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Reverse array field in MongoDB?
To reverse array field in MongoDB, you can use forEach(). Let us first create a collection with documents −
> db.reverseArrayDemo.insertOne({"Skills":["C","Java"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ccddf99dceb9a92e6aa1946")
}Following is the query to display all documents from a collection with the help of find() method −
> db.reverseArrayDemo.find().pretty();
This will produce the following output −
{
"_id" : ObjectId("5ccddf99dceb9a92e6aa1946"),
"Skills" : [
"C",
"Java"
]
}Here is the query to reverse array field in MongoDB −
> db.reverseArrayDemo.find().forEach(function (myDocument) {
... var arrayValue = [ myDocument.Skills[1], myDocument.Skills[0] ];
... db.reverseArrayDemo.update(myDocument, { $set: {Skills : arrayValue } });
... });Let us display the document from the above collection to check the array field is now reversed or not −
> db.reverseArrayDemo.find().pretty();
This will produce the following output −
{
"_id" : ObjectId("5ccddf99dceb9a92e6aa1946"),
"Skills" : [
"Java",
"C"
]
}
Updated on: 30-Jul-2019
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