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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" ] }
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