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MongoDB query to limit the returning values of a field?
For this, use $slice. Let us create a collection with documents −
> db.demo594.insertOne(
... {
... id:1,
... details:[
... {Name:"Chris",Age:21},
... {Name:"Bob",Age:20},
... {Name:"David",Age:23},
... {Name:"Sam",Age:22}
... ]
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5e933459fd2d90c177b5bcdd")
}Display all documents from a collection with the help of find() method −
> db.demo594.find();
This will produce the following output −
{ "_id" : ObjectId("5e933459fd2d90c177b5bcdd"), "id" : 1, "details" : [
{ "Name" : "Chris", "Age" : 21 },
{ "Name" : "Bob", "Age" : 20 },
{ "Name" : "David", "Age" : 23 },
{ "Name" : "Sam", "Age" : 22 }
] }Following is the query to limit the returning values of a field −
> db.demo594.find({}, {"Name": 1, "details": { "$slice": 1}});This will produce the following output −
{ "_id" : ObjectId("5e933459fd2d90c177b5bcdd"), "details" : [
{ "Name" : "Chris", "Age" : 21 }
] }
Updated on: 15-May-2020
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