Count same types element in array mongodb - mongodb

Question

{
_id:1, members: [
{
name:"John",
status:"A"
},
{
name:"Alex",
status:"D"
},
{
name:"Jack",
status:"A"
},
{
name:"Robin",
status:"D"
}
]}
That is Channel document.
Now I need to count all elements in members array where status equal to 'A'.
For example the above doc has 2 members with status 'A'.
How can I achieve this?

Answer 1

You can use mongodb-count to achieve the desired result.
Returns the count of documents that would match a find() query. The db.collection.count() method does not perform the find() operation but instead counts and returns the number of results that match a query.
So your query will be
var recordcount = db.collName.count({"members.status":"A"});
Now recordCount will be number of records that matches {"members.status":"A"} query.

Answer 2

Here Is your Json file
{
"_id" : ObjectId("575915653b3cc43fca1fca4c"),
"members" : [
{
"name" : "John",
"status" : "A"
},
{
"name" : "Alex",
"status" : "D"
},
{
"name" : "Jack",
"status" : "A"
},
{
"name" : "Robin",
"status" : "D"
}
]
}
And you want to the count of all elements in members array where
status equal to 'A'.
you have to try this one to find out your count
db.CollectionName.aggregate([{
"$project": {
"members": {
"$filter": {
"input": "$members",
"as": "mem",
"cond": {
"$eq": ["$$mem.status", "A"]
}
}
}
}
}, {
"$project": {
"membersize": {
"$size": "$members"
}
}
}]).pretty()
And you found your answer is like that { "_id" :
ObjectId("575915653b3cc43fca1fca4c"), "membersize" : 2 }
try this one for old version......
db.CollectionName.aggregate([{"$unwind":"$members"},{"$match":{"members.status":"A"}},{"$group":{_id:"$_id","memberscount":{"$sum":1}}}]).pretty()
{ "_id" : ObjectId("575915653b3cc43fca1fca4c"), "memberscount" : 2 }

Answer 3

Here Is your Json file
{
"_id" : ObjectId("575915653b3cc43fca1fca4c"),
"members" : [
{
"name" : "John",
"status" : "A"
},
{
"name" : "Alex",
"status" : "D"
},
{
"name" : "Jack",
"status" : "A"
},
{
"name" : "Robin",
"status" : "D"
}
]
}
And you want to the count of all elements in members array where
status equal to 'A'.
you have to try this one to find out your count
db.CollectionName.aggregate([{
"$project": {
"members": {
"$filter": {
"input": "$members",
"as": "mem",
"cond": {
"$eq": ["$$mem.status", "A"]
}
}
}
}
}, {
"$project": {
"membersize": {
"$size": "$members"
}
}
}]).pretty()
And you found your answer is like that { "_id" :
ObjectId("575915653b3cc43fca1fca4c"), "membersize" : 2 }