How to join multiple tables in mongodb - mongodb

Question

I currently have 5 tables that need to joined due to their coupling.
Using $lookup I can join the Order table with the Plan table and get what I need, but how do I go about the other tables?
Here is each table, and the Id/table it needs to connect with
Plan - _id, unassignedOrderIds(array)
DriverPlan - _id, planId, orderIds(array), driverId, vehicleId
Driver - _id, vehicleId
Vehicle - _id
Orders - _id
In the end I'm looking for mongoDb to return a Plan object that has UnassignedOrders loaded and DriverPlans loaded. Followed by DriverPlans having its Orders,Driver, and Vehicle loaded.
Here is what I have so far:
db.Plan.aggregate([
// Unwind the source
{ "$unwind": "$UnassignedOrderIds" },
// Do the lookup matching
{ "$lookup": {
"from": "Order",
"localField": "UnassignedOrderIds",
"foreignField": "_id",
"as": "UnassignedOrders"
}},
// Unwind the result arrays ( likely one or none )
{ "$unwind": "$UnassignedOrders" },
// Group back to arrays
{ "$group": {
"_id": "$_id",
"Order": { "$push": "$Order" },
"UnassignedOrders": { "$push": "$UnassignedOrders" }
}}
])
Sample Document:
//Plan
{
"_id" : ObjectId("5c1d244de707b20cece645f1"),
"UnassignedOrderIds" : [
ObjectId("5c1d247fe707b20cece6462e"),
ObjectId("5c1d035de707b20cece63104")
]
}
//DriverPlan
[{
"_id" : ObjectId("123d247fe707b20cece6462e"),
"PlanId" : ObjectId("5c1d244de707b20cece645f1"),
"DriverId" : ObjectId("1c1d247fe707b20cece64622"),
"VehicleId" : ObjectId("3c1d247fe707b20cece64633"),
"OrderIds": [
ObjectId("5c1d247fe707b20cece64621"),
ObjectId("5c1d247fe707b20cece64624")
]
},{
"_id" : ObjectId("123d247fe707b20cece64655"),
"PlanId" : ObjectId("5c1d244de707b20cece645f1"),
"DriverId" : ObjectId("2c1d035de707b20cece63104"),
"VehicleId" : null,
"OrderIds": [
ObjectId("5c1d247fe707b20cece64625")
]
}]
//Orders
[{
"_id" : ObjectId("5c1d247fe707b20cece6462e"),
"name" "Order1"
},{
"_id" : ObjectId("5c1d035de707b20cece63104"),
"name" "Order2"
},{
"_id" : ObjectId("5c1d247fe707b20cece64621"),
"name" "Order3"
},{
"_id" : ObjectId("5c1d247fe707b20cece64624"),
"name" "Order4"
},{
"_id" : ObjectId("5c1d247fe707b20cece64625"),
"name" "Order5"
}]
//Driver
[{
"_id" : ObjectId("1c1d247fe707b20cece64622"),
"vehicleId" : ObjectId("3c1d247fe707b20cece6462e"),
"name" "Driver1"
},{
"_id" : ObjectId("2c1d035de707b20cece63104"),
"vehicleId" : null,
"name" "Driver2"
},{
"_id" : ObjectId("3c1d247fe707b20cece64621"),
"vehicleId" : ObjectId("3c1d035de707b20cece63104"),
"name" "Driver3"
}]
//Vehicle
[{
"_id" : ObjectId("3c1d247fe707b20cece6462e"),
"name" "Vehicle1"
},{
"_id" : ObjectId("3c1d035de707b20cece63104"),
"name" "Vehicle2"
},{
"_id" : ObjectId("3c1d247fe707b20cece64633"),
"name" "Vehicle3"
}]
The Expected output is json object as follows
//Plan with children loaded
{
"_id" : ObjectId("5c1d244de707b20cece645f1"),
"UnassignedOrderIds" : [
ObjectId("5c1d247fe707b20cece6462e"),
ObjectId("5c1d035de707b20cece63104")
],
"UnassignedOrders": [{
"_id" : ObjectId("5c1d247fe707b20cece6462e"),
"name" "Order1"
},{
"_id" : ObjectId("5c1d035de707b20cece63104"),
"name" "Order2"
}],
"DriverPlans" :
[{
"_id" : ObjectId("123d247fe707b20cece6462e"),
"PlanId" : ObjectId("5c1d244de707b20cece645f1"),
"DriverId" : ObjectId("1c1d247fe707b20cece64622"),
"Driver": {
"_id" : ObjectId("1c1d247fe707b20cece64622"),
"vehicleId" : ObjectId("3c1d247fe707b20cece6462e"),
"name" "Driver1"
},
"VehicleId" : ObjectId("3c1d247fe707b20cece64633"),
"Vehicle" : {
"_id" : ObjectId("3c1d247fe707b20cece64633"),
"name" "Vehicle3"
},
"OrderIds": [
ObjectId("5c1d247fe707b20cece64621"),
ObjectId("5c1d247fe707b20cece64624")
],
"Orders" : [
{
"_id" : ObjectId("5c1d247fe707b20cece64621"),
"name" "Order3"
},{
"_id" : ObjectId("5c1d247fe707b20cece64624"),
"name" "Order4"
}]
},{
"_id" : ObjectId("123d247fe707b20cece64655"),
"PlanId" : ObjectId("5c1d244de707b20cece645f1"),
"DriverId" : ObjectId("2c1d035de707b20cece63104"),
"Driver" : {
"_id" : ObjectId("2c1d035de707b20cece63104"),
"vehicleId" : null,
"name" "Driver2"
}
"VehicleId" : null,
"Vehicle" : null,
"OrderIds": [
ObjectId("5c1d247fe707b20cece64625")
],
"Orders": [{
"_id" : ObjectId("5c1d247fe707b20cece64625"),
"name" "Order5"
}
]
}]
}

