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Merge two array fields in MongoDB?
To merge, use $setUnion operator. Let us first create a collection with documents −
> db.mergeTwoArrayFieldDemo.insertOne({"NaturalNumbers":[1,2,3,8,10,20,30],"WholeNumbers":[0,1,2,63,78,20,45]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cd68e4057806ebf1256f11d")
}Following is the query to display all documents from a collection with the help of find() method −
> db.mergeTwoArrayFieldDemo.find().pretty();
This will produce the following output −
{
"_id" : ObjectId("5cd68e4057806ebf1256f11d"),
"NaturalNumbers" : [
1,
2,
3,
8,
10,
20,
30
],
"WholeNumbers" : [
0,
1,
2,
63,
78,
20,
45
]
}Following is the query to merge two array field in MongoDB.
> db.mergeTwoArrayFieldDemo.aggregate([
{ "$project": {
"MergedArray": { "$setUnion": [ "$NaturalNumbers", "$WholeNumbers" ] }
}}
]);This will produce the following output −
{ "_id" : ObjectId("5cd68e4057806ebf1256f11d"), "MergedArray" : [ 0, 1, 2, 3, 8, 10, 20, 30, 45, 63, 78 ] }
Updated on: 30-Jul-2019
536 Views
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