I successfully thanks to the help of the people here managed to $lookup two IDs in my document with their representive document in another collection. The next step I need to take is to further lookup a "nested" ID (refering to a document in another collection).
I tried to simply put another $lookup pipeline up but that just worked part-wise.
So it happens that an "empty" document was included into the chieftain attributes and all other attributes of chieftain where somewhat removed.
See my current aggregate:
db.getCollection('village').aggregate([
{
"$match": { _id: "111" }
},
{
"$lookup": {
from: "character",
localField: "chieftainId",
foreignField: "_id",
as: "chieftain"
}
},
{
"$lookup": {
from: "character",
localField: "villagerIds",
foreignField: "_id",
as: "villagers"
}
},
{
"$lookup": {
from: "bloodline",
localField: "chieftain.bloodline",
foreignField: "_id",
as: "chieftain.bloodline"
}
},
{ "$project" : { "villagerIds" : 0, "chieftainId" : 0}},
{ "$unwind" : "$chieftain" }
])
The result of that is the following:
{
"_id" : "111",
"name" : "MyVillage",
"reputation" : 0,
"chieftain" : {
"bloodline" : []
},
"villagers" : [
{
"_id" : "333",
"name" : "Bortan",
"age" : 21,
"bloodlineId" : "7f02191f-90af-406e-87ff-41d5b4387999",
"villageId" : "foovillage",
"professionId" : "02cbb10a-6c0f-4249-a932-3f40e12d32c5"
},
{
"_id" : "444",
"name" : "Blendi",
"age" : 21,
"bloodlineId" : "b3a8ffeb-27aa-4e2e-a8e6-b382554f326a",
"villageId" : "foovillage",
"professionId" : "45dc9350-c84a-491d-a49a-524834dd5773"
}
]
}
I expected the chieftain part to look like this (this is how the chieftain document looks like without the 'last' $lookup I added):
"chieftain" : {
"_id" : "222",
"name" : "Bolzan",
"age" : 21,
"bloodlineId" : "7c2926f9-2f20-4ccf-846a-c9966970fa9b", // this should be resolved/lookedup
"villageId" : "foovillage",
},
At the point of the lookup, chieftan is an array, so setting the chieftan.bloodline replaces the array with an object containing only the bloodline field.
Move the { "$unwind" : "$chieftain" } stage to before the bloodline lookup stage so the lookup is dealing with an object.
Related
Im trying to populate the second nested array after using aggregate $lookup.
This is my original array.
{
"_id" : ObjectId("607da9c0c7cb26384c7810a6"),
"date" : ISODate("2021-04-20T00:00:00.000+0000"),
"clientID" : "601e6dc61766587af8ce76db",
"medications" : [
{
"_id" : ObjectId("6065de3aa95e721f587f7528")
},
]
}
{
from: "medications",
localField: "medications._id",
foreignField: "_id",
as: "medications",
}
after using aggregate $lookup I get this result, but I still have nested array "inventory" that I need to populate. I tried adding another $lookup pipeline, but I don't know how the right way to do that.
{
"_id" : ObjectId("607da9c0c7cb26384c7810a6"),
"date" : ISODate("2021-04-20T00:00:00.000+0000"),
"clientID" : "601e6dc61766587af8ce76db",
"medications" : {
"_id" : ObjectId("6065de3aa95e721f587f7528"),
"medication": "med 1"
"schedule": ["9am", "10pm"]
"inventory": "ObjectId("6076d55ab6aeb947dca85877")"
}
}
This is the inventory item
{
"_id" : ObjectId("6076d55ab6aeb947dca85877"),
"item": "Inventory item 1",
"Qty": "10"
}
Expected Output
{
"_id" : ObjectId("607da9c0c7cb26384c7810a6"),
"date" : ISODate("2021-04-20T00:00:00.000+0000"),
"clientID" : "601e6dc61766587af8ce76db",
"medications" : {
"_id" : ObjectId("6065de3aa95e721f587f7528"),
"medication": "med 1"
"schedule": ["9am", "10pm"]
"inventory": {
"_id" : ObjectId("6076d55ab6aeb947dca85877"),
"item": "Inventory item 1",
"Qty": "10"
}
}
}
You can try this one or alternatively use population.
