{
"_id" : ObjectId("53692eb238ed04c824679f18"),
"firstUserId" : 1,
"secondUserId" : 17,
"messages" : [
{
"_id" : ObjectId("5369338997b964b81d579fc6"),
"read" : true,
"dateTime" : 1399403401,
"message" : "d",
"userId" : 1
},
{
"_id" : ObjectId("536933c797b964b81d579fc7"),
"read" : false,
"dateTime" : 1399403463,
"message" : "asdf",
"userId" : 17
}
]
}
I'm trying to select all documents that have firstUserId = 1 and also have sub documents
that have userId differnet ($ne) to 1 and read = false.
I tried:
db.usermessages.find({firstUserId: 1, "messages.userId": {$ne: 1}, "messages.read": false})
But it returns empty cause messages have both 1 and 17.
And also how to count subdocuments that have given case?
Are you trying to get the count of all the documents which are returned after your match criteria? If Yes, then you might consider using aggregation framework. http://docs.mongodb.org/manual/aggregation/
Something like below could be done to get you the counts:
db.usermessages.aggregate(
{ "$unwind": "$messages" },
{ "$match":
{ "firstUserId": 1,
"messages.userId": { "$ne" : 1},
"messages.read": false
}
},
{ "$group": { "_id" :null, "count" : { "$sum": 1 } } }
)
Hope this helps.
PS: I have not tried this on my system.
Related
I need to create a query in mongodb that needs to return the SECOND TO THE LAST document. I am planning to use $group for this query but i dont know what aggregation function to use. I only know $first and $last.
I have an example collection below and also include the expected output. Thank you!
"_id" : ObjectId("60dc27ac54b7c46bfa1b84b4"),
"auditlogs" : [
{
"_id" : ObjectId("60dc27ac54b7c46bfa1b84be"),
"userid" : ObjectId("5ffe702d59a9205db81fcb69"),
"action" : "ADDTRANSACTION"
},
{
"_id" : ObjectId("60dc27ac54b7c46bfa1b84bd"),
"userid" : ObjectId("5ffe644f9493e05db9245192"),
"action" : "EDITPROFILE"
},
{
"_id" : ObjectId("60dc27ac54b7c46bfa1b84bc"),
"userid" : ObjectId("5ffe64949493e05db9245197"),
"action" : "DELETETRANSACTION"
} ]
"_id" : ObjectId("60dc27ac54b7c46bfa1b75ge2"),
"auditlogs" : [
{
"_id" : ObjectId("60dc27ac54b7c46bfa1b84bb"),
"userid" : ObjectId("5ffe64b69493e05db924519b"),
"action" : "ADDTRANSACTION"
},
{
"_id" : ObjectId("60dc27ac54b7c46bfa1b84ba"),
"userid" : ObjectId("5ffe65419493e05db92451d4"),
"action" : "ADDTRANSACTION"
},
{
"_id" : ObjectId("60dc27ac54b7c46bfa1b84b9"),
"userid" : ObjectId("5ffe65689493e05db92451d9"),
"action" : "CHANGEACCESS"
},
{
"_id" : ObjectId("60dc27ac54b7c46bfa1b84b8"),
"userid" : ObjectId("5ffe65819493e05db92451dd"),
"action" : "DELETETRANSACTION"
},
{
"_id" : ObjectId("60dc27ac54b7c46bfa1b84b7"),
"userid" : ObjectId("5ffe65df9493e05db92451f3"),
"action" : "EDITPROFILE",
]
OUTPUT:
{"_id" : ObjectId("60dc27ac54b7c46bfa1b84b4"),"_id" : ObjectId("60dc27ac54b7c46bfa1b84bd"),"userid" : ObjectId("5ffe644f9493e05db9245192"),"action" : "EDITPROFILE"},
{"_id" : ObjectId("60dc27ac54b7c46bfa1b75ge2"),"_id" : ObjectId("60dc27ac54b7c46bfa1b84b8"),"userid" : ObjectId("5ffe65819493e05db92451dd"),"action" : "DELETETRANSACTION"}
You can't have two _id keys in one single object.
