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Implement MongoDB toLowerCase() in a forEach loop to update the name of students?
Let us first create a collection with documents wherein one of the fields is StudentName −
> db.lowerCaseDemo.insertOne({"StudentName":"JOHN SMith"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cd9a86fb50a6c6dd317ad9f")
}
> db.lowerCaseDemo.insertOne({"StudentName":"CAROL TAYLor"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cd9a88fb50a6c6dd317ada0")
}
> db.lowerCaseDemo.insertOne({"StudentName":"DAVID Miller"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cd9a89fb50a6c6dd317ada1")
}Following is the query to display all documents from a collection with the help of find() method −
> db.lowerCaseDemo.find().pretty();
This will produce the following output −
{
"_id" : ObjectId("5cd9a86fb50a6c6dd317ad9f"),
"StudentName" : "JOHN SMith"
}
{
"_id" : ObjectId("5cd9a88fb50a6c6dd317ada0"),
"StudentName" : "CAROL TAYLor"
}
{
"_id" : ObjectId("5cd9a89fb50a6c6dd317ada1"),
"StudentName" : "DAVID Miller"
}Following is the query to implement toLowerCase() −
> db.lowerCaseDemo.find({StudentName: { $exists: true}}).forEach(
function(v) {
v.StudentName = v.StudentName.toLowerCase();
db.lowerCaseDemo.save(v);
}
);Let us check all the documents once again −
> db.lowerCaseDemo.find().pretty();
This will produce the following output −
{
"_id" : ObjectId("5cd9a86fb50a6c6dd317ad9f"),
"StudentName" : "john smith"
}
{
"_id" : ObjectId("5cd9a88fb50a6c6dd317ada0"),
"StudentName" : "carol taylor"
}
{
"_id" : ObjectId("5cd9a89fb50a6c6dd317ada1"),
"StudentName" : "david miller"
}
Updated on: 30-Jul-2019
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