How to use MongoDB $pull to delete documents within an Array?

You need to use update command along with $pull operator to delete documents within an array. Let us create a collection with documents. Following is the query

> db.deleteDocumentsDemo.insertOne( ... { ...    "_id":100, ...    "StudentsDetails" : [ ...       { ...          "StudentId" : 1, ...          "StudentName" : "John" ...       }, ...       { ...          "StudentId" : 2, ...          "StudentName" : "Carol" ...       }, ...       { ...          "StudentId" : 3, ...          "StudentName" : "Sam" ...       }, ...       { ...          "StudentId" : 4, ...          "StudentName" : "Mike" ...       } ...    ] ... } ... ... ); { "acknowledged" : true, "insertedId" : 100 } > db.deleteDocumentsDemo.insertOne( ... { ...    "_id":200, ...    "StudentsDetails" : [ ...       { ...          "StudentId" : 5, ...          "StudentName" : "David" ...       }, ...       { ...          "StudentId" : 6, ...          "StudentName" : "Ramit" ...       }, ...       { ...          "StudentId" : 7, ...          "StudentName" : "Adam" ...       }, ...       { ...          "StudentId" : 8, ...          "StudentName" : "Larry" ...       } ...    ] ... } ... ... ); { "acknowledged" : true, "insertedId" : 200 }

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

> db.deleteDocumentsDemo.find().pretty();

This will produce the following output

{    "_id" : 100,    "StudentsDetails" : [       {          "StudentId" : 1,          "StudentName" : "John"       },       {          "StudentId" : 2,          "StudentName" : "Carol"       },       {          "StudentId" : 3,          "StudentName" : "Sam"       },       {          "StudentId" : 4,          "StudentName" : "Mike"       }    ] } {    "_id" : 200,    "StudentsDetails" : [       {          "StudentId" : 5,          "StudentName" : "David"       },       {          "StudentId" : 6,          "StudentName" : "Ramit"       },       {          "StudentId" : 7,          "StudentName" : "Adam"       },       {          "StudentId" : 8,          "StudentName" : "Larry"       }    ] }

Following is the query to delete documents within an array

> db.deleteDocumentsDemo.update({}, ... {$pull: {StudentsDetails: {StudentName: "David"}}}, ... {multi: true}); WriteResult({ "nMatched" : 2, "nUpserted" : 0, "nModified" : 1 })

Let us check the documents are deleted or not. Following is the query

> db.deleteDocumentsDemo.find().pretty();

This will produce the following output

{    "_id" : 100,    "StudentsDetails" : [       {          "StudentId" : 1,          "StudentName" : "John"       },       {          "StudentId" : 2,          "StudentName" : "Carol"       },       {          "StudentId" : 3,          "StudentName" : "Sam"       },       {          "StudentId" : 4,          "StudentName" : "Mike"       }    ] } {    "_id" : 200,    "StudentsDetails" : [       {          "StudentId" : 6,          "StudentName" : "Ramit"       },       {          "StudentId" : 7,          "StudentName" : "Adam"       },       {          "StudentId" : 8,          "StudentName" : "Larry"       }    ] }

Look at the above sample output, the “StudentId” with value 5 i.e. StudentName “David” have been deleted.