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Modify sequence in MongoDB
To modify a sequence, use findAndModify(). Let us create a collection with documents −
> db.demo261.insertOne({_id:100,Name:"Chris"}); { "acknowledged" : true, "insertedId" : 100 }
Display all documents from a collection with the help of find() method −
> db.demo261.find();
This will produce the following output −
{ "_id" : 100, "Name" : "Chris" }
Following is the query to modify sequence −
> db.demo262.insert({_id:"newId",sequence_value:0}) WriteResult({ "nInserted" : 1 }) > function getNext(sName){ ... ... var d= db.demo262.findAndModify({ ... query:{_id: sName}, ... update: {$inc:{sequence_value:1}}, ... new:true ... }); ... return d.sequence_value; ...}
Following is the query to call the above function to generate the sequence in MongoDB −
> db.demo261.insert({ ... "_id":getNext("newId"), ... "Name":"Chris" ... }) WriteResult({ "nInserted" : 1 }) > db.demo261.insert({ "_id":getNext("newId"), "Name":"Bob" }) WriteResult({ "nInserted" : 1 })
Display all documents from a collection with the help of find() method −
> db.demo261.find();
This will produce the following output −
{ "_id" : 100, "Name" : "Chris" } { "_id" : 1, "Name" : "Chris" } { "_id" : 2, "Name" : "Bob" }
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