What is returned from Mongoose query that finds no matches?

node.js mongodb mongoose database

It depends on the query. If it is a find, then results == []. If it is a findOne, then results == null. No errors if everything else is ok.

node.js mongodb mongoose database

If conditions were valid but no matches were found:

However, if some condition was invalid (e.g. field is string but you pass an object, or you pass an invalid _id)

For all three: err is {..}, result is undefined

node.js mongodb mongoose database

If using .find(),
The handy way would be

models.<your collection name>.find({ _id: `your input` }).then(data => {    if (data.length == 0) return // throw your error to the console;});