I want to delete an array from a 2d array from my mongoDB collection. My Schema looks like:
{
"_id" : ObjectId("6218e63e4f9e4efbb05de2bf"),
"name" : "Toyota",
"rate" : 50,
"fine" : 5,
"datesBooked" : [
[
"2022-02-08",
"2022-02-14"
],
[
"2022-02-16",
"2022-02-18"
],
[
"2022-02-20",
"2022-02-22"
],
[
"2022-02-24",
"2022-02-25"
],
[
"2022-03-01",
"2022-03-02"
],
[
"2022-03-01",
"2022-03-02"
]
],
"__v" : 0
}
I would like to find an object with a certain _id and delete a particular element from the datesBooked 2d array. I tried using $pull function but I couldn't get it right. Can someone please tell me how should I be doing this! I'm using express and javascript to do this. Also, I am noob. Already grateful thanks!
This is how to remove particular element from the 2nd array inside datesBooked array via $pull:
var myVariable="2022-02-14"
db.collection.update({ "_id": ObjectId("6218e63e4f9e4efbb05de2bf") },
{
"$pull": {
"datesBooked.$[]": myVariable
}
})
Explained: You need to use the all positional operator $[] ( available since mongodb v3.6) to provide the 2nd array to the $pull operation so it remove the array element with the exact value , in the example this is value "2022-02-14"
If you need to remove the element with [var1,var2] from first array you need to do with $pull like this:
db.collection.update({
"_id": ObjectId("6218e63e4f9e4efbb05de2bf")
},
{
"$pull": {
"datesBooked": [
"2022-02-08",
"2022-02-14"
]
}
})
explained: Pull the array element from the first array
in Mongodb v4.2+ you can use pipelined updates to achieve this, like so:
db.collection.updateOne(
{ _id: id },
[
{
$set: {
datesBooked: {
$concatArrays: [
{
$slice: [
"$datesBooked",
index
]
},
{
$slice: [
"$datesBooked",
index + 1,
{
$size: "$datesBooked"
}
]
}
]
}
}
}
])
For older versions this cannot be done in 1 call, you will need to split this into 2 calls separate calls.
-------------------------- EDIT ------------------------------- Here's how to do it with variables:
const var1 = "2022-02-20";
const var2 = "2022-02-22";
db.collection.updateOne(
{ _id: id },
[
{
$set: {
datesBooked: {
$filter: {
input: "$datesBooked",
cond: {
$and: [
{
$ne: [
{
$arrayElemAt: [
"$$this",
0
]
},
var1
]
},
{
$ne: [
{
$arrayElemAt: [
"$$this",
1
]
},
var2
]
}
]
}
}
}
}
}
])