Getting a list of unique embedded/nested objects in a MongoDB document

Question

Consider the following MongoDB \"recipes\" collection:

{
  \"title\" : \"Macaroni and Cheese\",
  \"ingredients\" : [
    { \"name\" : \"noodles\", \"qty\" :         


        

Answer 1

A funny way of doing it in the mongoshell using foreach operator

var list = [];
db.recepies.find(
  {},
  {'ingredients.name' : 1, _id : 0}
).forEach(function(doc){
  var ingredients = doc.ingredients;
  for (var i=0; i< ingredients.length; i++){
    var ingredient = ingredients[i].name;
    if (list.indexOf(ingredient) == -1){
       list.push(ingredient)
    }
  }
});

after this list will contain all the elements. P.S. I am sure this is also possible with aggregation framework.