You can use update() function to insert records in MongoDB if it does not exist. To understand the concept, let us create a collection with the document. The query to create a collection with a document is as follows −
> db.insertIfNotExistsDemo.insertOne({"StudentName":"Mike","StudentAge":21}); { "acknowledged" : true, "insertedId" : ObjectId("5c7eec7b559dd2396bcfbfc2") } > db.insertIfNotExistsDemo.insertOne({"StudentName":"Sam","StudentAge":22}); { "acknowledged" : true, "insertedId" : ObjectId("5c7eec97559dd2396bcfbfc3") }
Display all documents from a collection with the help of find() method. The query is as follows −
> db.insertIfNotExistsDemo.find().pretty(); The following is the output: { "_id" : ObjectId("5c7eec7b559dd2396bcfbfc2"), "StudentName" : "Mike", "StudentAge" : 21 } { "_id" : ObjectId("5c7eec97559dd2396bcfbfc3"), "StudentName" : "Sam", "StudentAge" : 22 }
Here is the query to insert a record if it does not already exist −
> key = {"StudentName":"David"} { "StudentName" : "David" } > value = {"StudentName":"David","StudentAge":26} { "StudentName" : "David", "StudentAge" : 26 } > db.insertIfNotExistsDemo.update(key, value, upsert=true);
The following is the output −
WriteResult({ "nMatched" : 0, "nUpserted" : 1, "nModified" : 0, "_id" : ObjectId("5c7eecd4c743760e97af8261") })
Let us check all documents from a collection. The query is as follows −
> db.insertIfNotExistsDemo.find().pretty();
The following is the output −
{ "_id" : ObjectId("5c7eec7b559dd2396bcfbfc2"), "StudentName" : "Mike", "StudentAge" : 21 } { "_id" : ObjectId("5c7eec97559dd2396bcfbfc3"), "StudentName" : "Sam", "StudentAge" : 22 } { "_id" : ObjectId("5c7eecd4c743760e97af8261"), "StudentName" : "David", "StudentAge" : 26 }
Look at the sample output, the “StudentName”:”David” and “StudentAge”:26 has been inserted successfully.