Nested array count without unwind? - mongodb

Is it possible to count a nested array without using $unwind in MongoDB? If possible then help me out. My json file is like this:
{
"_id" : ObjectId("57307906f051147d5317984e"),
"user" : [
{
"firstName" : "chetan",
"lastName" : "kumar",
"age" : 23,
"like" : [
{
"bookname" : "mongo"
},
{
"bookname" : "php"
},
{
"bookname" : "java"
}
]
},
{
"firstName" : "nepolean",
"lastName" : "dang",
"age" : 26,
"like" : [
{
"bookname" : "mongo"
},
{
"bookname" : "php"
}
]
},
{
"firstName" : "Raj",
"lastname" : "kumar",
"age" : 26,
"like" : [
{
"bookname" : "mongo"
}
]
}
],
"sales" : [
{
"firstName" : "ashu",
"lastName" : "jha",
"age" : 27
}
]
}
If I use $unwind then I can easily find out the result like this:
db.userdetail.aggregate([
{"$unwind": "$user"},
{"$project": {
"likecount": { "$size": "$user.like" }
}}
]).pretty()
{ "_id" : ObjectId("57307906f051147d5317984e"), "likecount" : 3 }
{ "_id" : ObjectId("57307906f051147d5317984e"), "likecount" : 2 }
{ "_id" : ObjectId("57307906f051147d5317984e"), "likecount" : 1 }

Related

Problems aggregating MongoDB

I am having problems aggregating my Product Document in MongoDB.
My Product Document is:
{
"_id" : ObjectId("5d81171c2c69f45ef459e0af"),
"type" : "T-Shirt",
"name" : "Panda",
"description" : "Panda's are cool.",
"image" : ObjectId("5d81171c2c69f45ef459e0ad"),
"created_at" : ISODate("2019-09-17T18:25:48.026+01:00"),
"is_featured" : false,
"sizes" : [
"XS",
"S",
"M",
"L",
"XL"
],
"tags" : [ ],
"pricing" : {
"price" : 26,
"sale_price" : 8
},
"categories" : [
ObjectId("5d81171b2c69f45ef459e086"),
ObjectId("5d81171b2c69f45ef459e087")
],
"sku" : "5d81171c2c69f45ef459e0af"
},
And my Category Document is:
{
"_id" : ObjectId("5d81171b2c69f45ef459e087"),
"name" : "Art",
"description" : "These items are our artsy options.",
"created_at" : ISODate("2019-09-17T18:25:47.196+01:00")
},
My aim is to perform aggregation on the Product Document in order to count the number of items within each Category. So I have the Category "Art", I need to count the products are in the "Art" Category:
My current aggregate:
db.product.aggregate(
{ $unwind : "$categories" },
{
$group : {
"_id" : { "name" : "$name" },
"doc" : { $push : { "category" : "$categories" } },
}
},
{ $unwind : "$doc" },
{
$project : {
"_id" : 0,
"name" : "$name",
"category" : "$doc.category"
}
},
{
$group : {
"_id" : "$category",
"name": { "$first": "$name" },
"items_in_cat" : { $sum : 1 }
}
},
{ "$sort" : { "items_in_cat" : -1 } },
)
Which does actually work but not as I need:
{
"_id" : ObjectId("5d81171b2c69f45ef459e082"),
"name" : null, // Why is the name of the category no here?
"items_in_cat" : 4
},
As we can see the name is null. How can I aggregate the output to be:
{
"_id" : ObjectId("5d81171b2c69f45ef459e082"),
"name" : "Art",
"items_in_cat" : 4
},

