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How to get only values in arrays with MongoDB aggregate?
Let us create a collection with documents −
> db.demo411.insertOne(
... {
... "Information" : [
... {
... "Name1" : "Chris",
... "Name2" : "David"
... },
... {
... "Name1" : "John",
... "Name2" : "John"
... }
... ]
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5e70f19715dc524f70227682")
}Display all documents from a collection with the help of find() method −
> db.demo411.find();
This will produce the following output −
{ "_id" : ObjectId("5e70f19715dc524f70227682"), "Information" : [ { "Name1" : "Chris", "Name2" : "David" }, { "Name1" : "John", "Name2" : "John" } ] }Following is the query to get only values in arrays −
> db.demo411.aggregate(
... [
... {$project : {
... _id : 0,
... Information : {$map : {input : "$Information", as : "out", in : ["$$out.Name1", "$$out.Name2"]}}
... }
... }
... ]
... )This will produce the following output −
{ "Information" : [ [ "Chris", "David" ], [ "John", "John" ] ] }
Updated on: 03-Apr-2020
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