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MongoDB pull with positional operator?
Use $pull operator along with positional operator($) in MongoDB. Let us first create a collection with documents −
> db.pullWithPositionalOperatorDemo.insertOne( ... { ... _id: 100, ... "StudentDetails": [ ... { ... "StudentId": "STU-1", ... "StudentFavouriteSubject": ["MongoDB", "Java"] ... }, ... { ... "StudentId": "STU-2", ... "StudentFavouriteSubject": ["PHP", "MySQL"] ... } ... ] ... } ... ); { "acknowledged" : true, "insertedId" : 100 }
Following is the query to display all documents from a collection with the help of find() method −
> db.pullWithPositionalOperatorDemo.find().pretty();
This will produce the following output −
{ "_id" : 100, "StudentDetails" : [ { "StudentId" : "STU-1", "StudentFavouriteSubject" : [ "MongoDB", "Java" ] }, { "StudentId" : "STU-2", "StudentFavouriteSubject" : [ "PHP", "MySQL" ] } ] }
Following is the query to perform pull with positional operator −
> db.pullWithPositionalOperatorDemo.update({ ... "StudentDetails" : { ... "$elemMatch" : { ... "StudentId" : "STU-2", ... "StudentFavouriteSubject" : "MySQL" ... } ... } ... }, { ... $pull : { ... "StudentDetails.$.StudentFavouriteSubject" : "MySQL" ... } ... }, { ... multi : true ... }); WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
Let us check all documents from the above collection once again −
> db.pullWithPositionalOperatorDemo.find().pretty();
This will produce the following output −
{ "_id" : 100, "StudentDetails" : [ { "StudentId" : "STU-1", "StudentFavouriteSubject" : [ "MongoDB", "Java" ] }, { "StudentId" : "STU-2", "StudentFavouriteSubject" : [ "PHP" ] } ] }
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