Pushing objects on a specific multidimensional mongoDb collection - arrays

Question

i'm fairly new to the mongoDb query language and I'm struggeling with following scenario.
We have a multidimensional dataset that is comprised of:
n users
n projects for each users
n time_entries for each project
What I am trying to achieve is: I would like to push/update a time_entry of a specific project using a collection.update.
Note each pid should be unique for a user
The collection structure I am using looks as follows:
{
"_id" : ObjectId("5d6e33987f8d7f00c063ceff"),
"date" : "2019-01-01",
"users" : [
{
"user_id" : 1,
"projects" : [
{
"pid" : 1,
"time_entries" : [
{
"duration" : 1,
"start" : "2019-08-29T09:54:56+00:00"
}
]
},
{
"pid" : 2,
"time_entries" : []
}
]
},
{
"user_id" : 2,
"projects" : [
{
"pid" : 3,
"time_entries" : []
}
]
}
]
}
I'm currently able to update all projects of a given user using:
"users.$.projects.$[].time_entries"
yet I'm not able to target a specific project, due to the fact the structure contains 2 nesting levels and using multiple $ positional operator is not yet permitted in MongoDb.
"users.$.projects.$.time_entries"
Below is my full query example:
db.times.update(
{ 'users' : { $elemMatch : { 'projects' : { $elemMatch : { 'pid' : 153446871 } } } } },
{ "$push":
{
"users.$.projects.$[].time_entries":
{
"duration" : 5,
"start" : "2019-08-29T09:54:56+00:00"
}
}
}
);
Are there other ways to achieve the same result?
Should I flatten the array so I only use 1 $ positional operator?
Are there other methods to push items on a multidimensional array?
Should this logic be handled on a code level and not a Database level?

Answer 1

You'll need to use the Positional Filtered Operator to achieve that:
db.times.update(
{},
{
$push: {
"users.$[].projects.$[element].time_entries":{
"duration" : 5,
"start" : "2019-08-29T09:54:56+00:00"
}
}
},
{
arrayFilters: [{"element.pid":1}],
multi: true
}
)
This query will push data to the array time_entries for every pid = 1 it finds.
This will give you the result below:
{
"_id" : ObjectId("5d6e33987f8d7f00c063ceff"),
"date" : "2019-01-01",
"users" : [
{
"user_id" : 1,
"projects" : [
{
"pid" : 1,
"time_entries" : [
{
"duration" : 1,
"start" : "2019-08-29T09:54:56+00:00"
},
{
"duration" : 5.0,
"start" : "2019-08-29T09:54:56+00:00"
}
]
},
{
"pid" : 2,
"time_entries" : []
}
]
},
{
"user_id" : 2,
"projects" : [
{
"pid" : 3,
"time_entries" : []
}
]
}
]
}