MongoDb: Find exact array match with duplicates - mongodb

Question

m trying to write a mongoDB query to find documents matching given example:
I have collection of users
{
"userId": "1",
"visitedPlaces": [
{
"city": "Kair",
"country": "Egypt"
},
{
"city": "Paris",
"country": "France"
},
{
"city": "Kair",
"country": "Egypt"
},
]
},
{
"userId": "2",
"visitedPlaces": [
{
"city": "Kair",
"country": "Egypt"
},
{
"city": "Paris",
"country": "France"
},
{
"city": "Paris",
"country": "France"
}
]
}
I want to write a query that will return me users which visited 'Kair' twice and 'Paris' once (user "2" is not matching this case)
I have tried query like
.find({"visitedPlaces.city": { "$all": ["Kair", "Paris", "Kair"] }, "visitedPlaces": { "$size": 3 } })
but it returns both users.
Is there a way to write such query in mongo ?

Answer 1

what about this one
db.getCollection('vists').aggregate([{
'$addFields': {
'countVisitedPlaces': {
'$map': {
'input': { '$setUnion': ['$visitedPlaces.city']},
'as': 'city',
'in': {
'city': '$$city',
'noOfTimeCityVists': {
'$size': {
'$filter': {
'input': '$visitedPlaces',
'as': 'visitedCity',
'cond': { '$eq': ['$$visitedCity.city', '$$city'] }
}
}
}
}
}
}
},
// here you got city wise visits count
{
$match: {
$and: [{
'countVisitedPlaces': {
'$elemMatch': {'noOfTimeCityVists': 2, 'city': 'Kair'}
}},
{
'countVisitedPlaces': {
'$elemMatch': {'noOfTimeCityVists': 1, 'city': 'Paris'}
}}
]}
}])
You change last stag of pipeline for different differnt search and your result.

Answer 2

Check the below query. You just need to modify $match depending on your condition.
db.collection.aggregate({
"$unwind": "$visitedPlaces"
},
{
"$group": {
"_id": {
"userId": "$userId",
"city": "$visitedPlaces.city"
},
"count": {
"$sum": 1
}
}
},
{
"$project": {
"userId": "$_id.userId",
"cityCount": {
"city": "$_id.city",
"count": "$count"
},
"_id": 0
}
},
{
"$group": {
"_id": "$userId",
"cityCount": {
"$push": "$cityCount"
}
}
},
{
"$match": {
"cityCount": {
"$all": [
{
"$elemMatch": {
"city": "Kair",
"count": 2
}
},
{
"$elemMatch": {
"city": "Paris",
"count": 1
}
}
]
}
}
},
{
"$project": {
"userId": "$_id",
"_id": 0
}
})
Here is MongoPlayground for you.