CODEWITHSUNDEEP
javascriptnode.jsexpressmongoose
bloppit
bloppit

Reputation: 641

Why isn't select (mongoose query) working?

I'm attempting to grab a User's highscore post. To do this, I query the Post model, finding posts with their user._id as the author in the post.

This is working just fine.

However, I only want to grab the _id and the voteCount of the post. For some reason adding a select just throws up errors and says that it's an unprocessable entity

Here is the query:

  getHighscorePost(req, res, next) {
    const firebaseUID = req.params.uid;

    User.findOne({ firebaseUID })
      .select('_id')
      .then(user => {
          Post.find({ author: user._id })
            .select('_id, voteCount')
            .sort({ voteCount: -1 })
            .limit(1)
            .then(post => res.send(post[0]))
            .catch(next);
      })
      .catch(next);
  }

I've tried putting the select before/after each of the limit and sort options.

If I omit the select then the post console logs just fine like this;

{ _id: '589ddffeb4a1477fa04d632a',
  author: '589ddffeb4a1477fa04d6326',
  text: 'This is post two. It belongs to Matt too',
  createdAt: 2,
  expiresAt: 1000000000000000000,
  university: 'University of Aberdeen',
  voteCount: 3,
  uniOnly: false,
  __v: 0,
  categories: [ 'music' ],
  votes: [],
  commenters: [],
  comments: [],
  expired: false,
  commentCount: 0,
  id: '589ddffeb4a1477fa04d632a' }

With the select added, I get nothing in the body. The error comes back as:

{ error: 'Cannot read property \'length\' of undefined' }

What's happening here?

Thank you

Upvotes: 1

Views: 159

Answers (3)

csk
csk

Reputation: 179

you can use

Post.find({ author: user._id }, {voteCount: 1})

you don't need put _id = 1 as it will be in the output by default, but in case if you don't want _id in your output, you should put _id=0.

Here is the complete code:

getHighscorePost(req, res, next) {
    const firebaseUID = req.params.uid;

    User.findOne({ firebaseUID })
      .select('_id')
      .then(user => {
          Post.find({ author: user._id }, {voteCount: 1})
            .sort({ voteCount: -1 })
            .limit(1)
            .then(post => res.send(post[0]))
            .catch(next);
      })
      .catch(next);
  }

Hopefully it should work just fine but anyhow, let me know if this works.

Upvotes: 1

rsp
rsp

Reputation: 111268

The _id should be included by default. You can try:

.select('voteCount')

Upvotes: 1

Ivan Vasiljevic
Ivan Vasiljevic

Reputation: 5708

I think that you don't need semicolon in your select. So instead of this:

.select('_id, voteCount')

your select should look like this:

.select('_id voteCount')

At least I would say so based on docs.

Upvotes: 2

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