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How to aggregate array documents in MongoDB?
For this, use the aggregate framework. Let us first create a collection with documents −
> db.aggregateArrayDemo.insertOne(
{
"_id":100,
"UserDetails": [
{
"UserName": "John",
"UserLoginYear":2010
},
{
"UserName": "Carol",
"UserLoginYear":2019
}
]
}
);
{ "acknowledged" : true, "insertedId" : 100 }Following is the query to display all documents from a collection with the help of find() method −
> db.aggregateArrayDemo.find().pretty();
This will produce the following output −
{
"_id" : 100,
"UserDetails" : [
{
"UserName" : "John",
"UserLoginYear" : 2010
},
{
"UserName" : "Carol",
"UserLoginYear" : 2019
}
]
}Following is the query to aggregate array documents −
> db.aggregateArrayDemo.aggregate([
{
$match: { _id: 100 }
},
{
$project: {
Minimum: { $min: "$UserDetails.UserLoginYear" },
Maximum: { $max: "$UserDetails.UserLoginYear" }
}
}
]);This will produce the following output −
{ "_id" : 100, "Minimum" : 2010, "Maximum" : 2019 }
Updated on: 30-Jul-2019
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