I have an aggregate to pull metrics from a collection of "share" actions. These metrics are grouped by day and the platform(twitter, pintrest, etc). Each stage works fine except when it comes to formatting the output in a $project stage, I cannot seem to get the platform string to project in my output. I see it in the _id still, however I cannot get it to project to the other field.
我有一个聚合来从一组“共享”操作中提取指标。这些指标按日和平台(twitter,pintrest等)分组。每个阶段工作正常,除非在$ project阶段格式化输出,我似乎无法在我的输出中获得平台字符串。我仍然在_id中看到它,但是我不能让它投射到另一个领域。
The aggregation is as follows:
汇总如下:
{
$unwind: "$platforms"
},
{
$project: {
day: {$dayOfMonth: "$created_at"},
month: {$month: "$created_at"},
year: {$year: "$created_at"},
platforms: 1
}
},
{
$group: {
_id: {
platorms: "$platforms",
day: "$day",
month: "$month",
year: "$year"
},
count: {$sum: 1}
}
},
{
$project: {
day: "$_id.day",
month: "$_id.month",
year: "$_id.year",
platform: "$_id.platforms",
count: 1
}
}
The output of the following is:
以下输出是:
{
"result" : [
{
"_id" : {
"platorms" : "EMAIL",
"day" : 28,
"month" : 4,
"year" : 2015
},
"count" : 1,
"day" : 28,
"month" : 4,
"year" : 2015
},
{
"_id" : {
"platorms" : "EMAIL",
"day" : 27,
"month" : 4,
"year" : 2015
},
"count" : 10,
"day" : 27,
"month" : 4,
"year" : 2015
},
{
"_id" : {
"platorms" : "SMS",
"day" : 27,
"month" : 4,
"year" : 2015
},
"count" : 1,
"day" : 27,
"month" : 4,
"year" : 2015
},
{
"_id" : {
"platorms" : "FACEBOOK",
"day" : 27,
"month" : 4,
"year" : 2015
},
"count" : 1,
"day" : 27,
"month" : 4,
"year" : 2015
}, ...
The integers for day, month, and year project fine, however platforms does not.
日,月和年的整数项目很好,但平台没有。
1 个解决方案
#1
This is because in your $group stage you have compound _id with platorms: "$platforms" (missing f in field name) and you are projecting the $_id.platforms in your last $project stage and since such field doesn't exist you will not get any result. You can also exclude the _id field using _id: 0.
这是因为在$ group阶段你有复合_id与platorms:“$ platforms”(在字段名称中缺少f)并且你在上一个$ project阶段投射$ _id.platforms,因为这样的字段不存在你不会得到任何结果。您还可以使用_id:0排除_id字段。
Change your $group stage to:
将$ group阶段更改为:
{
$group: {
_id: {
platforms: "$platforms",
day: "$day",
month: "$month",
year: "$year"
},
count: {$sum: 1}
}
}
#1
This is because in your $group stage you have compound _id with platorms: "$platforms" (missing f in field name) and you are projecting the $_id.platforms in your last $project stage and since such field doesn't exist you will not get any result. You can also exclude the _id field using _id: 0.
这是因为在$ group阶段你有复合_id与platorms:“$ platforms”(在字段名称中缺少f)并且你在上一个$ project阶段投射$ _id.platforms,因为这样的字段不存在你不会得到任何结果。您还可以使用_id:0排除_id字段。
Change your $group stage to:
将$ group阶段更改为:
{
$group: {
_id: {
platforms: "$platforms",
day: "$day",
month: "$month",
year: "$year"
},
count: {$sum: 1}
}
}