Loop with asynchronous callbacks in mongoose/mongodb/node

Question

I am new to nodejs/mongo/mongoose and i am trying to do a very simple thing. I have the following schemas:

var authorSchema = mongoose.Schema({
    name: Str         


        

Answer 1

I think you'd want to use something like async to coordinate those requests; map() seems to be a good choice:

Author.find({}, function (err, authors) {
  async.map(authors, function(author, done) {
    Book.count({author: author._id}, function(err, count) {
      if (err)
        done(err);
      else
      {
        done(null, {
          id    : author._id,
          name  : author.name,
          count : count
        });
      }           
    });
  }, function(err, author_array) {
    if (err)
    {
      // handle error
    }
    else
    { 
      /*
      res.writeHead(200, { 'Content-Type': 'application/json' });
      res.write(JSON.stringify({ authors: author_array }));
      res.end();
      */
      // Shorter:
      res.json(author_array);
    }
  });
});