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How to remove key fields in MongoDB?
To remove key fields in MongoFB, you can use $unset operator. Let us first create a collection with documents −
>db.removeKeyFieldsDemo.insertOne({"StudentFirstName":"John","StudentLastName":"Doe","StudentAge":23});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cc6c8289cb58ca2b005e672")
}
>db.removeKeyFieldsDemo.insertOne({"StudentFirstName":"John","StudentLastName":"Smith","StudentAge":21});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cc6c8359cb58ca2b005e673")
}Following is the query to display all documents from a collection with the help of find() method −
> db.removeKeyFieldsDemo.find().pretty();
This will produce the following output −
{
"_id" : ObjectId("5cc6c8289cb58ca2b005e672"),
"StudentFirstName" : "John",
"StudentLastName" : "Doe",
"StudentAge" : 23
}
{
"_id" : ObjectId("5cc6c8359cb58ca2b005e673"),
"StudentFirstName" : "John",
"StudentLastName" : "Smith",
"StudentAge" : 21
}Following is the query to remove key fields. Here, we are removing the StudentAge −
> db.removeKeyFieldsDemo.updateMany({},{$unset:{StudentAge:1}});
{ "acknowledged" : true, "matchedCount" : 2, "modifiedCount" : 2 }Let us display all documents from the above collection −
> db.removeKeyFieldsDemo.find().pretty();
This will produce the following output −
{
"_id" : ObjectId("5cc6c8289cb58ca2b005e672"),
"StudentFirstName" : "John",
"StudentLastName" : "Doe"
}
{
"_id" : ObjectId("5cc6c8359cb58ca2b005e673"),
"StudentFirstName" : "John",
"StudentLastName" : "Smith"
}
Updated on: 30-Jul-2019
1K+ Views
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