KnockoutJS Observable object of observables

Question

I want to make observable object of observables. For example:

        var Project = function(id, name, custId) {
            this.id = ko.observable(id);
            this.name = ko.observable(name);
            this.custId = ko.observable(custId);
        }

        var viewModel = function() {

                    this.newUpProj = ko.observable(new Project(null,null,null));
            ...
            }

Something like this... I want newUpProject to be observable and it's properties to be observables. I also tried this.newUpProj = ko.mapping.fromJS(new Project());

Edit1: It crates the object but it's properties(id, name...) are not observables...

Edit2: Use in html:

<div class="modal-body">
                <p><input type="text" id="projNameTx" data-bind="value: newUpProj.name()" /></p><br>
                <p><select data-bind="options: customers, optionsCaption: 'Choose...', value: newUpProj.custId(), optionsText: 'name', optionsValue: 'id'" 
                    size="1"></select></p>

            </div>
            <div class="modal-footer">
                <button class="btn" data-bind="click: clearModal" aria-hidden="true">Close</button>
                <button class="btn btn-primary" data-bind="click: updateFlag() ? updateProject : addProject, enable: newUpProj.custId() && newUpProj.name()">Save</button>
            </div>

Correct values are loaded in the input and the select but the Save button never disables if the input is empty(for example), because the change don't go to the model.

Answer 1

Possibly just needing to execute your newUpProj in you binding?

enable: newUpProj().custId() && newUpProj().name()

Failing that, you could try making a computed observable which is set to either true or false depending on the state of custId and name

Answer 2

Managed to do it with this: http://jsfiddle.net/wF7xY/1/

var Model = function() {
    this.data = ko.observable({}); // It doesn't work
};

var Data = {
    field1: 'test1',
    field2: 'test2'
};

var model = new Model();
ko.applyBindings(model);

ko.mapping.fromJS(Data, {}, model.data);
model.data.valueHasMutated();

HTML:

<div data-bind="text: data().field1 ? data().field1() : ''"></div>

Thanks for the help.