Publish Counts

A package to help you publish the count of a cursor, in real time.

Installation

$ meteor add tmeasday:publish-counts

API

Simply call Counts.publish within a publication, passing in a name and a cursor:

Meteor.publish('publication', function() {
  Counts.publish(this, 'name-of-counter', Posts.find());
});

On the client side, once you've subscribed to 'publication', you can call Counts.get('name-of-counter') to get the value of the counter, reactively.

The Counts.publish function returns the observer handle that's used to maintain the counter. You can call its stop method in order to stop the observer from running.

Options

Readiness

If you publish a count within a publication that also returns cursor(s), you probably want to pass {noReady: true} as a final argument to ensure that the "data" publication sets the ready state. For example, the following publication sends down 10 posts, but allows us to see how many there are in total:

Meteor.publish('posts-with-count', function() {
  Counts.publish(this, 'posts', Posts.find(), { noReady: true });
  return Posts.find({}, { limit: 10 });
});

nonReactive

If you specify {nonReactive: true} the cursor won't be observed and only the initial count will be sent on initially subscribing. This is useful in some cases where reactivity is not desired, and can improve performance.

countFromFieldLength

countFromFieldLength allows you to specify a field to calculate the sum of its length across all documents. For example if we were to store the userIds in an array on a field called likes:

{ content: 'testing', likes: ['6PNw4GQKMA8CLprZf', 'HKv4S7xQ52h6KsXQ7'] },
{ content: 'a comment', likes: ['PSmYXrxpwg276aPf5'] }

We could then publish them like:

Meteor.publish('posts-likes-count', function() {
  Counts.publish(this, 'posts-likes', Posts.find(), { countFromFieldLength: 'likes' });
});

And calling Counts.get('posts-likes') returns 3

Template helper

To easily show the counter value within your templates, you can use the getPublishedCount template helper.

Example:

<p>There are {{getPublishedCount 'posts'}} posts</p>

Notes

The package includes a test that checks the number of observer handles opened and closed (to check for memory leaks). You need to run the enable-publication-tests-0.7.0.1 branch of percolatestudio/meteor to run it however.

License

MIT. (c) Percolate Studio

publish-counts was developed as part of the Verso project.