I have a collection with: I want to use the $in operator
Person = {
name: String,
members: [ {id: String, email: String}... {}]
}
I use this so far:
Person.find({members: {"$in": [id1]}})
But I already know the flaw: If the array of members was like Members: [id1, id2, ... id3] that method would work. But it is an array of objects. So how do I get around it?
$elemMatch can be used with Arrays of Embedded Documents:
In your case you could try:
Person.find({
members: {
$elemMatch: { id: id1 }
}
});
But since it is a Single Query Condition:
Person.find({
"members.id": id1
});
Would do the trick.
You can use members.id as field in your query to match your subdocument ids :
Person.find({ "members.id": { "$in": ["id1"] } })
You can use elem match in the following way:
db.collection.find({
arrayfield: {
$elemMatch: {
id: ObjectId("5eaaeedd00101108e1123461")
}
}
})
The same can be done in mongoose in the following ways:
query.elemMatch('arrayfield', { id: ObjectId("5eaaeedd00101108e1123461") })
.
query.where('arrayfield').elemMatch({ id: ObjectId("5eaaeedd00101108e1123461") })
.
query.elemMatch('arrayfield', function (elem) {
elem.where('id').equals(ObjectId("5eaaeedd00101108e1123461"));
})
.
query.where('arrayfield').elemMatch(function (elem) {
elem.where({ id: ObjectId("5eaaeedd00101108e1123461") });
})
I have used this example collection:
[
{
"_id": ObjectId("5eaaeedd00101108e1123451"),
"arrayfield": [
{
id: ObjectId("5eaaeedd00101108e1123461"),
name: "David"
},
{
id: ObjectId("5eaaeedd00101108e1123462"),
name: "Brown"
}
]
},
{
"_id": ObjectId("5eaaeedd00101108e1123452"),
"arrayfield": [
{
id: ObjectId("5eaaeedd00101108e1123471"),
name: "Maple"
},
{
id: ObjectId("5eaaeedd00101108e1123472"),
name: "Green"
}
]
},
{
"_id": ObjectId("5eaaeedd00101108e1123453"),
"arrayfield": [
{
id: ObjectId("5eaaeedd00101108e1123461"),
name: "David"
},
{
id: ObjectId("5eaaeedd00101108e1123482"),
name: "Lacey"
}
]
}
]
Want to try live? Try it on mongo playground with this link https://mongoplayground.net/p/H3fdmp9HkQv