We need to use $lookup to fetch the name from Category collection.
The following query can get us the expected output:
db.product.aggregate([
{
$unwind:"$categories"
},
{
$group:{
"_id":"$categories",
"items_in_cat":{
$sum:1
}
}
},
{
$lookup:{
"from":"category",
"let":{
"id":"$_id"
},
"pipeline":[
{
$match:{
$expr:{
$eq:["$_id","$$id"]
}
}
},
{
$project:{
"_id":0,
"name":1
}
}
],
"as":"categoryLookup"
}
},
{
$unwind:{
"path":"$categoryLookup",
"preserveNullAndEmptyArrays":true
}
},
{
$project:{
"_id":1,
"name":{
$ifNull:["$categoryLookup.name","NA"]
},
"items_in_cat":1
}
}
]).pretty()
Data set:
Collection: product
{
"_id" : ObjectId("5d81171c2c69f45ef459e0af"),
"type" : "T-Shirt",
"name" : "Panda",
"description" : "Panda's are cool.",
"image" : ObjectId("5d81171c2c69f45ef459e0ad"),
"created_at" : ISODate("2019-09-17T17:25:48.026Z"),
"is_featured" : false,
"sizes" : [
"XS",
"S",
"M",
"L",
"XL"
],
"tags" : [ ],
"pricing" : {
"price" : 26,
"sale_price" : 8
},
"categories" : [
ObjectId("5d81171b2c69f45ef459e086"),
ObjectId("5d81171b2c69f45ef459e087")
],
"sku" : "5d81171c2c69f45ef459e0af"
}
Collection: category
{
"_id" : ObjectId("5d81171b2c69f45ef459e086"),
"name" : "Art",
"description" : "These items are our artsy options.",
"created_at" : ISODate("2019-09-17T17:25:47.196Z")
}
{
"_id" : ObjectId("5d81171b2c69f45ef459e087"),
"name" : "Craft",
"description" : "These items are our artsy options.",
"created_at" : ISODate("2019-09-17T17:25:47.196Z")
}
Output:
{
"_id" : ObjectId("5d81171b2c69f45ef459e087"),
"items_in_cat" : 1,
"name" : "Craft"
}
{
"_id" : ObjectId("5d81171b2c69f45ef459e086"),
"items_in_cat" : 1,
"name" : "Art"
}

How to join deeply nested array?

Here is my actual database schema.
company_id is reference object of companies collection and booking_days.consultants.consultant_id is reference object of users collection.
I want to join embedded document with company_id and booking_days.consultants.consultant_id.
{
"_id" : ObjectId("5a7040d664544e1bb877deae"),
"company_id" : ObjectId("5a6eb43f437e6a0d9e00c92f"),
"booking_days" : [
{
"booking_date" : ISODate("2018-01-31T00:00:00.000Z"),
"_id" : ObjectId("5a7040d664544e1bb877deca"),
"consultants" : [
{
"consultant_id" : ObjectId("5a6f2854ce7d6938de1dd52c"),
"_id" : ObjectId("5a7040d664544e1bb877decc")
},
{
"consultant_id" : ObjectId("5a6f2854ce7d6938de1dd52f"),
"_id" : ObjectId("5a7040d664544e1bb877decb")
}
]
},
{
"booking_date" : ISODate("2018-02-01T00:00:00.000Z"),
"_id" : ObjectId("5a7040d664544e1bb877dec6"),
"consultants" : [
{
"consultant_id" : ObjectId("5a6f2854ce7d6938de1dd52f"),
"_id" : ObjectId("5a7040d664544e1bb877dec9")
},
{
"consultant_id" : ObjectId("5a6f2854ce7d6938de1dd52c"),
"_id" : ObjectId("5a7040d664544e1bb877dec8")
},
{
"consultant_id" : ObjectId("5a6f2854ce7d6938de1dd52c"),
"_id" : ObjectId("5a7040d664544e1bb877dec7")
}
]
},
{
"booking_date" : ISODate("2018-02-02T00:00:00.000Z"),
"_id" : ObjectId("5a7040d664544e1bb877dec4"),
"consultants" : [
{
"consultant_id" : ObjectId("5a6f2854ce7d6938de1dd52c"),
"_id" : ObjectId("5a7040d664544e1bb877dec5")
}
]
},
],
"__v" : 0
}
I am using below query.
db.getCollection('booking_days').aggregate(
[
{ $match: { company_id:ObjectId("5a6eb43f437e6a0d9e00c92f") } },
{
$lookup: {
localField: "company_id",
from: "companies",
foreignField: "_id",
as: "companies"
},
},
{
$lookup: {
localField: "booking_days.consultants.consultant_id",
from: "users",
foreignField: "_id",
as: "userssss"
},
},
{
$unwind:"$companies"
},
]
)
Actual Output
{
"_id" : ObjectId("5a7040d664544e1bb877deae"),
"company_id" : ObjectId("5a6eb43f437e6a0d9e00c92f"),
"booking_days" : [
{
"booking_date" : ISODate("2018-01-31T00:00:00.000Z"),
"_id" : ObjectId("5a7040d664544e1bb877deca"),
"consultants" : [
{
"consultant_id" : ObjectId("5a6f2854ce7d6938de1dd52c"),
"_id" : ObjectId("5a7040d664544e1bb877decc")
},
{
"consultant_id" : ObjectId("5a6f2854ce7d6938de1dd52f"),
"_id" : ObjectId("5a7040d664544e1bb877decb")
}
]
},
{
"booking_date" : ISODate("2018-02-01T00:00:00.000Z"),
"_id" : ObjectId("5a7040d664544e1bb877dec6"),
"consultants" : [
{
"consultant_id" : ObjectId("5a6f2854ce7d6938de1dd52f"),
"_id" : ObjectId("5a7040d664544e1bb877dec9")
},
]
},
],
"__v" : 0,
"companies" : {
"_id" : ObjectId("5a6eb43f437e6a0d9e00c92f"),
"first_name" : "Adrienne Runolfsson",
},
"users" : [
{
"_id" : ObjectId("5a6f2854ce7d6938de1dd52c"),
"first_name" : "Christ Hamill",
},
{
"_id" : ObjectId("5a6f2854ce7d6938de1dd52e"),
"first_name" : "Miss Dina Kovacek",
},
]
}
Excepted output. consultant data will come in booking_days.consultants array.
{
"_id" : ObjectId("5a7040d664544e1bb877deae"),
"company_id" : ObjectId("5a6eb43f437e6a0d9e00c92f"),
"booking_days" : [
{
"booking_date" : ISODate("2018-01-31T00:00:00.000Z"),
"_id" : ObjectId("5a7040d664544e1bb877deca"),
"consultants" : [
{
"consultant_id" : {
"_id" : ObjectId("5a6f2854ce7d6938de1dd52c"),
"first_name" : "Christ Hamill",
},
"_id" : ObjectId("5a7040d664544e1bb877decc")
},
{
"consultant_id" : {
"_id" : ObjectId("5a6f2854ce7d6938de1dd52e"),
"first_name" : "Miss Dina Kovacek",
},
"_id" : ObjectId("5a7040d664544e1bb877decb")
}
]
},
{
"booking_date" : ISODate("2018-02-01T00:00:00.000Z"),
"_id" : ObjectId("5a7040d664544e1bb877dec6"),
"consultants" : [
{
"consultant_id" : {
"_id" : ObjectId("5a6f2854ce7d6938de1dd52e"),
"first_name" : "Miss Dina Kovacek",
},
"_id" : ObjectId("5a7040d664544e1bb877dec9")
},
]
},
],
"__v" : 0,
"companies" : {
"_id" : ObjectId("5a6eb43f437e6a0d9e00c92f"),
"first_name" : "Adrienne Runolfsson",
},
}

