问Meteor如何接收MongoDB查询结果的更新？

EN

// collection of posts that includes array of tags
var Posts = new Meteor.Collection('posts');

// DB cursor to find all posts with 'important' in the tags array.
var cursor = Posts.find({tags: 'important'});

// watch the cursor for changes
var handle = cursor.observe({
  added: function (post) { ... }, // run when post is added
  changed: function (post) { ... } // run when post is changed
  removed: function (post) { ... } // run when post is removed
});

Posts.update(my_post_id, {$addToSet: {tags: 'important'}});