Resolve empty initialised value when using model.bind

[jordan-ware]

Binding a model but no value resulted in the value being initialised with a moment object instead of the expected formatted string, resulting in nothing appearing in the text box despite the date correctly bound behind the scenes. This change fixes this issue.

[ghiscoding]

I'll have to do some more tests before merging this one, the last commit I made had something similar here and it got removed. I have to see if it was causing the infinite loop or if it was just an omission. I remember that I see more problem when I use the date picker inside a modal window component, I'll have to test against it

[jordan-ware]

Oops, hit a wrong button sorry. I was going to say I've dealt with this issue before and realized I have my own wrapper code that deals with these syncing issues and exits as early as possible.

In the below example I'm syncing a date with a moment in my wrapper, slight changes can be made to handle the formatted string instead:

    dateValueChanged(newValue?: Date, oldValue?: Date) {
        //exits early because no actual change is detected
        if (newValue && oldValue && newValue.getTime() == oldValue.getTime()) {
            return;
        } else if (!newValue && !oldValue) {
            return;
        }
        //sync value logic below - only assign new value if it's different
        if (newValue) {
            if (this.value && this.value.valueOf() == newValue.getTime()) {
                return;
            }
            this.value = moment(newValue);
        } else {
            //this could probably be avoided too
            this.value = null;
        }
    }

*edit, apologies, it's in typescript

[jordan-ware]

I'll adapt this to the model/value sync if you like, cause I noticed there's still some unnecessary cycles still happening in the current implementation

[ghiscoding]

Finally tried it, it seems to be ok with the tests I've done.