A document in collection called 'myCollection' looks like this:
{
_id : 57b4b4e028108d801738a472,
updatedAt : 2016-08-17T19:03:01.831+0000,
createdAt : 2016-08-17T19:02:56.887+0000,
from : 57b1c2fc4bf55ba009b36c84,
to : 57b1c75e4bf55ba009b36c85,
}
I need to count the occurrences of 'from' and 'to' and end up with collection of documents like this:
{
"_id" : 7b1c2fc4bf55ba009b36c84,
"occurredInFrom" : 12,
"occurredInTo" : 16
}
where _id comes from either '$from' or '$to'.
The incorrect aggregate query I've written is this:
{
$group: {
_id: "$from",
occurredInFrom: { $sum: 1 },
occurredInTo: { $sum: 1}
}
}
I can definitely see that _id: "$from" is not sufficient. Can you please show me the correct way?
Note: The structure of 'myCollection' is not final, if you think there is a better structure, please suggest it.
Try this
db.myCollection.aggregate([
{ $project:
{ _id: 0,
dir: [
{id:"$from", from:{"$sum":1}, to:{"$sum":0}},
{id:"$to", from:{"$sum":0}, to:{"$sum":1}}
]
}
},
{ $unwind : "$dir" },
{ $group:
{
_id: "$dir.id",
occurredInFrom: { $sum: "$dir.from" },
occurredInTo: { $sum: "$dir.to" }
}
}
])
Related
I have collection like this:
{
"_id" : ObjectId("4d663451d1e7242c4b68e000"),
"topic" : "abc",
"subLevel" : {
"id" : 1
}
}
{
"_id" : ObjectId("4d6634514cb5cb2c4b69e000"),
"topic" : "bce",
"subLevel" : {
"id" : 1
}
}
{
"_id" : ObjectId("4d6634514cb5cb2c4b70e000"),
"topic" : "bec",
"subLevel" : {
"id" : 2
}
}
{
"_id" : ObjectId("4d6634514cb5cb2c4b70e000"),
"topic" : "vvv",
"subLevel" : {
"id" : 3
}
}
and I need to count how many documents exist for provided subLevel.id list, for example if I provide 1 and 2 it should show me that for 1 we have 2 documents and for 2 only 1 document and simply omit document where subLevel.id is 3 as it's not in the list of id's.
I tried to do it with a aggregate
db.getCollection('products').aggregate( [
{ $project:
{ "has_sublevel" : {$in: [ "subLevel.id", [1 , 2 ]]} }
},
{ $group: { _id : "$subLevel.id", count: { $sum: 1 } } }
] )
but result is
{
_id : null,
count: 4
}
how can I do it, thanks in advance!
If transform it to SQL which I familiar more, query should look like this:
select subLevelId, count(id) FROM products where subLevelId in (1,2) group by subLevelId
If I've understand correctly, you are so so close, check this query:
First use $match to get only documents whose subLevel.id is 1 or 2.
Then, as you have done, $group by the id and sum to get total count:
db.collection.aggregate([
{
"$match": { "subLevel.id": { "$in": [ 1, 2 ] } }
},
{
"$group": { "_id": "$subLevel.id", "count": { "$sum": 1 } }
}
])
Example here
You will need this:
db.products.aggregate([ {$match:{ "subLevel.id":{ $in:[1,2] } }} , {$group:{ _id:"$subLevel.id" , count:{$sum:1} } } ])
which is same like:
db.products.aggregate([ {$match:{ $or:[{"subLevel.id":1},{"subLevel.id":2} ]}} , {$group:{ _id:"$subLevel.id" , count:{$sum:1} } } ])
You need to push the respective docs into their respective arrays and then get their sizes:
db.collection.aggregate([
{
"$match": {
"subLevel.id": {
$in: [
1,
2
]
}
}
},
{
$group: {
"_id": "$subLevel.id",
ids: {
$push: "$_id"
}
}
},
{
$project: {
_id: false,
ids: {
$size: "$ids"
}
}
}
])
Playgroud: https://mongoplayground.net/p/J1ei37l1K5-
I have a collection, lets call it 'user'. In this collection there is a property entries, which holds a variably sized array of strings,
I want to find out the total number of these strings across my collection.
db.users.find()
> [{ entries: [] }, { entries: ['entry1','entry2']}, {entries: ['entry1']}]
So far I have have made many attempts here are some of my closest.
db.users.aggregate([
{ $project:
{ numberOfEntries:
{ $size: "$entries" } }
},
{ $group:
{_id: { total_entries: { $sum: "$entries"}
}
}
}
])
What this gives me is a list of the users with the total number of entries, now what I want is each of the total_entries figures added up to get my total. Any ideas of what I am doing wrong. Or if there is a better way to start this?
A possible solution could be:
db.users.aggregate([{
$group: {
_id: 'some text here',
count: {$sum: {$size: '$entries'}}
}
}]);
This will give you the total count of all entries across all users and look like
[
{
_id: 'some text here',
count: 3
}
]
I would use $unwind in the case that you want individual entry counts.
