data-class function is called multiple times in KO 3.0

[lisovin]

This is best can be demonstrated by following jsbin-s - same exact code results in different behavior in KO 2.3 and 3.0:

KO 2.3: http://jsbin.com/ULovitA/3 (number of calls is 1) KO 3.0: http://jsbin.com/ULovitA/2 (number of calls is 4)

I suspect the issue is related to the change in KO 3.0 that now evaluates every binding independently (and thus calling binding function multiple times). I wonder what a good workaround might be though.

[mbest]

classBindingProvider would need to be updated to use getBindingAccessors.

[rniemeyer]

yes- that has been on my list of things to look at (providing getBindingAccessors for 3.0 support).

[mbest]

I worked on a prototype for this back in August. I pulled that out again and make some tweaks to get it working optimally with Knockout 3.0. See #19.

[mbest]

In general, you'll get the most benefit from Knockout 3.0 if you pass the observables themselves to bindings instead of unwrapping them in your bindings.

Thus you should have

      counter: function () {
        return {
          text: this.counter
        };
      }

instead of

      counter: function () {
        return {
          text: this.counter()
        };
      }

[lisovin]

@rniemeyer: New version of classBindingProvider seems to have resolved the issue. Thanks a lot!

[lisovin]

@mbest: your point regarding passing observables rather than unwrapping them in the binding is well taken, thanks for the advice.