How to exclude _id without including other fields using the aggregation framework in MongoDB?


Let us first create a collection with documents −

> db.excludeIdDemo.insertOne({"StudentFirstName":"John","StudentAge":21});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5cd701a56d78f205348bc632")
}
> db.excludeIdDemo.insertOne({"StudentFirstName":"Robert","StudentAge":20});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5cd701af6d78f205348bc633")
}
> db.excludeIdDemo.insertOne({"StudentFirstName":"Chris","StudentAge":24});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5cd701b86d78f205348bc634")
}

Following is the query to display all documents from a collection with the help of find() method −

> db.excludeIdDemo.find();

This will produce the following output −

{ "_id" : ObjectId("5cd701a56d78f205348bc632"), "StudentFirstName" : "John", "StudentAge" : 21 }
{ "_id" : ObjectId("5cd701af6d78f205348bc633"), "StudentFirstName" : "Robert", "StudentAge" : 20 }
{ "_id" : ObjectId("5cd701b86d78f205348bc634"), "StudentFirstName" : "Chris", "StudentAge" : 24 }

Following is the query to exclude _id without including other fields using the aggregation framework −

> db.excludeIdDemo.aggregate(
   {
      $project :
      {
         _id : 0,
         "StudentFirstName": 1
      }
   }
);

This will produce the following output −

{ "StudentFirstName" : "John" }
{ "StudentFirstName" : "Robert" }
{ "StudentFirstName" : "Chris" }
raja
Published on 13-Jun-2019 11:58:31
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