Meteor MongoDB return single object - mongodb

Question

{
"_id" : "R9zbu8oTWwgxT5eCR",
"practiceSetup" : {
"operatoriesSettings" : [
{
"name" : "Operatory 1",
"description" : "Room 1",
"status" : true
},
{
"name" : "Operatory 2",
"description" : "Room B",
"status" : true
}
],
}
I'm trying to lookup object that has name "Operatory 1" and only return that object.
Here is what I have tried,
Practice.findOne({ _id: 'R9zbu8oTWwgxT5eCR' }, { "$elemMatch": { "practiceSetup.operatoriesSettings": { "name": "Operatory 1" } } } );
However this will return the whole document, not that particular object, not sure what I'm doing wrong here.

Answer 1

You can try out this,
Practice.findOne({ _id: 'R9zbu8oTWwgxT5eCR' }).map(function(u){
return u.practiceSetup
.operatoriesSettings
.filter( m => m.name == "Operatory 1");
})
This will return:
[
[
{
"name" : "Operatory 1",
"description" : "Room 1",
"status" : true
}
]
]

Answer 2

That's how $elemMatch projection works:
The $elemMatch operator limits the contents of an field from the query results to contain only the first element matching the $elemMatch condition.
If you only need that specific subdocument, you get it using JS:
const doc = Practice.findOne(
{ _id: 'R9zbu8oTWwgxT5eCR' },
{
$elemMatch: {
'practiceSetup.operatoriesSettings': {
name: 'Operatory 1'
}
}
}
);
const operator1 = doc.practiceSetup.operatoriesSettings[0];

Answer 3

I found that using "Projections" will return matched object off an array.
Query:
{ "_id": "R9zbu8oTWwgxT5eCR", "practiceSetup.operatoriesSettings": { $elemMatch: {'name': 'Operatory 1'} } }
Projection
{"practiceSetup.operatoriesSettings.$.name": 1}
Full Query:
db.Practice.findOne({
"_id" : "R9zbu8oTWwgxT5eCR",
"practiceSetup.operatoriesSettings" : {
"$elemMatch" : {
"name" : "Operatory 1"
}
}
}, {
"practiceSetup.operatoriesSettings.$.name" : 1.0
});
Returns
{
"_id" : "R9zbu8oTWwgxT5eCR",
"practiceSetup" : {
"operatoriesSettings" : [
{
"name" : "Operatory 1",
"description" : "Room 1",
"status" : true
}
]
}
}
Meteor
When using Meteor methods, you will need to use "fields" when using Projections.
return Practice.findOne({
"_id": "R9zbu8oTWwgxT5eCR",
"practiceSetup.operatoriesSettings": {
"$elemMatch": {
"name": data
}
}
},
{ fields: { 'practiceSetup.operatoriesSettings.$.name': 1, _id: 0 } }
);