在mongodb中的模式中定义的属性未在节点中显示hisOwnProperty

Question

My user schema is

    var mongoose    =   require('mongoose');
    var userSchema  = mongoose.Schema({
          firstName     : String,
          lastName      : String,
          ...
    })

    module.exports = mongoose.model('user', userSchema,'user');

My find query on user DB

User.findById(userId,function(error,user){
    if(!error){
       console.log(user) //correctly print user schema as described above with _id
       for (var key in user) {
          if (user.hasOwnProperty(key)) {
            console.log("key ", key); //not print firstName, lastName
          }
       }
    }
})

The for in loop doesn't work as excepted, it prints different properties which is not in schema

Answer 1

That's because the returned user is a mongoose model . It has some other properties build it in it's prototype.

If you want to iterate over the user properties, you need to do this:

   console.log(user)
   var objUser = user.toObject();
   for (var key in objUser) {
      if (objUser.hasOwnProperty(key)) {
        console.log("key ", key);
      }
   }

The toObject() function will turn your mongoose model into a pure Javascript object. But, if you do this, you need to remember that mongoose model functions won't work on the pure object (because it is not a mongoose model anymore). So if you still need to use them, you need to keep a reference to the original user model.