{
from: "medications",
localField: "medications._id",
foreignField: "_id",
as: "medications",
}
, {
$unwind: {
path: "$medications",
preserveNullAndEmptyArrays: true
}
}, {
$lookup: {
from: "inventory",
localField: "inventory._id",
foreignField: "_id",
as: "medications.inventory",
}
}
You may check the $unwind in the official documentation. Just pay attention to the appropriate localField and foreignField.
use populate() to expand nested references.
schemaModel.populate(result, {path: 'result'});
See more at Mongoose docs
I have three collections in EmployeeDB.
Employee
{
"user_id" : "EMP001",
"FirstName" : "Manoj",
"LastName" : "sharma",
"Status" : "0/1",
"CreateDate" : "1988-10-11T18:30:00.000Z"
}
EmpContact
{
"user_id" : "EMP001",
"Phone" : "9999999999",
"Email" : "xyz#gmail.com"
}
EmpInfo
{
"user_id" : "EMP001",
"Gender" : "Male",
"Age" : NumberInt(20),
"Designation" : "manager",
"Salary" : "5000"
}
I need to group the three collections and display all fields.
I tried the below code,
db.Employee.aggregate([
{$lookup: {from: "EmpContact",localField: "user_id",foreignField: "user_id",as: "contact"}},
{$unwind:"$EmpContact"},
{$lookup: {from: "EmpInfo",localField: "user_id",foreignField: "user_id",as: "empinfo"}},
{$unwind:"$EmpInfo"},
{
$match:{user_id : "EMP001"}
}
]).toArray();
But I got an empty array, Please help me...
The problem comes from your $unwind.
Since you name your field as contact in the $lookup, the field EmpContact doesn't exist.
The same thing for the second unwind, EmpInfo doesn't exist but empinfo does
Here is the full query
db.Employee.aggregate([
{
$lookup: {
from: "EmpContact",
localField: "user_id",
foreignField: "user_id",
as: "contact"
}
},
{
$unwind: "$contact"
},
{
$lookup: {
from: "EmpContact",
localField: "user_id",
foreignField: "user_id",
as: "empinfo"
}
},
{
$unwind: "$empinfo"
},
{
$match: {
user_id: "EMP001"
}
}
])
Try it here
I have two collections:
user:
{
"_id" : "9efb42e5-514d-44bd-a4b8-6f74e6313ec2",
"name" : "Haralt",
"age" : 21,
"bloodlineId" : "c59a2d02-f304-49a8-a52a-44018fc15fe6",
"villageId" : "foovillage"
}
bloodlines:
{
"_id" : "c59a2d02-f304-49a8-a52a-44018fc15fe6",
"name" : "Tevla",
"legacy" : 0
}
Now I'd like to do an aggregate to replace user.bloodlineId with the whole bloodline document.
This is what I tried to far:
db.getCollection('character').aggregate([
{
"$match": { _id: "9efb42e5-514d-44bd-a4b8-6f74e6313ec2" }
},
{
"$lookup": {
from: "bloodline",
localField: "bloodlineId",
foreignField: "_id",
as: "bloodline"
}
}])
The result is almost where I want it:
{
"_id" : "9efb42e5-514d-44bd-a4b8-6f74e6313ec2",
"name" : "Haralt",
"age" : 21,
"bloodlineId" : "c59a2d02-f304-49a8-a52a-44018fc15fe6",
"villageId" : "foovillage",
"bloodline" : [
{
"_id" : "c59a2d02-f304-49a8-a52a-44018fc15fe6",
"name" : "Tevla",
"legacy" : 0
}
]
}
Only two issues here. The first is that bloodlineId is still there and bloodline was just added to the result. I'd like to have bloodline replace the bloodlineId attribute.
The second problem is that bloodline is an array. I'd love to have it a single object.
I think this pipeline might do the trick:
[
{
"$match": {
_id: "9efb42e5-514d-44bd-a4b8-6f74e6313ec2"
}
},
{
"$lookup": {
from: "bloodlines",
localField: "bloodlineId",
foreignField: "_id",
as: "bloodline"
}
},
{
$project: {
"age": 1,
"bloodlineId": {
$arrayElemAt: [
"$bloodline",
0
]
},
"name": 1,
"villageId": 1
}
}
]
Mongo Playground
If there's anything I'm missing, please let me know!
