How to write following queries in MongoDB using aggregate? - mongodb

Question

Retrieve films with an actor living in "Spain",
Retrieve films with actor details.
Collections are:
db.actor.insert([{ "actorId" : "5", "firstName" : "Ritik", "lastName" : "Roshan", "address" : { "street" : "GM Road", "city" : "Guwahati", "state" : "Aasam", "country" : "India", "pincode" : "145145" }, "contactDetails" : { "email" : "Ritik.roshan#gmail.com", "phoneno" : "9874584" }, "age" : "52" }])
db.film.insert([{ "filmId" : "10","title" : "Doshti Ka Karishma", "releaseOfYear" : "2001", "category" : ["advanture","Romantic"],
"actor" : [{ "firstName" : "Ritik", "lastName" : "Roshan" },{ "firstName" : "Karishma", "lastName" : "Kapoor" }],
"director" : [{ "firstName" : "Satish", "lastName" : "Ambike" }],
"releaseDetails" : { "place" : "Rajasthan", "date" : ISODate("2001-05-18T15:14:08.023Z"), "rating" : "C"}}])

Answer 1

You can use $lookup to join two collection
db.film.aggregate([
{ $match: { "releaseDetails.place": "Rajasthan" } },
{
"$lookup": {
"from": "actor",
"let": {
actor: "$actor"
},
"pipeline": [
{
$match: {
$expr: {
$and: [
{ $in: [ "$firstName", "$$actor.firstName" ] },
{ $in: [ "$lastName", "$$actor.lastName" ] }
]
}
}
}
],
"as": "joinActors"
}
}
])
Working Mongo playground
Note : You are saving firstname and lastname as reference in film collection. But combination of firstname and lastname are not always unique, Better you save _id of actor into the film collection's actor section.
something like this Save ref id