As such you have to $unwind the localField when it is an embedded document array expect in some cases where localField is an array of scalar ids.
$unwind twice as consultant array is two levels deep followed by $lookup to get the name and $group to get back the expected output.
db.getCollection('booking_days').aggregate([
{"$match":{"company_id":ObjectId("5a6eb43f437e6a0d9e00c92f")}},
{"$lookup":{"localField":"company_id","from":"companies","foreignField":"_id","as":"companies"}},
{"$unwind":"$companies"},
{"$unwind":"$booking_days"},
{"$unwind":"$consultants"},
{"$lookup":{
"localField":"booking_days.consultants.consultant_id",
"from":"users",
"foreignField":"_id",
"as":"booking_days.consultants.consultant_id"
}},
{"$group":{
"_id":{"_id":"$_id","booking_days_id":"$booking_days._id"},
"company_id":{"$first":"$company_id"},
"booking_date":{"$first":"$booking_days.booking_date"},
"companies":{"$first":"$companies"},
"consultants":{"$push":"$booking_days.consultants"}
}},
{"$group":{
"_id":"$_id._id",
"company_id":{"$first":"$company_id"},
"companies":{"$first":"$companies"},
"booking_days":{
"$push":{
"_id":"$_id.booking_days_id",
"booking_date":"$booking_date",
"consultants":"$consultants"
}
}
}}
])