I was trying to join multiple collections in MongoDB using the aggregate $lookup.The issue I am facing right now $lookup localField attribute does not accept $ character.
I have following three collections.
student
{
"_id" : ObjectId("5db12e6dfc368dff1cfc30e5"),
"studentId" : "S97YAREA51",
"name" : "Has Maara duwa",
"age" : 22
}
course
{
"_id" : ObjectId("5db12e6dfc368dff1cfc20e5"),
"courseId" : "C04865690",
"courseName" : "Love and Empathy"
}
studentCourse
{
"_id" : ObjectId("5db12e6dfc368dff1cfc10e5"),
"student" : {
"$ref" : "student",
"$id" : ObjectId("5db12e6dfc368dff1cfc30e5")
},
"course" : {
"$ref" : "course",
"$id" : ObjectId("5db12e6dfc368dff1cfc20e5")
}
}
I need to update studentCourse collection records to something like below.
{
"_id" : ObjectId("5db12e6dfc368dff1cfc10e5"),
"student" : {
"$ref" : "student",
"$id" : ObjectId("5db12e6dfc368dff1cfc30e5")
},
"course" : {
"$ref" : "course",
"$id" : ObjectId("5db12e6dfc368dff1cfc20e5")
},
"studentId" : "S97YAREA51",
"courseId" : "C04865690"
}
I tried to create the following aggregation query, but it was failing due to localField does not accept $ character. I would be much appreciated if somebody provides me a simple solution for this matter.
db.studentCourse.aggregate([
{
$lookup:{
from: "student",
localField: "student.$id",
foreignField: "_id",
as: "student"
}
},
{ $unwind:"$student" }, // $unwind used for getting data in object or for one record only
{
$lookup:{
from: "course",
localField: "course.$id",
foreignField: "_id",
as: "course"
}
},
{ $unwind:"$course" },
// define which fields are you want to fetch
{
$project:{
"_id" : 1,
"student" : 1,
"course" : 1,
"studentId" : "$student.studentId",
"courseId" : "$course.courseId",
}
}
]);
I have two collections - orders, feedback
Orders:
{
"restaurantId" : NumberInt(138),
"referenceNo" : "1980DBF5",
"orderId" : "1045593",
"userId" : NumberInt(6664960),
"userEmail" : "user#g.com",
"firstName" : "User"
}
Feedbacks:
{
"rating" : NumberInt(4),
"additionalComments" : "it is working",
"referenceNo" : "7D02097F",
"productId" : NumberInt(1),
"restaurantId" : NumberInt(138),
"orderType" : "1"
}
I need to make a join on these two collections.
Also, there will be filter inputs on rating, referenceNo, userEmail, firstName.
How can I use match to get data from two collections?
This is my aggregate query:
[
{
"$lookup":
{
"from": "orders",
"localField": "referenceNo",
"foreignField": "referenceNo",
"as": "data"
}
}
]
I am using this query on feedback model.
The data that I get is:
{
"rating" : NumberInt(4),
"additionalComments" : "it is working",
"referenceNo" : "7D02097F",
"productId" : NumberInt(1),
"restaurantId" : NumberInt(138),
"orderType" : "1"
"data": [{
"restaurantId" : NumberInt(138),
"referenceNo" : "1980DBF5",
"orderId" : "1045593",
"userId" : NumberInt(6664960),
"userEmail" : "user#g.com",
"firstName" : "User"
}]
}
Also, would it be possible to add limits here?
Earlier I was using this on orders -
mQuery.skip(Number(paginate.offset)).limit(Number(paginate.limit));
Check if this helps....
db.feedbacks.aggregate([ {
$lookup:
{
from: "users",
localField: "whatever",
foreignField: "whatever",
as: "data"
}},
{
$unwind: "$data"
},
{
$match:
{
"data.orderId":"1045593"} //conditions
},
{
$limit:1 //limit
}
]);