What you are thinking of sounds a lot like triggers. MongoDB does not have any support for triggers, however some people have “rolled their own” using some tricks. The key here is the oplog. When you run MongoDB in a Replica Set, all of the MongoDB actions are logged to an operations log (known as … Read more
Try the following query: collection.update( { _id: id }, { $pull: { ‘contact.phone’: { number: ‘+1786543589455’ } } } ); It will find document with the given _id and remove the phone +1786543589455 from its contact.phone array. You can use $unset to unset the value in the array (set it to null), but not to … Read more
Probably something like this where ID is your ObjectId. The first {} are necessary to identify your document. It is not required to use an ObjectId as long as you have another unique identifier in your collection. db.collection.update( { “_id”: ID, “playlists._id”: “58”}, { “$push”: {“playlists.$.musics”: { “name”: “test name”, “duration”: “4.00” } } } … Read more
You could use a regex. In your example that would be: db.stuff.find( { foo: /^bar$/i } ); I must say, though, maybe you could just downcase (or upcase) the value on the way in rather than incurring the extra cost every time you find it. Obviously this wont work for people’s names and such, but … Read more
You can create a mongoUtil.js module that has functions to both connect to mongo and return a mongo db instance: const MongoClient = require( ‘mongodb’ ).MongoClient; const url = “mongodb://localhost:27017”; var _db; module.exports = { connectToServer: function( callback ) { MongoClient.connect( url, { useNewUrlParser: true }, function( err, client ) { _db = client.db(‘test_db’); return … Read more
MongoDB 3.2 now allows one to combine data from multiple collections into one through the $lookup aggregation stage. As a practical example, lets say that you have data about books split into two different collections. First collection, called books, having the following data: { “isbn”: “978-3-16-148410-0”, “title”: “Some cool book”, “author”: “John Doe” } { … Read more
The error message is saying that there’s already a record with null as the email. In other words, you already have a user without an email address. The relevant documentation for this: If a document does not have a value for the indexed field in a unique index, the index will store a null value … Read more
As favouriteFoods is a simple array of strings, you can just query that field directly: PersonModel.find({ favouriteFoods: “sushi” }, …); // favouriteFoods contains “sushi” But I’d also recommend making the string array explicit in your schema: person = { name : String, favouriteFoods : [String] } The relevant documentation can be found here: https://docs.mongodb.com/manual/tutorial/query-arrays/
What is the default sort order when none is specified? The default internal sort order (or natural order) is an undefined implementation detail. Maintaining order is extra overhead for storage engines and MongoDB’s API does not mandate predictability outside of an explicit sort() or the special case of fixed-sized capped collections which have associated usage … Read more
db.messages.find( { headers : { From: “[email protected]” } } ) This queries for documents where headers equals { From: … }, i.e. contains no other fields. db.messages.find( { ‘headers.From’: “[email protected]” } ) This only looks at the headers.From field, not affected by other fields contained in, or missing from, headers. Dot-notation docs