假设我们有10个集合,那么我们必须在tag_id
的基础上找到计数。例如,如果tag_id
包含0和1,那么我们必须计算所有数据,以及计算没有tag_id
或tag_id
为空的数据。然后如果它有未读:false则输出到来,计算所有未读。
在false时查找tag_id的计数和未读的计数。
{
"_id": ObjectId("5912c7240520df77f0c2c18a"),
"email_id": "54",
"unread": "false",
"__v": NumberLong(0),
"tag_id": ["0"
]
}, {
"_id": ObjectId("5912c71e0520df77f0c2c189"),
"email_id": "55",
"unread": "false",
"__v": NumberLong(0),
"tag_id": [
"1"
]
}, {
"_id": ObjectId("5912c71d0520df77f0c2c186"),
"email_id": "51",
"unread": "false",
"__v": NumberLong(0),
"tag_id": [
"2", "1"
]
}
预期结果:
{
"data": [{
"tag_id": "1",
"count_email": 1,(count of email on the basis of tag_id)
"unread": 9(count the unread on the basis of output of tag_id)
}, {
"tag_id": "3",
"count_email": 45,
"unread": 3
}, {
"tag_id": "2",
"count_email": 5,
"unread": 4
}, {
"id": null,
"count_email": 52,
"unread": 35
}]
}
答案 0 :(得分:1)
您可以使用以下聚合管道。
以下查询将$unwind
tag_id
后跟$group
来计算email
和$cond
运算符以计算unread
电子邮件。
db.collection.aggregate(
{$unwind:{path:"$tag_id", preserveNullAndEmptyArrays:true}},
{$group:{
_id:"$tag_id",
count_email:{$sum:1},
unread:{$sum:{$cond:[{$eq:["$unread", "false"]}, 0, 1]}}
}
}
);