var catsObjectId = new Array();
  var data = new Array();
  Recipe.find((err,doc3)=> {
    data = doc3;
    for (var i = 0; i < data.length; i++) {
      catsObjectId.push([]);
      data[i]['categories'].forEach((item, index) => {
        Recipecat.findOne({_id: item}, (err,result)=> {
          item = result.name;
          catsObjectId.push(item);
        });
      })
    }
    console.log(catsObjectId);
  });

var recipeSchema = Schema({
  categories: [{
    type: Schema.Types.ObjectId,
    ref: 'RecipeCat',
  }]
});

var recipecatSchema = new Schema({
    name: {
        type: String,
        required: true
    }
});

catsObjectId.push([]);