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Specify a return format for data in MongoDB
Take the help of $addToSet in MongoDB to specify a return format. Let us create a collection with documents −
> db.demo207.insertOne({"FavouriteTechnology":"Spring Boot"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e3d8e7a03d395bdc21346f1")
}
> db.demo207.insertOne({"FavouriteTechnology":"MongoDB"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e3d8e8f03d395bdc21346f2")
}
> db.demo207.insertOne({"FavouriteTechnology":"Groovy"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e3d8ea603d395bdc21346f3")
}Display all documents from a collection with the help of find() method −
> db.demo207.find();
This will produce the following output −
{ "_id" : ObjectId("5e3d8e7a03d395bdc21346f1"), "FavouriteTechnology" : "Spring Boot" }
{ "_id" : ObjectId("5e3d8e8f03d395bdc21346f2"), "FavouriteTechnology" : "MongoDB" }
{ "_id" : ObjectId("5e3d8ea603d395bdc21346f3"), "FavouriteTechnology" : "Groovy" }Following is the query to specify return format −
> db.demo207.aggregate([
... {
... "$group": {
... "_id": 0,
... "FavouriteTechnology": {
... "$addToSet": "$FavouriteTechnology"
... }
... }
... },
... {
... "$project": {
... "_id": 0,
... "FavouriteTechnology": 1
... }
... }
...]);This will produce the following output −
{ "FavouriteTechnology" : [ "MongoDB", "Groovy", "Spring Boot" ] }
Updated on: 27-Mar-2020
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