Update date inside mongoose schema every time

Question

I'm trying to update the lastMessageAt every time the [messageSchema] is updated.

It doesn't work this way. I The only date that is generated when the messageSchema is filled with it's very first object.

How do i solve this?

Thanks in advance!

const chatSchema = new mongoose.Schema({
  userName1: String,
  userName2: String,
  messages: [messageSchema],
  lastMessageAt: {
    type: Date,
    default: Date.now
  }
});

Answer 1

You could use mongooses post middleware.

chatSchema.post('save', function(next) {
  if (this.isModified('messages')) {
    this.lastMessageAt = Date.now();
  }
  next();
});

Answer 2

found out that mongoose now has built in timestamps and they are used like this:

const chatSchema = new mongoose.Schema(
  {
    userName1: String,
    userName2: String,
    messages: [messageSchema]
  },
  { timestamps: true }
);