问题
db.logdata.findOne()
{
"_id" : ObjectId("552cfc949258ff1fa8686f1a"),
"ldl_date" : "2015-04-09",
"ldl_mmo_id" : 5,
"ldl_master_info_id" : 11,
"ldl_publication_info_id" : 41616,
"detail" : [
{
"ldl_id" : 54261629,
"ldl_xml_info_id" : 37437691,
"ldl_distribution_id" : 3289,
"ldl_local_flag" : 1,
"ldl_ftp_flag" : 0,
"ldl_time" : "2015-04-09 06:36:46"
}
]
}
I need to access the ldl_local_flag and count of the ldl_local_flag I tried following query but not get the exact result.
The query is
db.logdata.aggregate([
{
$group: {
_id: "$ldl_mmo_id",
total: {
$sum: "$detail.ldl_local_flag"
}
}
},
{
$limit: 10
}
])
And output is
{ "_id" : 1, "total" : 0 }
{ "_id" : 2, "total" : 0 }
{ "_id" : 3, "total" : 0 }
{ "_id" : 4, "total" : 0 }
{ "_id" : 5, "total" : 0 }
please help me..........
回答1:
This might be helpful to you:
db.collection.aggregate({
$unwind: '$detail'
},
{
$group: {
"_id": "$detail.ldl_local_flag",
"sum": {
"$sum": "$detail.ldl_local_flag"
}
}
},
{
$project: {
"local_flags": "$_id",
"count": "$sum"
}
})
来源：https://stackoverflow.com/questions/29647609/how-to-access-embeded-documents-using-aggregation-function