Weird Behiviour of findOne

distalx · November 7, 2015, 6:05am

Hi guys,

Let’s assume I have a collection called Books
{ title : “string”,
author : “string”}

Let’s take a look on following code


Template.bookList.helpers({
    books: function() {
      console.log('meteor');
      return Posts.find();
    }
  });

In this case the 'meteor' will be printed one time. But if i use findOne like this


Template.bookItem.helpers({
    book: function() {
      console.log('meteor');
      return Posts.findOne({'title':'title of the book'});
    }
  });

The 'meteor' will be printed several times(in some case two in some six).

Why’s that !?

arunoda · November 7, 2015, 6:34am

In the first case, you returned a cursor. Then blaze know how to render it in efficient manner.

In the second case you return a JS object to blaze. And that helper is re-run for every change in that document. (That’s does by findOne)

That’s the difference.