Question

If i have a mongo document id as a string how do I query for it as an _id?

Will it work correctly to do .find({_id:'stringID'}) or do I need to convert it to a bson object first?

Answer 1

Do you mean you have the 24 hex digit string of an ObjectId?

Assuming that’s what you mean, most drivers have a way to take a string and convert it to an ObjectId. In JavaScript that’s:

.find({_id:new ObjectId("4f91bfcfaa7c5687a0c686d4")})

Updated to be a bit more useful for the node-native driver (from the documentation at https://github.com/christkv/node-mongodb-native):

// Get the objectID type
var ObjectID = require('mongodb').ObjectID;

var idString = '4e4e1638c85e808431000003';
collection.findOne({_id: new ObjectID(idString)}, console.log)  // ok
collection.findOne({_id: idString}, console.log)  // wrong! callback gets undefined