How to wait for the result of a mongoose query?

Question

I try to filter an array according to the result of a mongoose query. The standard filter function expect the callback to return true or false. My trouble is that this informati

Answer 1

Use the filter function from the async library instead.

UPDATE

You're pretty close in your attempt, you just need to provide the result to the callback instead of returning it:

async.filter(myArray, function(elem, callback){
  MyCollection.findOne({_id : elem}, function(err, doc) {
    callback(err == null && doc != null);
  });
}, 
function(results){
  // results is myArray filtered to just the elements where findOne found a doc
  // with a matching _id.
});