Adding elements to a json while making queries to the database

Question

Adding elements to a json while making queries to the database

I am having trouble with manipulating a json while making queries on the database. I have a table Genre with the following attributes : id, name, parent_id. I want to get every genre that has an id=null and for each of them, add the attribute children with the genres that have a parent_id equal to their id.

Here is what I have done so far:

getGenres: function (req, res) {
  Genres.find().where({parent_id : null}).exec(function(err, elements) {
    if (err)
      console.log(err);
    else {
      async.each(elements, function(item, callback) {
        Genres.find().where({parent_id: item.id}).exec(function(err, items) {
          console.log(items);
          item['children'] = items; //Doesn't work but that's the idea
          callback();
        })
      })
    res.send(elements);
    }
})

} I am getting the items I want, I just don't know how to add them to the json.

json
node.js
asynchronous

Answer 1

Did you tried this instead ?

    item.children = items;

Answer 2

Ok, I found my mistake, this works correctly :

getGenres: function (req, res) {
  Genres.find().where({parent_id : null}).exec(function(err, elements) {
    if (err)
      res.send(err);
    else {
      async.each(elements, function(item, callback) {
        Genres.find().where({parent_id: item.id}).exec(function(err, items) {
          item.children = items; 
          callback();
        })
      }, function(err) {
        if (err)
          res.send(err);

        res.send(elements);
      });
    }
  })
}