limited

Compose $aggregate MongoDB queries for Mongoose as if $push had a $limit operator.

Fetching the "top N commits on each repository with one of these ids" is a hard task due to MongoDB's limitations on $aggregate, specifically the inability to $limit on a $push operator. limited makes this easier for you.

Install

npm install limited --save

limited(options, done)

Configuration options are detailed below.

Property | Description | Example ---------|----------------------------------------------------------------------------|---------- model | The mongoose model or raw mongodb collection you want to operate on | Commit field | The field you want to group by | 'repo' query | Optional filter so that the aggregate doesn't run on the entire collection | { repo: { $in: repoIds } } sort | Optional sort expression as an object | { created: -1 } limit | Number of documents do you want to retrieve from each match | 5

A single (albeit complex) query will be issued against the database and you'll get back a list of model documents that match your query requirements, grouped by at most limit documents per field, and sorted by sort.

var _ = require('lodash');
var limited = require('limited');
var models = require('./models');

function getLastCommitInRepositories (ids, done) {
  var options = {
    model: models.Commit,
    field: 'repo',
    query: { repo : { $in: ids } },
    limit: 5,
    sort: { created: -1 }
  };
  limited(options, find);

  function find (err, result) {
    if (err) {
      done(err); return;
    }

    models.Commit
      .find({ _id: { $in: _.flatten(result, 'documents') } })
      .lean()
      .exec(done);
  }
}

The second query isn't executed on your behalf. It's up to you to decide how you want to deal with the document ids you get back from limited.

License

MIT