Querying nested object using $find by applying conditions in Mongodb - node.js

Question

This is my json object
{
"account_id" : "1",
"sections" : [
"name" : "sec1",
"label" : {
"label1" : "text1",
"label2" : "text2"
}
},
"name" : "sec2",
"label" : {
"label3" : "text3",
"label4" : "text4",
"label5" : "text5"
}
},
]
}
So in this json I wanted to query the label object where sector= sec1. I have used the below code but it didn't work.
var getData = (db, query) => {
return db
.collection(TABLE_NAME)
.find(query, { account_id: { sections: { label: 1 } } })
.toArrayAsync();
};
var dataList = (db, event) => {
let dataQuery = {
account_id: id,
'sections.name': event.params.section
};
return getData(db, dataQuery);
};
module.exports.getData = (event, cb) => {
return using(connectDatabase(), db => {
return dataList (db, event);
}).then(data => cb(null, responseObj(data, 200)), err =>
cb(responseObj(err, 500)));
};
Could someone kindly help me? Thanks inadvance.

Answer 1

Try something like this. use $project, we can selectively remove or retain field and we can reassign existing field values and derive entirely new values. after projecting the labels and name do a $match to extract the document by name. One thing to notice is that by using $project,it will automatically assign the document's _id.
var dataList = (db, event) => {
return db
.collection(TABLE_NAME)
.aggregate([
{
$match: { account_id: your_id }
},
{
$unwind: '$sections'
},
{
$project:{labels:'$sections.label',name:'$sections.name'}
},
{
$match:{name:section_name}
}]).toArray();
};

Answer 2

You have to use aggregate method with $unwind syntax to find item in array of object.
var dataList = (db, event) => {
return db
.collection(TABLE_NAME)
.aggregate([
{
$match: {
account_id: id,
}
},
{ $unwind: "$comments" },
{
$match: {
'name': event.params.section
}
}
])
.toArrayAsync();
};
Result:
[{
"account_id": "1",
"sections": {
"name": "sec2",
"label": {
"label3": "text3",
"label4": "text4",
"label5": "text5"
}
}
}]