mongoose: find most recent document

问题:

I have mongoose schema which has a day attribute which is just

Math.floor((new Date()).getTime() / (24 * 3600 * 1000))

and I want to find the data for the last day entered so say today is 16085 then I want to find the last day entered. Or another way of saying this would be. What is the document with a day attribute less then 16085 but greater then all other documents where day is also less then 16085.

or another way

What is the maximal element of the set of all documents with a day attribute less then 16085

Other then iterating over all of my documents, how could I do this?

回答1:

In the shell it would be:

db.test.find({day: {$lt: 16085}}).sort({day: -1}).limit(1)

Which finds all the docs where day is less than 16085, sorts them on day descending, and then takes the first one.

In Mongoose it would be something like:

MyModel.find({day: {$lt: 16085}}).sort({day: -1}).limit(1).exec((err, docs) => { ... });