Get Last Date within Range for Each Id Group - mongodb

Question

Let say I have a collection with the following item:
[{myId:0,date:01.01.17,data:1000},
{myId:1,date:01.02.17,data:2000},
{myId:0,date:01.03.17,data:3000},
{myId:1,date:01.04.17,data:4000},
{myId:0,date:01.05.17,data:5000}]
I want to create a query that get a date as a parameter and return an array with single object for evrey myId that have the maximum date bellow the requested one.
For example calling the query with 15.03.17 date return:
[{myId:1,date:01.02.17,data:2000},
{myId:0,date:01.03.17,data:3000}]
And calling query with 15.01.17 date return
[{myId:0,date:01.01.17,data:1000}]
I'm looking for an answer that doesn't use db.eval

Answer 1

Fixing your data to make it valid:
db.junk.insertMany([
{myId:0,date: new Date("2017-01-01"),data:1000},
{myId:1,date: new Date("2017-02-01"),data:2000},
{myId:0,date: new Date("2017-03-01"),data:3000},
{myId:1,date: new Date("2017-04-01"),data:4000},
{myId:0,date: new Date("2017-05-01"),data:5000}
])
You run an aggregate statement, filtering the entries via $match, then applying $sort to ensure the order and using $last for the "max" on each grouping boundary:
db.junk.aggregate([
{ "$match": { "date": { "$lte": new Date("2017-03-15") } } },
{ "$sort": { "date": 1 } },
{ "$group": {
"_id": "$myId",
"date": { "$last": "$date" },
"data": { "$last": "$data" }
}}
])
Returns:
/* 1 */
{
"_id" : 1.0,
"date" : ISODate("2017-02-01T00:00:00.000Z"),
"data" : 2000.0
}
/* 2 */
{
"_id" : 0.0,
"date" : ISODate("2017-03-01T00:00:00.000Z"),
"data" : 3000.0
}
And for the other date:
db.junk.aggregate([
{ "$match": { "date": { "$lte": new Date("2017-01-15") } } },
{ "$sort": { "date": 1 } },
{ "$group": {
"_id": "$myId",
"date": { "$last": "$date" },
"data": { "$last": "$data" }
}}
])
Returns:
/* 1 */
{
"_id" : 0.0,
"date" : ISODate("2017-01-01T00:00:00.000Z"),
"data" : 1000.0
}
If you really must you can add a $sort as the final pipeline stage in order to ensure the order of _id ( myId value ) returned:
db.junk.aggregate([
{ "$match": { "date": { "$lte": new Date("2017-03-15") } } },
{ "$sort": { "date": 1 } },
{ "$group": {
"_id": "$myId",
"date": { "$last": "$date" },
"data": { "$last": "$data" }
}},
{ "$sort": { "_id": 1 } }
])