Answer 1

You can use below aggregation
db.Plan.aggregate([
{ "$lookup": {
"from": Order.collection.name,
"let": { "unassignedOrderIds": "$UnassignedOrderIds" },
"pipeline": [
{ "$match": { "$expr": { "$in": ["$_id", "$$unassignedOrderIds"] } } }
],
"as": "UnassignedOrderIds"
}},
{ "$lookup": {
"from": DriverPlan.collection.name,
"let": { "planId": "$_id" },
"pipeline": [
{ "$match": { "$expr": { "$eq": ["$PlanId", "$$planId"] } } },
{ "$lookup": {
"from": Driver.collection.name,
"let": { "driveId": "$DriverId" },
"pipeline": [
{ "$match": { "$expr": { "$eq": ["$_id", "$$driveId"] } } }
],
"as": "Driver"
}},
{ "$lookup": {
"from": Vehicle.collection.name,
"let": { "vehicleId": "$VehicleId" },
"pipeline": [
{ "$match": { "$expr": { "$eq": ["$_id", "$$vehicleId"] } } }
],
"as": "Vehicle"
}},
{ "$lookup": {
"from": Order.collection.name,
"let": { "orderIds": "$OrderIds" },
"pipeline": [
{ "$match": { "$expr": { "$in": ["$_id", "$$orderIds"] } } }
],
"as": "Orders"
}}
],
"as": "DriverPlans"
}}
])
With mongodb 3.4 and below $lookup syntax
db.Plan.aggregate([
{ "$lookup": {
"from": Order.collection.name,
"localField": "UnassignedOrderIds",
"foreignField": "_id",
"as": "UnassignedOrderIds"
}},
{ "$lookup": {
"from": DriverPlan.collection.name,
"localField": "_id",
"foreignField": "PlanId",
"as": "DriverPlans"
}},
{ "$unwind": "$DriverPlans" },
{ "$lookup": {
"from": Driver.collection.name,
"localField": "DriverPlans.DriverId",
"foreignField": "_id",
"as": "DriverPlans.Driver"
}},
{ "$unwind": "$DriverPlans.Driver" },
{ "$lookup": {
"from": Vehicle.collection.name,
"localField": "DriverPlans.VehicleId",
"foreignField": "_id",
"as": "DriverPlans.Vehicle"
}},
{ "$unwind": "$DriverPlans.Vehicle" },
{ "$lookup": {
"from": Order.collection.name,
"localField": "DriverPlans.OrderIds",
"foreignField": "_id",
"as": "DriverPlans.Orders"
}},
{ "$group": {
"_id": "$_id",
"DriverPlans": { "$push": "$DriverPlans" }
}}
])