mongodb get count group by - mongodb

Question

I have problem with get count by group.
"BOOL_LIST": [
{
"BOOK_TITLE": "the lord of the ring",
"INDEX": 1,
"READ": {
"NORMAL": {
"SN": "12222ea8e679518021f01a19cc4d95b9483c3",
"RESULT": "booked"
},
"bNORMAL": {
"SN": "4444454b51ea8e679518021f01a19cc4d95b9483c3",
"RESULT": "yet"
}
}
},....
I want to get output like below.
[{BOOL_TITLE:"the lord of the ring", NORMAL.booked_count : 2, bNORMAL.booked_count :1},
{BOOL_TITLE:"Mr.porter", NORMAL.booked_count : 21, bNORMAL.booked_count :1}, ...]
I have a problem with using $group. How can I do this?

Answer 1

You can use this script.
db.verification_job.aggregate( [
{ $unwind: "$BOOL_LIST" },
{ $group : {_id : {BOOK_TITLE: "$BOOL_LIST.BOOK_TITLE"}
, NORMAL_booked_count : { $sum : { $cond:[ { $eq: ["$BOOL_LIST.READ.NORMAL.RESULT", "booked" ] } , 1, 0 ] } }
, bNORMAL_booked_count : { $sum : { $cond:[ { $eq: ["$BOOL_LIST.READ.bNORMAL.RESULT", "booked" ] } , 1 , 0 ] } }
}}
] )
For more accurate testing, I assumed we have this sample data.
db.verification_job.insert({
"BOOL_LIST": [
{
"BOOK_TITLE": "the lord of the ring",
"INDEX": 1,
"READ": {
"NORMAL": {
"SN": "12222ea8e679518021f01a19cc4d95b9483c3",
"RESULT": "booked"
},
"bNORMAL": {
"SN": "4444454b51ea8e679518021f01a19cc4d95b9483c3",
"RESULT": "yet"
}
}
},
{
"BOOK_TITLE": "the lord of the ring",
"INDEX": 2,
"READ": {
"NORMAL": {
"SN": "12222ea8e679518021f01a19cc4d95b9483c3",
"RESULT": "yet"
},
"bNORMAL": {
"SN": "4444454b51ea8e679518021f01a19cc4d95b9483c3",
"RESULT": "booked"
}
}
},
{
"BOOK_TITLE": "Mr.porter",
"INDEX": 3,
"READ": {
"NORMAL": {
"SN": "12222ea8e679518021f01a19cc4d95b9483c3",
"RESULT": "booked"
},
"bNORMAL": {
"SN": "4444454b51ea8e679518021f01a19cc4d95b9483c3",
"RESULT": "yet"
}
}
}
]
})
And I get this output as result.
{ "_id" : { "BOOK_TITLE" : "Mr.porter" }, "NORMAL_booked_count" : 1, "bNORMAL_booked_count" : 0 }
{ "_id" : { "BOOK_TITLE" : "the lord of the ring" }, "NORMAL_booked_count" : 1, "bNORMAL_booked_count" : 1 }

Answer 2

Modified collection Schema, READ is modified into array of sub documents rather than nested sub documents, but if you cannot do this modification in the schema please use $objectToArray to modify the document into array and then you can proceed with $unwind. Please note that $objectToArray is available only from mongodb version 3.4.4
db.collection.aggregate([
{$unwind:"$BOOL_LIST"},
{$unwind:"$BOOL_LIST.READ"},
{$group:{_id:{"book_title":"$BOOL_LIST.BOOK_TITLE",
"result_bnormal":"$BOOL_LIST.READ.bNORMAL.RESULT",
"result_normal":"$BOOL_LIST.READ.NORMAL.RESULT" },
count:{$sum:1}}
}])
sample document after the modification
{"BOOL_LIST": [
{
"BOOK_TITLE": "the lord of the ring",
"INDEX": 1,
"READ": [{
"NORMAL": {
"SN": "12222ea8e679518021f01a19cc4d95b9483c3",
"RESULT": "booked"
}},
{"bNORMAL": {
"SN": "4444454b51ea8e679518021f01a19cc4d95b9483c3",
"RESULT": "yet"
}}
]
},
{
"BOOK_TITLE": "The coblet of fire",
"INDEX": 2,
"READ": [
{"NORMAL": {
"SN": "23232ea8e679518021f01a19cc4d95b9483e3",
"RESULT": "booked"
}},
{"bNORMAL": {
"SN": "5555554b51ea8e679518021f01a19cc4d95b9483c3",
"RESULT": "yet"
}}
]
}
]}
After executing our query in the modified collection the result is
{
"_id" : {
"book_title" : "the lord of the ring",
"result_normal" : "booked"
},
"count" : 1
}
{
"_id" : {
"book_title" : "the lord of the ring",
"result_bnormal" : "yet"
},
"count" : 1
}
{
"_id" : {
"book_title" : "The coblet of fire",
"result_bnormal" : "yet"
},
"count" : 1
}
{
"_id" : {
"book_title" : "The coblet of fire",
"result_normal" : "booked"
},
"count" : 1
}