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Insert to specific index for MongoDB array?
To insert a specific index for MongoDB array, you can use $push operator. Let us create a collection with documents
>db.insertToSpecificIndexDemo.insertOne({"StudentName":"Larry","StudentSubjects":["MySQL","Java"]}); { "acknowledged" : true, "insertedId" : ObjectId("5c9d2562a629b87623db1b2c") } >db.insertToSpecificIndexDemo.insertOne({"StudentName":"Chris","StudentSubjects":["C++","C"]}); { "acknowledged" : true, "insertedId" : ObjectId("5c9d2573a629b87623db1b2d") }
Following is the query to display all documents from a collection with the help of find() method
> db.insertToSpecificIndexDemo.find().pretty();
This will produce the following output
{ "_id" : ObjectId("5c9d2562a629b87623db1b2c"), "StudentName" : "Larry", "StudentSubjects" : [ "MySQL", "Java" ] } { "_id" : ObjectId("5c9d2573a629b87623db1b2d"), "StudentName" : "Chris", "StudentSubjects" : [ "C++", "C" ] }
Following is the query to insert to a specific index for MongoDB array in _id “5c9d2573a629b87623db1b2d”
> db.insertToSpecificIndexDemo.update( ... { _id: ObjectId("5c9d2573a629b87623db1b2d")}, ... { $push: { ... StudentSubjects: { ... $each: [ {"CoreSubject": "MongoDB"} ], ... $position: 0 ... } ... }} ... ); WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
Let us check the value is inserted into the specific position or not. Above, we have given index 0 that would mean insertion in the beginning
> db.insertToSpecificIndexDemo.find().pretty();
This will produce the following output
{ "_id" : ObjectId("5c9d2562a629b87623db1b2c"), "StudentName" : "Larry", "StudentSubjects" : [ "MySQL", "Java" ] } { "_id" : ObjectId("5c9d2573a629b87623db1b2d"), "StudentName" : "Chris", "StudentSubjects" : [ { "CoreSubject" : "MongoDB" }, "C++", "C" ] }
Look at the sample output, the “CoreSubject”:”MongoDB” is inserted at the beginning in the MongoDB array.
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