Delete a child record from a specific parent record - mongodb

Question

I am pretty new to mongodb. I have 3 levels of documents.
Parent > Child > Child, all having _id field.
{
"_id" : "n2qw5sojs4bajrj",
"Title" : "Mr",
"Instance" : "HQ",
"FirstName" : "ppp",
"LastName" : "uuuu",
"Position" : "BF",
"EmailAddress" : "xxx#ppp.com",
"Requests" : [
{
"_id" : "121",
"Date" : "12/02/2018",
"Status" : "New",
"ApprovedBy" : {
"_id" : "sdfsdf",
"Name" : "MAN"
},
"PPE" : [
{
"_id" : "121",
"Code" : "PPE",
"Status" : "New",
"Title" : "Trousers",
"Type" : "STD",
"Size" : "10111116",
"Qty" : 1,
"LostDamage" : {
"Reason" : "asdaD",
"Location" : "Station",
"Damage" : "Damged"
}
},
{
"_id" : "122",
"Code" : "PPEOPP",
"Status" : "New",
"Title" : "TrousASDASDASDers",
"Type" : "STD",
"Size" : "10111116",
"Qty" : 1,
"LostDamage" : {
"Reason" : "asdaD",
"Location" : "Station",
"Damage" : "Damged"
}
}
]
}
]
}
I would like find out how to delete the last PPE Element (Parent > Request > PPE) by the _id column.
So I would to delete the following child:
{
"_id" : "121",
"Code" : "PPE",
"Status" : "New",
"Title" : "Trousers",
"Type" : "STD",
"Size" : "10111116",
"Qty" : 1,
"LostDamage" : {
"Reason" : "asdaD",
"Location" : "Station",
"Damage" : "Damged"
}
}
Any tips / help would be great.
Thanks
Paul

Answer 1

You can use MongoDb $pop to remove your last element from array. Like this go to https://docs.mongodb.com/manual/reference/operator/update/pop/
db.collection.update({id:1}, { $pop:{ 'request.PPE':1}});