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MongoDB projection result as an array of selected items?
Let us create a collection with documents −
> db.demo151.insertOne({"ListOfNames":["Chris","David","Mike"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e3513b6fdf09dd6d08539da")
}
> db.demo151.insertOne({"ListOfNames":["Mike","Bob"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e3513c4fdf09dd6d08539db")
}
> db.demo151.insertOne({"ListOfNames":["John","David","Chris"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e3513dcfdf09dd6d08539dc")
}Display all documents from a collection with the help of find() method −
> db.demo151.find();
This will produce the following output −
{ "_id" : ObjectId("5e3513b6fdf09dd6d08539da"), "ListOfNames" : [ "Chris", "David", "Mike" ] }
{ "_id" : ObjectId("5e3513c4fdf09dd6d08539db"), "ListOfNames" : [ "Mike", "Bob" ] }
{ "_id" : ObjectId("5e3513dcfdf09dd6d08539dc"), "ListOfNames" : [ "John", "David", "Chris" ] }Following is the query to projection result as an array of selected items −
> db.demo151.distinct('_id', {'ListOfNames' : "Mike"});This will produce the following output −
[
ObjectId("5e3513b6fdf09dd6d08539da"),
ObjectId("5e3513c4fdf09dd6d08539db")
]
Updated on: 01-Apr-2020
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