how to $set a mongoDB cursor in node.js? - node.js

Question

I have a mongoDB collection which I want to add a field at random locations using $set, at least I am pretty sure its a $set. Correct me if I am wrong.
I am including code. Around the middle I include remarks of what I am trying to do:
var MongoClient = require('mongodb').MongoClient;
MongoClient.connect('mongodb://localhost:27017/weather', function(err, db) {
// Also, what is the best way to handle err in this code?
//if(err) throw err;
var query = { };
var sortorder = {"State":1, "Temperature":-1}
var xx = null;
//var cursor = db.collection('data').find();
var cursor = db.collection('data').find().sort(sortorder);
cursor.each(function(err, doc) {
//if(err) throw err;
if(doc == null) {
return db.close();
}
if (xx == doc.State){
}else{
console.dir("New state -----------" + doc.State);
console.dir("Tempurature -----------" + doc.Temperature);
// !!!!!!!!!!!!!!!!!!!!!!!!!! this is the problem area.
//--- this is the part I am trying to figure out...
update_routine = $set:{"month_high---test001":true};
doc.update = update_routine;
// How do I do a $set operation on a mongoDB cursor. which I have here.
xx = doc.State;
// add the field
//doc.update();
}
if(doc == null) {
return db.close();
}
//app.error(function(err, req, res, next){
// console.error(err);
// res.send('Fail Whale, yo.');
//});
//console.dir(doc.State + " is a state!");
});
});
~~

Answer 1

your code looks a little chaotic, but here is what you can do.
also take a look at mongodb documentation for $set: http://docs.mongodb.org/manual/reference/operator/update/set/
var cursor = db.collection('data').find().sort(sortorder);
cursor.each(function(err, doc) {
if(err) throw err;
if(doc == null) {
return db.close();
}
// until here you code makes sense, you have a cursor,
// you checked for errors and have the current document
// now you want to update a record, you can do it like this:
var myquery = {};
myquery['_id'] = doc['_id'];
// you were missing the surrounding {}
var myupdate = { $set: { field1: "whatever value", field2: 500 } };
// obviously you want to replace field1 and field2 with your actual field names
// instead of creating a new update object and using $set
// you could also just modify the 'doc' variable and pass it again
// in the update function below instead of myupdate
db.collection('data').update(myquery, myupdate, function (err, updatedDoc) {
if (err) throw err;
console.log("successfully updated document", updatedDoc);
});
});