group by multiple mongodb code example
Example 1: group by mongo
db.sales.aggregate([
// First Stage
{
$match : { "date": { $gte: new ISODate("2014-01-01"), $lt: new ISODate("2015-01-01") } }
},
// Second Stage
{
$group : {
_id : { $dateToString: { format: "%Y-%m-%d", date: "$date" } },
totalSaleAmount: { $sum: { $multiply: [ "$price", "$quantity" ] } },
averageQuantity: { $avg: "$quantity" },
count: { $sum: 1 }
}
},
// Third Stage
{
$sort : { totalSaleAmount: -1 }
}
])
Example 2: mongodb group by several fields
db.books.aggregate([
{ "$group": {
"_id": {
"addr": "$addr",
"book": "$book"
},
"bookCount": { "$sum": 1 }
}},
{ "$group": {
"_id": "$_id.addr",
"books": {
"$push": {
"book": "$_id.book",
"count": "$bookCount"
},
},
"count": { "$sum": "$bookCount" }
}},
{ "$sort": { "count": -1 } },
{ "$limit": 2 },
{ "$project": {
"books": { "$slice": [ "$books", 2 ] },
"count": 1
}}
])