Proper way to convert Data type of a field in MongoDB - mongodb-query

Question

Possible Replication of How to change the type of a field?
I am currently newly learning MongoDB and I am facing problem while converting Data type of field value to another data type.
Below is an example of my document
[
{
"Name of Restaurant": "Briyani Center",
"Address": " 336 & 338, Main Road",
"Location": "XYZQWE",
"PriceFor2": "500.0",
"Dining Rating": "4.3",
"Dining Rating Count": "1500",
},
{
"Name of Restaurant": "Veggie Conner",
"Address": " New 14, Old 11/3Q, Railway Station Road",
"Location": "ABCDEF",
"PriceFor2": "1000.0",
"Dining Rating": "4.4",
}]
Like above I have 12k documents. Notice the datatype of PriceFor2 is a string. I would like to convert the data type to Integer data type.
I have referred many amazing answers given in the above link. But when I try to run the query, I get .save() is not a function error. Please advice what is the problem.
Below is the code I used
db.chennaiData.find().forEach( function(x){ x.priceFor2= new NumberInt(x.priceFor2);
db.chennaiData.save(x);
db.chennaiData.save(x);});
This is the error I am getting..
TypeError: db.chennaiData.save is not a function

Answer 1

From MongoDB's save documentation:
Starting in MongoDB 4.2, the
db.collection.save()
method is deprecated. Use db.collection.insertOne() or db.collection.replaceOne() instead.
Likely you are having a MongoDB with version 4.2+, so the save function is no longer available. Consider migrate to the usage of insertOne and replaceOne as suggested.
For your specific scenario, it is actually preferred to do with a single update as mentioned in another SO answer. It only does one db call(while your approach fetches all documents in the collection to the application level) and performs n db call to save them back.
db.collection.update({},
[
{
$set: {
PriceFor2: {
$toDouble: "$PriceFor2"
}
}
}
],
{
multi: true
})
Mongo Playground