{"Id": "5b87a4c79a9c3feac943fc6c",
"comments" : [
{
"likes" : [],
"_id" : ObjectId("5b87a4c79a9c3feac943fc6c"),
"comment" : "string",
"accountId" : "a426d0da-ac72-4932-828e-3af99a998bc7",
"commentId" : "7d2a05d1-2026-4a13-a5c1-318ed80d1b38",
"reply" : [
{
"_id" : ObjectId("5b87b61e97585ef1d0d22108"),
"comment" : "string",
"accountId" : "a426d0da-ac72-4932-828e-3af99a998bc7",
"replyId" : "ec220fd7-3440-44dc-9178-7a1183879463"
},
{
"_id" : ObjectId("5b87b61e97585ef1d0d22108"),
"comment" : "string klllll",
"accountId" : "a426d0da-ac72-4932-828e-3af99a998bc7",
"replyId" : "ec220fd7-3440-44dc-9178-7a1183879463"
}
]
},
{
"likes" : [],
"_id" : ObjectId("5b87c301c8a07efa2599c29e"),
"comment" : "testing",
"accountId" : "cfd29f53-d73e-480c-9cfa-ea42b4119266",
"commentId" : "0676047b-1712-4f70-89d5-29c1abe03eaf",
"reply" : [
{
"_id" : ObjectId("5b87b61e97585ef1d0d22108"),
"comment" : "string",
"accountId" : "a426d0da-ac72-4932-828e-3af99a998bc7",
"replyId" : "ec220fd7-3440-44dc-9178-7a1183879463"
},
{
"_id" : ObjectId("5b87b61e97585ef1d0d22108"),
"comment" : "string klllll",
"accountId" : "a426d0da-ac72-4932-828e-3af99a998bc7",
"replyId" : "ec220fd7-3440-44dc-9178-7a1183879463"
}
]
}
]
}
accountId is in differnt connection
// Expected Out Put
{"Id": "5b87a4c79a9c3feac943fc6c",
"comments" : [
{
"likes" : [],
"_id" : ObjectId("5b87a4c79a9c3feac943fc6c"),
"comment" : "string",
"name" : "apple",
"reply" : [
{
"_id" : ObjectId("5b87b61e97585ef1d0d22108"),
"comment" : "string",
"name" : "apple",
},
{
"_id" : ObjectId("5b87b61e97585ef1d0d22108"),
"comment" : "string klllll",
"name" : "apple",
}
]
},
{
"likes" : [],
"_id" : ObjectId("5b87c301c8a07efa2599c29e"),
"comment" : "testing",
"name" : "ball",
"reply" : [
{
"_id" : ObjectId("5b87b61e97585ef1d0d22108"),
"comment" : "string",
"name" : "apple",
},
{
"_id" : ObjectId("5b87b61e97585ef1d0d22108"),
"comment" : "string klllll",
"name" : "apple", }
]
}
]
}

MongoDB JsonObject and JsonArray

I'm new MongoDB.
I have a collection is named "surveyCollection".
I insert some data to collection with shell,
db.surveyCollection.insert({
"count":30,
"people": [
{
"firstName":"John",
"lastName":"Jason"
}
]
})
db.surveyCollection.insert({
"count":30,
"people": [
{
"firstName":"Sarah",
"lastName":"Smith"
}
]
})
And I have data below ( db.surveyCollection.find().pretty());
{
"_id" : ObjectId("5873d0c86c3319a579754d00"),
"count" : 30,
"people" : [
{
"firstName" : "John",
"lastName" : "Jason"
}
]
}
{
"_id" : ObjectId("5873d0c86c3319a579754d00"),
"count" : 30,
"people" : [
{
"firstName" : "Sarah",
"lastName" : "Smith"
}
]
}
I don't know how can I insert a new people to any survey. I mean, I want to have datas like below;
{
"_id" : ObjectId("5873d0c86c3319a579754d00"),
"count" : 30,
"people" : [
{
"firstName" : "John",
"lastName" : "Jason"
}
]
}
{
"_id" : ObjectId("5873d0c86c3319a579754d00"),
"count" : 30,
"people" : [
{
"firstName" : "Sarah",
"lastName" : "Smith"
},
{
"firstName" : "George",
"lastName" : "Smith"
}
]
}
I mean, how can I reach values in JsonArray?
Thank you

Use $push method to push an item into array of a document as shown below :
db.surveyCollection.update(
{ "_id" : ObjectId("5873d0c86c3319a579754d00") },
{ $push: { people: { "firstName" : "George", "lastName" : "Smith"} } }
)
This will add the object { "firstName" : "George", "lastName" : "Smith"} to the array people in the document of {"_id" : ObjectId("5873d0c86c3319a579754d00")}