I've made the parent object's id to _parentId you can give it's a name anything you want except _id
Aggregation:
db.collection.aggregate([
{
$unwind: "$auditlogs"
},
{
"$project": {
"_parentId": "$_id",
"_id": "$auditlogs._id",
"action": "$auditlogs.action",
"userid": "$auditlogs.userid",
}
}
])
Playground
You can slice the array by -2 to get the last two item, then by 1 to get first one. Therefore, the array will be left the second to the last. Finally, unwind auditlogs so it can be changed from array to object which is structure that you want.
db.collection.aggregate([
{
$project: { auditlogs : { $slice: [ "$auditlogs", -2 ] } }
},
{
$project: { auditlogs : { $slice: [ "$auditlogs", 1 ] } }
},
{
$unwind: "$auditlogs"
}
])
I'm trying to write a Mongo DB query where I do the following,
JSON list - Representing documents in my collection,
Industry[]:
{
"_id" : ObjectId("57aa6058be0c853c8cee34cd"),
"options": {
"paramList" : [
{
"name" : "industryCategory",
"value" : "Travel",
"mandatory" : true
},
{
"name" : "someOtherThing",
"value" : "dontMind",
"mandatory" : true
}
]
}
"mostRecent" : true
},
{
"_id" : ObjectId("57aa6058be0c853c8cee34cd"),
"options": {
"paramList" : [
{
"name" : "industryCategory",
"value" : "Dining",
"mandatory" : true
},
{
"name" : "someOtherThing",
"value" : "dontMind",
"mandatory" : true
}
]
}
"mostRecent" : true
},
{
"_id" : ObjectId("57aa6058be0c853c8cee34cd"),
"options": {
"paramList" : [
{
"name" : "industryCategory",
"value" : "Travel",
"mandatory" : true
},
{
"name" : "someOtherThing",
"value" : "dontMind",
"mandatory" : true
}
]
}
"mostRecent" : true
}
I'm trying to group and get a count of values for those paramList - values where name is industryCategory. Essentially, the output I am looking for is something like this,
Travel: 2
Dining: 1
I'm trying to do the following,
Industry is the name of the collection,
db.Industry.aggregate (
[
{$match: {mostRecent: true}},
{$group: {
_id: '$options.paramList.value',
count: {$sum: 1}
}},
{$match: {'options.paramList.name': 'industryCategory'}}
])
I'm getting an empty result. Please suggest what I can do
Well, I didn't have anyone answering. But, in the meanwhile I managed to figure it out myself. Posting the answer below,
aggregate (
[
{"$match": {mostRecent: true}},
{"$unwind" : "$options.paramList"},
{"$group" :
{
_id: "$options.paramList.value",
count: {$sum : 1}
}
}
]
Essentially, use unwind wherever you have to iterate over arrays (a list of sub-documents). This has been a productive learning, at least for me.
This is my query:
db.getCollection('grades').
aggregate([{ "$match" : { "class_id" : 28, "student_id" : 0 } },
{ "$unwind" : "$scores" },
{ "$match" : { "scores.type" : "homework" } },
{ "$skip" : 3 }, { "$limit" : 3 },
{ "$group" : { "_id" : { "id" : "$_id" }, "scores" : { "$push" : "$scores" } } },
{ "$project" : { "_id" : "$_id.id", "scores" : 1 } }])
scores - is a nested array of objects. Score object - {type: "someType", score: someScore}. This query returns one document.
The problem: array of scores has 6 objects and 4 of them have type homework.
The result, what I've received: http://prntscr.com/bq217r
The original document: http://prntscr.com/bq23bv
Why skip-limit performed before match operator? How can I fix it?
As per attached screenshot everything looks OK.
we have 4 elements 1 2 3 4, then we are skipping 3, so we get 4 at the end... and 53 is the value :-)
btw your skip/limit is after $match
Our project database has a capped collection called values which gets updated every few minutes with new data from sensors. These sensors all belong to a single sensor node, and I would like to query the last data from these nodes in a single aggregation. The problem I am having is filtering out just the last of ALL the types of sensors while still having only one (efficient) query. I looked around and found the $group argument, but I can't seem to figure out how to use it correctly in this case.
The database is structured as follows:
nodes:
{
"_id": 681
"sensors": [
{
"type": "foo"
},
{
"type": "bar"
}
]
}
values:
{
"_id" : ObjectId("570cc8b6ac55850d5740784e"),
"timestamp" : ISODate("2016-04-12T12:06:46.344Z"),
"type" : "foo",
"nodeid" : 681,
"value" : 10
}
{
"_id" : ObjectId("190ac8b6ac55850d5740776e"),
"timestamp" : ISODate("2016-04-12T12:06:46.344Z"),
"type" : "bar",
"nodeid" : 681,
"value" : 20
}
{
"_id" : ObjectId("167bc997bb66750d5740665e"),
"timestamp" : ISODate("2016-04-12T12:06:46.344Z"),
"type" : "bar",
"nodeid" : 200,
"value" : 20
}
{
"_id" : ObjectId("110cc9c6ac55850d5740784e"),
"timestamp" : ISODate("2016-04-09T12:06:46.344Z"),
"type" : "foo",
"nodeid" : 681,
"value" : 12
}
so let's imagine I want the data from node 681, I would want a structure like this:
nodes:
{
"_id": 681
"sensors": [
{
"_id" : ObjectId("570cc8b6ac55850d5740784e"),
"timestamp" : ISODate("2016-04-12T12:06:46.344Z"),
"type" : "foo",
"nodeid" : 681,
"value" : 10
},
{
"_id" : ObjectId("190ac8b6ac55850d5740776e"),
"timestamp" : ISODate("2016-04-12T12:06:46.344Z"),
"type" : "bar",
"nodeid" : 681,
"value" : 20
}
]
}
Notice how one value of foo is not queried, because I want to only get the latest value possible if there are more than one value (which is always going to be the case). The ordering of the collection is already according to the timestamp because the collection is capped.
