distinct? Like
distinct('date.month'...)
?
编辑:我发现你可以通过以下查询获得这些日期,但是结果并不明确:
I've found u can get these dates and such with the following query, however the results are not distinct:
db.mycollection.aggregate(
[
{
$project : {
month : {
$month: "$date"
},
year : {
$year: "$date"
},
day: {
$dayOfMonth: "$date"
}
}
}
]
);
输出:重复
{ "_id" : "", "month" : 7, "year" : 2015, "day" : 14 }
{ "_id" : "", "month" : 7, "year" : 2015, "day" : 15 }
{ "_id" : "", "month" : 7, "year" : 2015, "day" : 15 }
推荐答案
您需要在投影后对文档进行分组,并使用 $ addToSet
累加器运算符
You need to group your document after the projection and use $addToSet
accumulator operator
db.mycollection.aggregate([
{ "$project": {
"year": { "$year": "$date" },
"month": { "$month": "$date" }
}},
{ "$group": {
"_id": null,
"distinctDate": { "$addToSet": { "year": "$year", "month": "$month" }}
}}
])
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