Finding subelements in a document in mongodb

I'm working on the following document
{
"_id" : 123344223,
"firstName" : "gopal",
"gopal" : [
{
"uuid" : "123",
"name" : "sugun",
"sudeep" : [
{
"uuid" : "add32",
"name" : "ssss"
},
{
"uuid" : "fdg456",
"name" : "gfg"
}
]
},
{
"uuid" : "222",
"name" : "kiran"
}
]
}
I want to get my output as following
{
"_id" : 456,
"gopal" : [
{
"uuid" : "123",
"name" : "sugun",
"sudeep" : [
{
"uuid" : "add32",
"name" : "ssss"
}
]
}
]
}
and I tried many things like
db.People.findOne({_id:123},{gopal:{$elemMatch:{uuid:"123",sudeep:{$elemMatch:{uuid:"add32"}}}}});
but whatever I tried it returns the document like this
{
"_id" : 123,
"gopal" : [
{
"uuid" : "123",
"name" : "sugun",
"sudeep" : [
{
"uuid" : "add32",
"name" : "ssss"
},
{
"uuid" : "fdg456",
"name" : "gfg"
}
]
}
]
}
can you please help?

Are you aware of MongoDB aggregation pipeline?
> db.people.aggregate([
{$match: {_id: 123}},
{$unwind: "$gopal"},
{$unwind: "$gopal.sudeep"},
{$match: {"gopal.uuid": "123", "gopal.sudeep.uuid" : "add32"}}
])
Output
{
"_id" : 123,
"firstName" : "gopal",
"gopal" : {
"uuid" : "123",
"name" : "sugun",
"sudeep" : {
"uuid" : "add32",
"name" : "ssss"
}
}
}

Use $unwind in aggregation pipeline
db.People.aggregate([{$match:{_id:'123'}},{$match:{gopal.uuid:'123'}},{$unwind:'$sudeep'},{$match:{uuid:'add32'}}])

MongoDB groupby query

I have colletions containing records like
{ "type" : "me", "tid" : "1" }
{ "type" : "me", "tid" : "1" }
{ "type" : "me", "tid" : "1" }
{ "type" : "you", "tid" : "1" }
{ "type" : "you", "tid" : "1" }
{ "type" : "me", "tid" : "2" }
{ "type" : "me", "tid" : "2"}
{ "type" : "you", "tid" : "2"}
{ "type" : "you", "tid" : "2" }
{ "type" : "you", "tid" : "2"}
I have want result like below
[
{"tid" : "1","me" : 3,"you": 2},
{"tid" : "2","me" : 2,"you": 3}
]
I have tried group and; aggregate queries doesn't get required result format.
below is the group query.
db.coll.group({
key: {tid : 1,type:1},
cond: { tid : { "$in" : [ "1","2"]} },
reduce: function (curr,result) {
result.total = result.total + 1
},
initial: { total : 0}
})
it result is like
[
{"tid" : "1", "type" : "me" ,"total": 3 },
{"tid" : "1","type" : "you" ,"total": 2 },
{"tid" : "2", "type" : "me" ,"total": 2 },
{"tid" : "2","type" : "you" ,"total": 3 }
]
following is aggregate query
db.coll.aggregate([
{$match : { "tid" : {"$in" : ["1","2"]}}},
{$group : { _id : {tid : "$tid",type : "$type"},total : {"$sum" : 1}}}
])
gives following result
{
"result" :
[
{"_id" : {"tid" : "1","type" : "me"},"total" : 3},
{"_id" : {"tid" : "2","type" : "me" },"total" : 2},
{"_id" : {"tid" : "2","type" : "you"},"total" : 3}
]
"ok" : 1
}
it is possible to obtain I specified result or I have to do some manipulation in my code.
Thanks

If you change your aggregation to this:
db.so.aggregate([
{ $match : { "tid" : { "$in" : ["1", "2"] } } },
{ $group : {
_id : { tid : "$tid", type : "$type" },
total : { "$sum" : 1 }
} },
{ $group : {
_id : "$_id.tid",
values: { $push: { type: "$_id.type", total: '$total' } }
} }
])
Then your output is:
{
"result" : [
{
"_id" : "1",
"values" : [
{ "type" : "you", "total" : 2 },
{ "type" : "me", "total" : 3 }
]
},
{
"_id" : "2",
"values" : [
{ "type" : "me", "total" : 2 },
{ "type" : "you", "total" : 3 }
]
}
],
"ok" : 1
}
Although that is not the same as what you want, it is going to be the closest that you can get. And in your application, you can easily pull out the values in the same was as with what you would like to get out of it.
Just keep in mind, that in general you can not promote a value (you, me) to a key — unless your key is of a limited set (3-4 items max).