old_contents: var mongoose = require('mongoose');
  
  var Schema = mongoose.Schema, 
      ObjectId = Schema.ObjectId;
  
  var Question = new Schema({
      id : {type : Number, require : true, trim : true, unique : true},
      title : {type : String, required : true, trim : true},
      body : String,
      tags : Array 
  
  });
  
  module.exports = mongoose.model('Question', Question);
  
new_contents: var mongoose = require('mongoose');
  
  var Schema = mongoose.Schema, 
      ObjectId = Schema.ObjectId;
  
  var Question = new Schema({
      title : {type : String, required : true, trim : true},
      body : String,
      tags : Array 
  
  });
  
  module.exports = mongoose.model('Question', Question);
  
subject: Fix to schema to remove id. Use mongodb's built in _id.