That would look like
db.users.aggregate([
{ $unwind: '$entries' },
{$group: {
_id: '$entries',
count: {$sum: 1}
}
])
and this will give you something along the lines of:
[
{
_id: 'entry1',
count: 2
},
{
_id: 'entry2',
count: 1
}
]
In case you want the overall distinct nbr of entries:
> db.users.aggregate([
{ $unwind: "$entries" },
{ $group: { _id: "$entries" } },
{ $count: "total" }
])
{ "total" : 2 }
In case you want the overall nbr of entries:
> db.users.aggregate( [ { $unwind: "$entries" }, { $count: "total" } ] )
{ "total" : 3 }
This makes use of the "unwind" operator which flattens elements of an array from records:
> db.users.aggregate( [ { $unwind: "$entries" } ] )
{ "_id" : ObjectId("5a81a7a1318e1cfc10250430"), "entries" : "entry1" }
{ "_id" : ObjectId("5a81a7a1318e1cfc10250430"), "entries" : "entry2" }
{ "_id" : ObjectId("5a81a7a1318e1cfc10250431"), "entries" : "entry1" }
You were in the right direction though you just needed to specify an _id value of null in the $group stage to calculate accumulated values for all the input documents as a whole i.e.
db.users.aggregate([
{
"$project": {
"numberOfEntries": {
"$size": {
"$ifNull": ["$entries", []]
}
}
}
},
{
"$group": {
"_id": null, /* _id of null to get the accumulated values for all the docs */
"totalEntries": { "$sum": "$numberOfEntries" }
}
}
])
Or with just a single pipeline as:
db.users.aggregate([
{
"$group": {
"_id": null, /* _id of null to get the accumulated values for all the docs */
"totalEntries": {
"$sum": {
"$size": {
"$ifNull": ["$entries", []]
}
}
}
}
}
])
I want to return an aggregate of blog post tags and their total count. My blog posts are stored like so:
{
"_id" : ObjectId("532c323bb07ab5aace243c8e"),
"title" : "Fitframe.js - Responsive iframes made easy",
"tags" : [
"JavaScript",
"jQuery",
"RWD"
]
}
I'm then executing the following pipeline:
printjson(db.posts.aggregate(
{
$project: {
tags: 1,
count: { $add: 1 }
}
},
{
$unwind: '$tags'
},
{
$group: {
_id: '$tags',
count: {
$sum: '$count'
},
tags_lower: { $toLower: '$tags' }
}
},
{
$sort: {
_id: 1
}
}
));
So that the results are sorted correctly I need to sort on a lowercase version of each tag. However, when executing the above code I get the following error:
aggregate failed: {
"errmsg" : "exception: unknown group operator '$toLower'",
"code" : 15952,
"ok" : 0
}
Do I need to do another projection to add the lowercase tag?
Yes, you must add it to the projection. It will not work in the group, only specific operators like $sum ( http://docs.mongodb.org/manual/reference/operator/aggregation-group/ ) are counted as $group operators and capable of being used on that level of the group
You don't need to add another projection ... you could fix it when you do the $group:
db.posts.aggregate(
{
$project: {
tags: 1,
count: { $add: 1 }
}
},
{
$unwind: '$tags'
},
{
$group: {
_id: { tag: '$tags', lower: { $toLower : '$tags' } },
count: {
$sum: '$count'
}
}
},
{
$sort: {
"_id.lower": 1
}
}
)
In the above example, I've preserved the original name and added the lower case version to the _id.
Add another projection step between $unwind and $grop:
...
{$project: {
tags: {$toLower: '$tags'},
count: 1
}}
...
And remove tags_lower from $group
I am very new to mongodb concepts
outerob{
_id:111,
name:xxx,
dependents : [ {
name:a,
age:11
}
{
name:b,
age:12
}
{
name:a,
age:11
}
]
}
I have collection like this. I want to count number of dependents. please help me with this
thanks in advance
You can find the number of items in array by using Aggregation framework as follows :
db.myCollection.aggregate(
{ $unwind: "$dependents" },
{ $group: { _id: "$_id", count: { $sum: 1 }}}
);
You can find the number of items with specific name as follows :
db.myCollection.aggregate(
{ $unwind: "$dependents" },
{ $match : {"dependents.name" : "a"}},
{ $group: { _id: "$_id", count: { $sum: 1 }}}
);
try
x=db.collection.find({_id:111}).toArray()[0].dependents.length
I'm trying to sum some values in an array of documents, with no luck.
This is the Document
db.Cuentas.find().pretty()
{
"Agno": "2013",
"Egresos": [
{
"Fecha": "28-01-2013",
"Monto": 150000,
"Detalle": "Pago Nokia Lumia a #josellop"
},
{
"Fecha": "29-01-2013",
"Monto": 4000,
"Detalle": "Cine, Pelicula fome"
}
],
"Ingresos": [],
"Mes": "Enero",
"Monto": 450000,
"Usuario": "MarioCares"
"_id": ObjectId(....)
}
So, i need the sum of all the "Monto" in "Egresos" for the "Usuario": "MarioCares". In this example 154000
Using aggregation i use this:
db.Cuentas.aggregate(
[
{ $match: {"Usuario": "MarioCares"} },
{ $group:
{
_id: null,
"suma": { $sum: "$Egresos.Monto" }
}
}
]
)
But i always get
{ "result" : [{ "_id" : null, "suma" : 0 }], "ok" : 1 }
What am i doing wrong ?
P.D. already see this and this
As Sammaye indicated, you need to $unwind the Egresos array to duplicate the matched doc per array element so you can $sum over each element:
db.Cuentas.aggregate([
{$match: {"Usuario": "MarioCares"} },
{$unwind: '$Egresos'},
{$group: {
_id: null,
"suma": {$sum: "$Egresos.Monto" }
}}
])
You can do also by this way. don't need to group just project your fields.
db.Cuentas.aggregate([
{ $match: { "Usuario": "MarioCares" } },
{
$project: {
'MontoSum': { $sum: "$Egresos.Monto" }
}
}
])
Since mongoDB version 3.4 you can use $reduce to sum array items:
db.collection.aggregate([
{
$match: {Usuario: "MarioCares"}
},
{
$project: {
suma: {
$reduce: {
input: "$Egresos",
initialValue: 0,
in: {$add: ["$$value", "$$this.Monto"]}
}
}
}
}
])
Playground example