With knockout.js debug version, ko.isComputed and ko.isWriteableObservable doesn't work on create callbacks

[lisandropuzzolo]

Since withProxyDependentObservable replaces ko.dependentObservable, ko.isComputed and ko.isWriteableObservable doesn't work on create callbacks when using ko.js (DEBUG VERSION).

On theese fiddles, I test on a create ko.isComputable. On compiled ko.js version, ir alerts YES, and on debug version it alerts NO:

Here is a fiddle with debug version: http://jsfiddle.net/rZLh7/5/

An here is a fiddle with compiled version: http://jsfiddle.net/dmY8P/

¿Does anybody knows why it works this way? I use the knockoutjs debug version to develop so I can track errors easily on my code.

[sagacity]

I'm not sure why you are creating a computed within a create callback like that, but regardless, a computed will only get evaluated and initialized after mapping is complete. This is to prevent circular references.

I have updated your fiddle to illustrate how you'd use it within a create callback: http://jsfiddle.net/rZLh7/6/

[lisandropuzzolo]

Hi Roy. The fiddle I posted was just an example. I use to call constructors on create callbacks, and sometimes I need to use ko.isComputed on those constructors.

[fastfasterfastest]

I am also running into a problem with ko.isWriteableObservable not returning true for ko.computed observables during mapping.

I also see this issue was reported as https://github.com/SteveSanderson/knockout/issues/580.

Unfortunately, I cannot get jsfiddle.net to work with the mapping plugin, but here is an example. The expected behavior is that the alert should state "John Smith - name can be changed", however instead it states "John Smith - name cannot be changed". Like lisandropuzzolo I am calling a constructor during the mapping to create the view model and within that constructor ko.isWriteableObservable does not function as expected.

 function PersonViewModel(options) {
    this.name = ko.isObservable(options.name) ? options.name : ko.observable(options.name);
    this.canEditName = ko.isWriteableObservable(this.name);
}

var personMapping = {
    create: function (options) {
        var person = options.data,
            name = ko.computed({
                read: function () { return person.firstName + ' ' + person.lastName; },
                write: function (value) { /* NYI */ },
            });

        return new PersonViewModel({ name: name });
    }
};

var person = ko.mapping.fromJS({
    firstName: 'John',
    lastName: 'Smith'
}, personMapping);

alert(person.name() + " - name " + (person.canEditName ? "can" : "cannot") + " be changed");

[BrandonLWhite]

Ditto here. ko.isComputed is incorrectly returning false for me, even after the call to ko.mapping.fromJS returns. The issue for me seems to not be restricted to just within create callbacks. I will see about posting a distilled fiddle.

For the moment, now, I am kludging a workaround that looks like "if(someObservable.isActive)"