Removing an object in a child collection in MongoDB?

To remove an object in a child collection, use $pull in MongoDB. Let us create a collection with documents −

> db.demo715.insertOne({
...    _id:1,
...    details :
...    [
...       { 'id' : '101',
...       'Information' : [
...          {
...             'studentid' : '102',
...             "Name":"Bob"
...          },
...          {
...             'studentid' : '103',
...             "Name":"Chris"
...          }
...       ]
...    }
... ]
... });
{ "acknowledged" : true, "insertedId" : 1 }

Display all documents from a collection with the help of find() method −

> db.demo715.find();

This will produce the following output −

{ "_id" : 1, "details" : [ { "id" : "101", "Information" : [ { "studentid" : "102", "Name" : "Bob" }, { "studentid" : "103", "Name" : "Chris" } ] } ] }

Following is the query to remove an object in a child collection in MongoDB −

> db.demo715.update(
...    {"details.id":'101'},
...    { $pull: { 'details.$.Information':{studentid:'102',"Name":"Bob"} } }
... );
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

Display all documents from a collection with the help of find() method −

> db.demo715.find();

This will produce the following output −

{ "_id" : 1, "details" : [ { "id" : "101", "Information" : [ { "studentid" : "103", "Name" : "Chris" } ] } ] }