I have this query, but it just gets all the values from the database (which is waaay too much to do in a lifetime, let alone one request of the web app), so I was wondering how I would filter it before it gets aggregated.
query:
db.nodes.aggregate(
[
{
$unwind: "$sensors"
},
{
$match:{
nodeid: 681
}
},
{
$lookup:{
from: "values", localField: "sensors.type", foreignField: "type", as: "sensors"
}
}
}
]
)
Try this
// Pipeline
[
// Stage 1 - sort the data collection if not already done (optional)
{
$sort: {
"timestamp":1
}
},
// Stage 2 - group by type & nodeid then get first item found in each group
{
$group: {
"_id":{type:"$type",nodeid:"$nodeid"},
"sensors": {"$first":"$$CURRENT"} //consider using $last if your collection is on reverse
}
},
// Stage 3 - project the fields in desired
{
$project: {
"_id":"$sensors._id",
"timestamp":"$sensors.timestamp",
"type":"$sensors.type",
"nodeid":"$sensors.nodeid",
"value":"$sensors.value"
}
},
// Stage 4 - group and push it to array sensors
{
$group: {
"_id":{nodeid:"$nodeid"},
"sensors": {"$addToSet":"$$CURRENT"}
}
}
]
as far as I got document structure, there is no need to use $lookup as all data is in readings(values) collection.
Please see proposed solution:
db.readings.aggregate([{
$match : {
nodeid : 681
}
},
{
$group : {
_id : {
type : "$type",
nodeid : "$nodeid"
},
readings : {
$push : {
timestamp : "$timestamp",
value : "$value",
id : "$_id"
}
}
}
}, {
$project : {
_id : "$_id",
readings : {
$slice : ["$readings", -1]
}
}
}, {
$unwind : "$readings"
}, {
$project : {
_id : "$readings.id",
type : "$_id.type",
nodeid : "$_id.nodeid",
timestamp : "$readings.timestamp",
value : "$readings.value",
}
}, {
$group : {
_id : "$nodeid",
sensors : {
$push : {
_id : "$_id",
timestamp : "$timestamp",
value : "$value",
type:"$type"
}
}
}
}
])
and output:
{
"_id" : 681,
"sensors" : [
{
"_id" : ObjectId("110cc9c6ac55850d5740784e"),
"timestamp" : ISODate("2016-04-09T12:06:46.344Z"),
"value" : 12,
"type" : "foo"
},
{
"_id" : ObjectId("190ac8b6ac55850d5740776e"),
"timestamp" : ISODate("2016-04-12T12:06:46.344Z"),
"value" : 20,
"type" : "bar"
}
]
}
Any comments welcome!
Say I'm acting on a collection of documents that look like this:
{
"_id" : ObjectId("552712c3f92ea17426000ace"),
"product" : "Mobile Safari",
"venue_id" : NumberLong(71540),
"uid" : "dd542fea6b4443469ff7bf1f56472eac",
"ag" : 0,
"promo" : "bc40100abc8d4eb6a0c68f81f4a756c7",
"promo_f" : NumberLong(1),
"brand" : NumberLong(17),
"venue" : "ovation_2480",
"lt" : 0,
"ts" : ISODate("2015-04-10T00:01:07.734Z"),
"evt" : "login",
"mac" : "00:00:00:00:00:00",
"__ns__" : "wifipromo",
"pvdr" : NumberLong(42),
"os" : "iPhone",
"cmpgn" : "fc6de34aef8b4f57af0b8fda98d8c530",
"ip" : "192.119.43.250",
"lng" : 0,
"product_ver" : "8"
}
I want to count the total amount of aggregate documents with the same uid.
I use this:
db.events_2015_04_10.aggregate([
{
$group: {
_id: "$uid",
count: {
$sum: 1
}
}
}
]);
But lets say I want only a list of aggregations that don't contain evt: "login." In short I only want to aggregate by uid only if all documents with that uid do not have evt: "login."
how would I do that?
You were almost there. Use $match with the $ne operator.
db.events_2015_04_10.aggregate([
{ "$match": { "evt": { "$ne": "login" }}},
{ "$group": { "_id": "$uid", "count": { "$sum": 1 }}}
])