没有使用Array.Map（）更新Javascript对象

Question

I have an Express API in which I have the following Mongoose query that extracts posts from the database and then I want to convert the timestamp from the database (a Date() object) into a relative time string.

As you can see, I am trying to add a time property that has this string as a value to the posts object using Array.Map.

That seems to work, because logging items[0].time in the console returns the proper value (see comment in the cose).

HOWEVER! when sending the object back with res.json, the time property is not in it.

I thought this might be a client-side cache issue, but when adding another value in res.json , the new value gets sent along with the posts just fine.

Post.find({}, 'author text timestamp')
        .sort({ _id: -1 })
        .populate({ path: 'author', select: 'username' })
        .exec(function(error, posts) {
          if (error) {
            console.error(error)
          }


          items = posts.map(function(item) {
            item.time = moment(item.timestamp).fromNow()
            return item
          })

          console.log('Relative date:' + items[0].time) // This logs: "Relative date:an hour ago"

          res.json({
            posts: items
          })
          /*
            Response:

            posts: {
              0: {
                author: {_id: "5c98f40f793edf61bcc94b4d", username: "Admin"},
                text: "Why",
                timestamp: "2019-04-04T15:46:36.142Z",
                _id: "5ca626dc45734a2612acbcd2"
              }
            }
          */
        })

Is this a server-related cache issue or something unique to Mongoose objects that I don't know about?

Thanks in advance for the help.

Answer 1

我能够在我的代码中使用Post.find（）。lean（）来解决这个问题。